WO2023017540A1 - Methods for refolding a solubilized recombinant protein and implementation thereof - Google Patents

Methods for refolding a solubilized recombinant protein and implementation thereof Download PDF

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WO2023017540A1
WO2023017540A1 PCT/IN2022/050721 IN2022050721W WO2023017540A1 WO 2023017540 A1 WO2023017540 A1 WO 2023017540A1 IN 2022050721 W IN2022050721 W IN 2022050721W WO 2023017540 A1 WO2023017540 A1 WO 2023017540A1
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range
recombinant
recombinant protein
solubilized
refolding
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French (fr)
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Deepak KJ
Ashwathi V
Vysakh K VISWANATH
Sabyasachi PRADHAN
Anirudha Lakshminarasimhan
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Tata Institute For Genetics And Society
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K1/00—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length
    • C07K1/107—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length by chemical modification of precursor peptides
    • C07K1/113—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length by chemical modification of precursor peptides without change of the primary structure
    • C07K1/1136—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length by chemical modification of precursor peptides without change of the primary structure by reversible modification of the secondary, tertiary or quarternary structure, e.g. using denaturating or stabilising agents
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
    • C07K16/20—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans from protozoa
    • C07K16/205—Plasmodium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/10—Immunoglobulins specific features characterized by their source of isolation or production
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/60—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments
    • C07K2317/62—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments comprising only variable region components
    • C07K2317/622—Single chain antibody (scFv)

Definitions

  • the invention generally relates to the field of recombinant protein production.
  • the present disclosure relates to the method for producing refolded functionally active recombinant proteins.
  • scFv or single chain antibody is one of the widely used antibody fragments. From the amino acid sequence of antibody, the corresponding single chain antibody containing the variable region of light (VL) and heavy chains (VH) connected by a linker can be designed, recombinantly expressed and purified for various downstream applications. They offer various advantages over the parental mAbs such as low molecular weight, ease of heterologous production, higher tissue distribution, and ability to form multimeric forms imparting multi-valency, which in turn can be engineered based on their design (Satheesh kumar, P., 2020. Expression of Single Chain Variable Fragment (scFv) Molecules in Plants: A Comprehensive Update. Molecular Biotechnology, 62(3), pp.151-167).
  • a method of refolding a solubilized recombinant protein comprising: (i) obtaining a recombinant system comprising a recombinant construct for expressing a recombinant protein; (ii) growing the recombinant system in a suitable medium to produce recombinant proteins as inclusion bodies; (iii) adding a solubilization buffer to inclusion bodies to obtain a solubilized recombinant protein from the inclusion bodies; (iv) adding a refolding buffer to the solubilized recombinant protein to obtain a mixture, wherein said refolding buffer comprises Tris in the range of 20 to 100 mM, NaCl in the range of 5 to 15 mM, KC1 in the range of 0.2 to 0.8 mM, MgChin the range of 0.5 to 4 mM, CaCh in the range of 0.5 to 4 mM, arginine
  • Figure 1 depicts schematic diagram showing the process of dilution refolding and purification of scFvs, in accordance with an embodiment of the present disclosure.
  • Figure 2A depicts Coomassie stained SDS-PAGE gel containing refolded m4B7, an anti-Pfs25 single chain antibody, after the buffer exchange column step of purification, in accordance with an embodiment of the present disclosure.
  • Figure 2B depicts Coomassie stained SDS-PAGE gel containing refolded ml269, an anti-Pfs25 single chain antibody, after the buffer exchange column step of purification., in accordance with an embodiment of the present disclosure.
  • Figure 3A depicts differential scanning fluorimetry results of refolded m4B7 protein, in accordance with an embodiment of the present disclosure.
  • Figure 3B depicts differential scanning fluorimetry results of refolded ml269 proteins, in accordance with an embodiment of the present disclosure.
  • Figure 4 displays the immunofluorescence images of immobilized in vitro culture of Plasmodium falciparum stained with refolded m4B7 and ml269 and counterstained with Alexa fluor 488 tagged anti-His antibody (Green);, in accordance with an embodiment of the present disclosure.
  • SEQ ID NO: 1 depicts amino acid sequence for m4B7
  • SEQ ID NO: 2 depicts amino acid sequence for VH of m4B7 MVKLVESGGGLVQPGGSRKLSCAASGFTFSDYGMAWFRQAPGKGPEWVA FINNLAYSIYYADTVTGRFTISRENAKNTLYLEMSSLTSEDTAMYYCARGN LYYGLDYWGQGTTVTVS
  • SEQ ID NO: 3 depicts amino acid sequence for VL of m4B7
  • SEQ ID NO: 4 depicts amino acid sequence of linker 1
  • SEQ ID NO: 5 depicts amino acid sequence of linker 2 GGGG
  • SEQ ID NO: 6 depicts amino acid sequence of linker 3
  • SEQ ID NO: 7 depicts amino acid sequence for ml269
  • SEQ ID NO: 8 depicts amino acid sequence for VH of ml269: MEVQLVESGGGLVQSGGSLRLSCAASGFTFSRNAMNWVRQAPGKGLEWV STISGSGDSTYYADSVKGRFTISRDNSKNTLYLQVNSLRAEDTAVYYCAKG DYYFDSGSYSFGMDVWGQGTTVTVSSAS
  • SEQ ID NO: 9 depicts amino acid sequence for VL of ml269:
  • recombinant protein is used to mean a protein expressed in heterologous expression system, in this case with a purification tag with minor modifications at the terminus to produce large quantities of proteins, which could potentially be used to manufacture useful commercial products.
  • inclusion bodies are often made of denatured aggregates of inactive proteins, wherein, solubilization of inclusion bodies is followed by renaturation in a suitable refolding buffer leading to the production of active proteins.
  • refolding of proteins is used to mean that solubilized/unfolded protein needs to be refolded into the correct conformation to obtain a biologically active form of the protein.
  • antibody is used to mean an immunoglobulin (Ig), which is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses.
  • Ig immunoglobulin
  • antibody fragment is used to mean the proteins that contain part of the antigen recognition site in an antibody.
  • single chain antibodies or scFv means a protein in which the variable regions of the heavy (VH) and light chains (VL) of immunoglobulins are connected with a short linker peptide of 5 to about 15 amino acids.
  • Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
  • scFv or single chain antibody is one of the widely used antibody fragment. From the amino acid sequence of the monoclonal antibody, the corresponding single chain antibody containing the variable region of light (VL) and heavy chain (VH) connected with a linker was designed, recombinantly expressed and purified for various downstream applications. Even though scFvs corresponding to the monoclonal antibodies targeted against Plasmodium antigens, Pfs25, PfCHTl and PfCSP has been found to be efficacious when expressed inside mosquitoes, there are no reports of refolding of anti-Plasmodium scFvs in the literature.
  • the present disclosure describes a method to refold single chain antibodies which are (a) derived from mouse antibodies, and (b) exhibit a theoretical pl of ⁇ 7.0.
  • anti-Pfs25 scFv designed from mouse monoclonal antibody with a theoretic pl of 6.29 was refolded.
  • the solubilized single chain antibodies m4B7 were refolded using a rapid dilution method followed by a two-step dialysis and affinity purification.
  • the quality of the refolded single chain antibodies was determined by differential scanning fluorimetry, antigen binding assay and immunofluorescence assay.
  • Single chain antibody the basic functional unit of antibody can be expressed using recombinant systems and purified in milligram quantities for downstream applications.
  • Expression of scFvs in bacteria is especially useful for engineering of antibodies, for quick screening of mutants, which would otherwise be time consuming in higher expression systems.
  • a method of refolding a solubilized recombinant protein comprising the steps of: (i) obtaining a recombinant system comprising a recombinant construct for expressing a recombinant protein; (ii) growing the recombinant system in a suitable medium to produce recombinant proteins as inclusion bodies; (iii) adding the solubilizing buffer to the inclusion bodies to obtain a solubilized recombinant protein from the inclusion bodies of step (i); (iv) adding a refolding buffer to the solubilized recombinant protein to obtain a mixture, wherein said refolding buffer comprising Tris in the range of 20 to 100 mM, NaCl in the range of 5 to 15 mM, KC1 in the range of 0.2 to 0.8 mM, MgCh in the range of 0.5 to 4 mM, CaCh in the range of 0.5 to 4 m
  • a method of refolding a solubilized recombinant protein as described herein wherein said solubilizing buffer comprises Tris-HCl having pH 8.0, 150 mM NaCl containing 6M guanidine HC1 (Gnd-HCl).
  • a method of refolding a solubilized recombinant protein as described herein wherein said refolding buffer comprises Tris-HCl in the range of 20-80 mM , NaCl in the range of 7-10 mM , KC1 in the range of 0.1-lmM, MgCh in the range of 1-3 mM, CaCh in the rage of 1-4 mM , arginine in the range of 0.2-1 M, polyethylene glycol 3350 in the range of 0.01-0.08%, GSH in the range of 0.5-1 mM, and GSSH in the range of 0.05-0.2 mM.
  • dialyzing buffer comprises Tris in the range of 20-80 mM, NaCl in the range of 120- 180 mM and Arginine in the range of 0.1-1 M.
  • scFv comprises recombinant variable regions of heavy (VH) and light (VL) antibody fragments.
  • a method of refolding a solubilized recombinant protein as described herein wherein the recombinant host cell comprises a recombinant construct comprising: (i) a first amino acid sequence as set forth in SEQ ID NO: 2 encoding a heavy chain fragment of an antibody; (ii) a second amino acid sequence as set forth in SEQ ID NO: 3 encoding a light chain fragment of an antibody; (iii) a linker having an amino acid sequence selected from a group consisting of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6, wherein said linker is positioned between the first amino acid sequence and the second amino acid sequence; and (iv) histidine tag at the C-terminal end.
  • the linker having an amino acid sequence is as set forth in SEQ ID NO: 4
  • the host cell is a prokaryote.
  • variable heavy chain (VH) and variable light chain (VL) of antibody were connected using short peptide linkers of around zero to 15 amino acids to form scFv.
  • the most used linkers consisted of a combination of glycine and serine (G and S, Table 1). It was observed that the addition of charged residues like Glutamate and Lysine enhances the solubility of scFv.
  • the number of linkers influenced in the physical characteristics of the scFv, which includes affinity constants, multimerization and stability.
  • scFv construct i.e., VH - GGGGS (linker)- VL- pET21a - scFv was transformed into BL21(DE3) and plated onto Luria Bertani (LB) plate containing 100 pg/ml ampicillin.
  • a single transformant (recombinant host cell) was inoculated into 50 ml of LB broth with 100 pg/ml ampicillin and incubated overnight at 37 °C and 120 rpm.
  • 1% of starter culture was inoculated in LB broth supplemented with 100 pg/ml ampicillin at 37 °C and 120 rpm.
  • the culture was induced with 1.0 mM IPTG and grown at 37 °C for 5 hours.
  • the cells were harvested at 6500g for 10 minutes and the pellet was resuspended in Tris- NaCl buffer, centrifuged and the pellet stored in 50 mM Tris pH 8.0, 150 mM NaCl containing 0.1 mg/mL lysozyme at -80 °C.
  • the cell pellet as obtained above was suspended in 50 mM Tris pH 8.0, 150 mM NaCl and supplemented with 1.0 % Triton X-100, 0.5 mM EDTA, 0.1 mM PMSF and 25 mM DTT (lysis buffer).
  • the bacterial suspension was passed through Stansted homogenizer at a pressure of 25,000 psi.
  • the cell lysate was centrifuged for 20 min at 15,000 g and 4°C. After discarding the supernatant, the inclusion body pellet was washed with Tris pH 8.0, 150 mM NaCl, 2% Triton X-100.
  • Triton X-l 14 exhibited a cloud point at 22°C, above this temperature micelles aggregated forming a new phase with very low water content. Endotoxin remained in the detergent phase. [0059] As depicted in the schematic diagram of Figure 1, the inclusion bodies are subjected to a series of steps such as solubilization, dilution refolding, dialysis and other chromatography-based purifications showing the to produce the refolded recombinant scFvs.
  • Isolated pellets were resuspended in 8 ml of PBS (137 mM NaCl, 2.7 mM KC1, 10 mM Phosphate buffer (pH 7.4), and vortexed for 1 minute to disperse the insoluble protein. Dispersed protein solutions were mixed with 1% (v/v) of Triton X-114 by vigorous vortexing for 1 minute. Samples were incubated on ice for 5 minutes, vortexed and subsequently incubated at 56°C for 1 minute to allow phase separation. After centrifugation at 16,200 g at room temperature for 7 seconds in a microfuge, the 3 phases (aqueous, oil and pellet) were recovered into separate tubes.
  • PBS 137 mM NaCl, 2.7 mM KC1, 10 mM Phosphate buffer (pH 7.4)
  • the pellet fraction was further washed with Tris pH 8.0, 150 mM NaCl.
  • the inclusion bodies were solubilized with Tris-HCl pH 8.0, 150 mM NaCl containing 6M guanidine HC1 (Gnd-HCl) over-night at 4°C.
  • solubilized inclusion bodies were centrifuged at 15,000 g for 30 minutes.
  • concentration of the solubilized scFv was determined by densitometry analysis from Coomassie stained SDS-PAGE gel.
  • the solubilized protein was diluted to a concentration of 50 pg/mL using the optimized refolding buffer - 50 mM Tris pH6.0, 9.6 mM NaCl, 0.4 mMKCl, 2.0 mM MgCh, 2.0 mM CaCl 2 , 0.5 M arginine, 0.05% polyethylene glycol 3350, 1 mM GSH and 0.1 mM GSSH and incubated for 24 hours at 4°C.
  • the refolded protein was dialyzed 2.5 -fold overnight at 4°C with 50 mM tris pH 8.0, 150 mM NaCl, 0.2 M Arginine.
  • the protein sample was dialyzed 25-fold with 50 mM Tris pH 8.0 and 150 mM NaCl at 4°C for 8 hrs.
  • the pH of dialyzed fraction was adjusted to 8.0 before incubating the fraction with Ni-NTA beads and pre-equilibrated with 50 mM tris pH 8.0, 150 mM NaCl.
  • the column was washed with 50 mM Tris pH 8.0, 1 M NaCl, 0.1 % of Triton X-114, 20 mM imidazole; 50 mM tris pH 8.0, IM NaCl, 20- mM imidazole; 50 mM tris pH 8.0, 150 mM NaCl, 20 mM imidazole.
  • the bound scFv was eluted with 50 mM Tris pH 8.0, 150 mM NaCl, 300 mM imidazole and eluted samples were loaded on a 10.0 % SDS-PAGE gel to determine purity and integrity of scFv.
  • Fractions containing scFv was buffer exchanged with endotoxin- free PBS using PD-10 column and concentration was adjusted to 0.5 to 1 mg/ml using centrifugal concentrators. The concentration of the protein was determined using BCA protein estimation assay and densitometry, aliquoted, flash frozen and stored at -80°C for further characterization.
  • ScFvs expressed in bacterial expression systems were labelled with fusion tags for the ease of purification and folding, where the tags included 6X Histidine Tag, Mannose Binding Protein (MBP) and Glutathione S-transferase (GST).
  • the tags were used to facilitate affinity purification based on the tag and resin interaction.
  • Ni-NTA was used for 6X-His tag
  • amylose resin was used for MBP tagged proteins
  • Glutathione was used for GST tag. It was observed that MBP tagged proteins showed better refolding and solubility compared to other methods.
  • only small tags like Hexahistidine and flag tags were used during the experimentation as high molecular weight tags like MBP, and GST might interfere with multimerization of polypeptide units during refolding.
  • the refolded m4B7 and ml269 were confirmed by SDS-PAGE separation. Both the anti- Pfs25 single chain antibodies, m4B7 ( Figure 2A) and ml269 ( Figure 2B) were confirmed based on their molecular weight ⁇ 25 kDa in the Coomassie stained SDS PAGE gels. Further, the identity of the refolded scFvs were confirmed with western blot using anti-His antibodies.
  • the profile of refolded protein was compared to the native state using differential scanning fluorimetry (DSF), a stringent method for quality control ( Figure 3A-B).
  • DSF differential scanning fluorimetry
  • Figure 3A-B a stringent method for quality control
  • the melting temperature was determined to measure the stability and, therefore the structural integrity of the protein.
  • Tycho NT.6 NanoTemper® Technologies GmbH
  • the protein sample was loaded onto capillaries, was heated from 35 °C to 90 °C using a 30 °C/min temperature ramp and the ratio of the fluorescence emission intensities at 350 nm and 330 nm (I330/350) was pre-plotted using the system software.
  • the refolded and purified m4B7 was used in triplicates to measure inflection temperature (Ti), determined to be 59.63 ⁇ 0.4 °C ( Figure 3A), which is comparable to a mammalian system expressed and purified scFv.
  • the refolded and purified ml269 was used in triplicates to measure inflection temperature (Ti), determined to be 55.17 ⁇ 0.48 °C ( Figure 3B), which is comparable to a mammalian system expressed and purified scFv.
  • the disclosed process for refolding of recombinant proteins from inclusion bodies is an efficient method to produce functionally active recombinant proteins, specifically antibody fragments.
  • the present disclosure discloses the process of dilution refolding using which functional refolded scFvs were produced; wherein anti-Pfs25 single chain antibodies, m4B7, variants of m4B7 and ml269 were refolded using the described method.
  • the refolded single chain antibodies contain a 5 amino acid linker between VH and VL domains and a non-cleavable hexa-histidine tag at the C-terminal end and the Yield of the protein ranged from 0.3 mg (m4B7) to > 2 mg (ml269) from 2 liter of induced bacterial culture.
  • the profile of the refolded protein is determined using differential scanning fluorimetry, a stringent method for quality control.
  • the present disclosure reveals that refolding of scFvs can be completed in a short period of time and is cost effective when expressed in bacteria. Further, for antibody engineering, mutants can be evaluated for their altered properties in a medium throughput mode.

Abstract

The present disclosure discloses a method for producing refolded and functionally active recombinant proteins. In particular, the disclosure discloses methods for refolding solubilized recombinant single chain antibody fragments. The disclosure also provides recombinant host cells comprising recombinant constructs for the production of recombinant single chain antibody fragments.

Description

METHOD FOR REFOLDING A SOLUBILIZED RECOMBINANT PROTEIN AND IMPLEMENTATION THEREOF
FIELD OF INVENTION
[001] The invention generally relates to the field of recombinant protein production. In particular, the present disclosure relates to the method for producing refolded functionally active recombinant proteins.
BACKGROUND OF INVENTION
[002] Refolding of inclusion body proteins into bioactive forms is burdensome and hence, requires several standardization steps. Briefly, the recovery of bioactive proteins from inclusion bodies involves four major steps comprising of isolation of inclusion bodies from host cells, solubilization of protein aggregates followed by refolding and purification of the solubilized proteins. Among these steps, solubilization and refolding are the most crucial steps for high recovery of bioactive proteins. Among other related recombinant proteins, monoclonal antibodies (mAb) occupy a large portion of therapeutic proteins (Yamada, T. Therapeutic monoclonal antibodies. Keio J. Med. 2011, 60, 37- -46). Nevertheless, the smaller versions of monoclonal antibodies e.g., scFvs, are also intensively developed as more effective biopharmaceuticals (Shaefer, J.V.; Lindner, P.; Pliickthun, A. Miniantibodies. In Antibody Engineering; Kontermann, R., Dilbel, S., Eds.; Springer-Verlag: Berlin/Heidelberg, Germany, 2010; pp. 85-99). However, expression of folded fragments has been found to be comparatively difficult due to the formation of nonnative structures (Humphreys, D.P.; Glover, D.J. Therapeutic antibody production technologies: Molecules, applications, expression, and purification. Curr. Opin. Drug Dev. 2001, 4, 172-185).
[003] scFv or single chain antibody is one of the widely used antibody fragments. From the amino acid sequence of antibody, the corresponding single chain antibody containing the variable region of light (VL) and heavy chains (VH) connected by a linker can be designed, recombinantly expressed and purified for various downstream applications. They offer various advantages over the parental mAbs such as low molecular weight, ease of heterologous production, higher tissue distribution, and ability to form multimeric forms imparting multi-valency, which in turn can be engineered based on their design (Satheesh kumar, P., 2020. Expression of Single Chain Variable Fragment (scFv) Molecules in Plants: A Comprehensive Update. Molecular Biotechnology, 62(3), pp.151-167).
[004] Although, different expression systems have been employed for scFv expression, bacterial expression systems can be less time consuming, cost effective and high yielding in comparison to others. However, due to the presence of intradomain disulphide bonds, the folding of scFv has been not optimal in bacteria, as evident from the reported literature (Gil, D. and Schrum, A., 2013. Strategies to stabilize compact folding and minimize aggregation of antibody -based fragments. Advances in Bioscience and Biotechnology, 04(04), pp.73-84).
[005] Although, there are several reports describing the refolding of recombinant proteins from inclusion bodies, there is an unmet need to standardize efficient methods to produce functionally active recombinant proteins, specifically antibody fragments. Further, a rapid, cost-effective method with high yield using the bacterial expression system is the need of the hour.
SUMMARY OF THE INVENTION
[006] In an aspect of the present disclosure, there is provided a method of refolding a solubilized recombinant protein, said method comprising: (i) obtaining a recombinant system comprising a recombinant construct for expressing a recombinant protein; (ii) growing the recombinant system in a suitable medium to produce recombinant proteins as inclusion bodies; (iii) adding a solubilization buffer to inclusion bodies to obtain a solubilized recombinant protein from the inclusion bodies; (iv) adding a refolding buffer to the solubilized recombinant protein to obtain a mixture, wherein said refolding buffer comprises Tris in the range of 20 to 100 mM, NaCl in the range of 5 to 15 mM, KC1 in the range of 0.2 to 0.8 mM, MgChin the range of 0.5 to 4 mM, CaCh in the range of 0.5 to 4 mM, arginine in the range of 0.5-1.0 M, polyethylene glycol 3350 in the range of 0.05 to 0.1%, GSH 1 to 2 mM and GSSH in the range of 0.1 to 0.2 mM; (v) incubating the mixture at a pH in the range of 5 to 7 and at a temperature in the range of 4 C to about 10 C, for a time period in the range of 24 to 64 hours to obtain a refolded recombinant protein; (vi) dialyzing the refolded recombinant protein at a temperature in the range of 4 °C - 10°C with a dialyzing buffer comprising of 50 mM Tris pH 8.0, 150 mM NaCl and 0.2 M Arginine and, (vi) purifying the dialyzed recombinant protein with Ni-NTA based affinity purification.
[007] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[008] The following drawings form a part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[009] Figure 1 depicts schematic diagram showing the process of dilution refolding and purification of scFvs, in accordance with an embodiment of the present disclosure.
[0010] Figure 2A depicts Coomassie stained SDS-PAGE gel containing refolded m4B7, an anti-Pfs25 single chain antibody, after the buffer exchange column step of purification, in accordance with an embodiment of the present disclosure.
[0011] Figure 2B depicts Coomassie stained SDS-PAGE gel containing refolded ml269, an anti-Pfs25 single chain antibody, after the buffer exchange column step of purification., in accordance with an embodiment of the present disclosure.
[0012] Figure 3A depicts differential scanning fluorimetry results of refolded m4B7 protein, in accordance with an embodiment of the present disclosure.
[0013] Figure 3B depicts differential scanning fluorimetry results of refolded ml269 proteins, in accordance with an embodiment of the present disclosure. [0014] Figure 4 displays the immunofluorescence images of immobilized in vitro culture of Plasmodium falciparum stained with refolded m4B7 and ml269 and counterstained with Alexa fluor 488 tagged anti-His antibody (Green);, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.
Sequences of the present disclosure:
[0016] SEQ ID NO: 1 depicts amino acid sequence for m4B7
MVKLVESGGGLVQPGGSRKLSCAASGFTFSDYGMAWFRQAPGKGPEWVA FINNLAYSIYYADTVTGRFTISRENAKNTLYLEMSSLTSEDTAMYYCARGN LYYGLDYWGQGTTVTVSSGGGGSDIEMTQSPSSMFASLGDRVSLSCRASQ DIRGNLDWFQQKPGGTIKLLIYSTSNLNSGVPSRFSGSGSGSDYSLTISSLES EDFADYYCLQRNAYPLTFGSGTKLEIKRAAALEHHHHHH
[0017] SEQ ID NO: 2 depicts amino acid sequence for VH of m4B7 MVKLVESGGGLVQPGGSRKLSCAASGFTFSDYGMAWFRQAPGKGPEWVA FINNLAYSIYYADTVTGRFTISRENAKNTLYLEMSSLTSEDTAMYYCARGN LYYGLDYWGQGTTVTVS
[0018] SEQ ID NO: 3 depicts amino acid sequence for VL of m4B7
DIEMTQSPSSMFASLGDRVSLSCRASQDIRGNLDWFQQKPGGTIKLLIYSTS NLNSGVPSRFSGSGSGSDYSLTISSLESEDFADYYCLQRNAYPLTFGSGTKL EIKRAAA
[0019] SEQ ID NO: 4 depicts amino acid sequence of linker 1
GGGGS
[0020] SEQ ID NO: 5 depicts amino acid sequence of linker 2 GGGG [0021] SEQ ID NO: 6 depicts amino acid sequence of linker 3
GGGGS GGGGS GGGGS
[0022] SEQ ID NO: 7 depicts amino acid sequence for ml269
MEVQLVESGGGLVQSGGSLRLSCAASGFTFSRNAMNWVRQAPGKGLEWV STISGSGDSTYYADSVKGRFTISRDNSKNTLYLQVNSLRAEDTAVYYCAKG DYYFDSGSYSFGMDVWGQGTTVTVSSASGGGGSEIVLTQSPGTLSLSPGER ATLSCRTSQSVSSSYLAWYQQKPGQAPRLLMYGASSRATGIPDRFSGSGSG TDFTLTISRLEPEDFAVYYCQQYGNSFGQGTRLEIKRLEHHHHHH
[0023] SEQ ID NO: 8 depicts amino acid sequence for VH of ml269: MEVQLVESGGGLVQSGGSLRLSCAASGFTFSRNAMNWVRQAPGKGLEWV STISGSGDSTYYADSVKGRFTISRDNSKNTLYLQVNSLRAEDTAVYYCAKG DYYFDSGSYSFGMDVWGQGTTVTVSSAS
[0024] SEQ ID NO: 9 depicts amino acid sequence for VL of ml269:
EIVLTQSPGTLSLSPGERATLSCRTSQSVSSSYLAWYQQKPGQAPRLLMYG ASSRATGIPDRFSGSGSGTDFTLTISRLEPEDFAVYYCQQYGNSFGQGTRLEI KR
Definitions
[0025] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.
[0026] The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
[0027] The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”.
[0028] Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps. [0029] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.
[0030] The term “recombinant protein” is used to mean a protein expressed in heterologous expression system, in this case with a purification tag with minor modifications at the terminus to produce large quantities of proteins, which could potentially be used to manufacture useful commercial products.
[0031] The term “inclusion bodies” are often made of denatured aggregates of inactive proteins, wherein, solubilization of inclusion bodies is followed by renaturation in a suitable refolding buffer leading to the production of active proteins.
[0032] The term “refolding of proteins” is used to mean that solubilized/unfolded protein needs to be refolded into the correct conformation to obtain a biologically active form of the protein.
[0033] The term “antibody” is used to mean an immunoglobulin (Ig), which is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses.
[0034] The term “antibody fragment” is used to mean the proteins that contain part of the antigen recognition site in an antibody.
[0035] The term “single chain antibodies or scFv” means a protein in which the variable regions of the heavy (VH) and light chains (VL) of immunoglobulins are connected with a short linker peptide of 5 to about 15 amino acids.
[0036] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
[0037] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0038] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.
[0039] As discussed in the background section, scFv or single chain antibody is one of the widely used antibody fragment. From the amino acid sequence of the monoclonal antibody, the corresponding single chain antibody containing the variable region of light (VL) and heavy chain (VH) connected with a linker was designed, recombinantly expressed and purified for various downstream applications. Even though scFvs corresponding to the monoclonal antibodies targeted against Plasmodium antigens, Pfs25, PfCHTl and PfCSP has been found to be efficacious when expressed inside mosquitoes, there are no reports of refolding of anti-Plasmodium scFvs in the literature.
[0040] Hence, to overcome the shortcomings of prior art, the present disclosure describes a method to refold single chain antibodies which are (a) derived from mouse antibodies, and (b) exhibit a theoretical pl of < 7.0. As a representative example, anti-Pfs25 scFv designed from mouse monoclonal antibody with a theoretic pl of 6.29 was refolded. The solubilized single chain antibodies m4B7 were refolded using a rapid dilution method followed by a two-step dialysis and affinity purification. The quality of the refolded single chain antibodies was determined by differential scanning fluorimetry, antigen binding assay and immunofluorescence assay. Single chain antibody, the basic functional unit of antibody can be expressed using recombinant systems and purified in milligram quantities for downstream applications. Expression of scFvs in bacteria is especially useful for engineering of antibodies, for quick screening of mutants, which would otherwise be time consuming in higher expression systems. [0041] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein, comprising the steps of: (i) obtaining a recombinant system comprising a recombinant construct for expressing a recombinant protein; (ii) growing the recombinant system in a suitable medium to produce recombinant proteins as inclusion bodies; (iii) adding the solubilizing buffer to the inclusion bodies to obtain a solubilized recombinant protein from the inclusion bodies of step (i); (iv) adding a refolding buffer to the solubilized recombinant protein to obtain a mixture, wherein said refolding buffer comprising Tris in the range of 20 to 100 mM, NaCl in the range of 5 to 15 mM, KC1 in the range of 0.2 to 0.8 mM, MgCh in the range of 0.5 to 4 mM, CaCh in the range of 0.5 to 4 mM, arginine in the range of 0.5-1.0 M, polyethylene glycol 3350 in the range of 0.05 to 0.1%, GSH 1 to 2 mM and GSSH in the range of 0.1 to 0.2 mM; (v) incubating the mixture at a pH in the range of 5 to 7 and at a temperature in the range of 4°C to about 10°C, for a time period in the range of 24 to 64 hours to obtain a refolded recombinant protein; (vi) dialyzing the refolded recombinant protein at a temperature in the range of 4 °C to about 10°C with a dialyzing buffer comprising 50 mM Tris pH 8.0, 150 mM NaCl and 0.2 M Arginine to obtain a dialyzed recombinant protein; and, (vi) purifying the dialyzed recombinant protein by a method selected from the group consisting of Ni-NTA based affinity purification.
[0042] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein said solubilizing buffer comprises Tris-HCl having pH 8.0, 150 mM NaCl containing 6M guanidine HC1 (Gnd-HCl).
[0043] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein said refolding buffer comprises Tris-HCl in the range of 20-80 mM , NaCl in the range of 7-10 mM , KC1 in the range of 0.1-lmM, MgCh in the range of 1-3 mM, CaCh in the rage of 1-4 mM , arginine in the range of 0.2-1 M, polyethylene glycol 3350 in the range of 0.01-0.08%, GSH in the range of 0.5-1 mM, and GSSH in the range of 0.05-0.2 mM. [0044] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein the said dialyzing buffer comprises Tris in the range of 20-80 mM, NaCl in the range of 120- 180 mM and Arginine in the range of 0.1-1 M.
[0045] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein said solubilized recombinant protein comprises recombinant antibodies or recombinant antibody fragments or scFv.
[0046] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein said scFv comprises recombinant variable regions of heavy (VH) and light (VL) antibody fragments.
[0047] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein said recombinant antibody fragment are anti-Pfs25 single chain antibody m4B7, and ml269.
[0048] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein the recombinant host cell comprises a recombinant construct comprising: (i) a first amino acid sequence as set forth in SEQ ID NO: 2 encoding a heavy chain fragment of an antibody; (ii) a second amino acid sequence as set forth in SEQ ID NO: 3 encoding a light chain fragment of an antibody; (iii) a linker having an amino acid sequence selected from a group consisting of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6, wherein said linker is positioned between the first amino acid sequence and the second amino acid sequence; and (iv) histidine tag at the C-terminal end. In an embodiment of the present disclosure, the linker having an amino acid sequence is as set forth in SEQ ID NO: 4
[0049] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein the host cell is a prokaryote. [0050] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein said prokaryote is E. coli.
[0051] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein the method leads to production of the solubilized recombinant protein in the range of 0.75-1.5 mg/ml.
[0052] In an embodiment of the present disclosure, there is provided a method of refolding a solubilized recombinant protein as described herein, wherein the solubilized recombinant protein comprises recombinant antibody fragments having a yield in the range of 0.1 mg/L to 1.5 mg/L
[0053] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible.
EXAMPLES
[0054] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices, and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply.
EXAMPLE 1
1.1. Preparation of construct using linker
[0055] The gene sequence encoding m4B7 (amino acid sequence as set forth in SEQ ID NO: 1) and ml269 (amino acid sequence as set forth in SEQ ID NO: 7) (Table 2) were synthesized using Genscript with a non-cleavable C-terminal hexa-histidine tag and subcloned into pET21a vector with Ndel and BamHI restriction sites. The construct of single chain antibody consisted of variable heavy chain and variable light chain which was connected by a five amino acid linker (GGGGS, SEQ ID NO: 4). 1.2. His tag spacer- LE
[0056] The variable heavy chain (VH) and variable light chain (VL) of antibody were connected using short peptide linkers of around zero to 15 amino acids to form scFv. The most used linkers consisted of a combination of glycine and serine (G and S, Table 1). It was observed that the addition of charged residues like Glutamate and Lysine enhances the solubility of scFv. The number of linkers influenced in the physical characteristics of the scFv, which includes affinity constants, multimerization and stability.
Table 1: Alternative linkers for preparing the constructs
Figure imgf000012_0001
Table 2: Sequences of the present disclosure
Figure imgf000012_0002
Figure imgf000013_0002
EXAMPLE 2
Transformation, inoculation. growth, and induction
Figure imgf000013_0001
[0057] scFv construct, i.e., VH - GGGGS (linker)- VL- pET21a - scFv was transformed into BL21(DE3) and plated onto Luria Bertani (LB) plate containing 100 pg/ml ampicillin. A single transformant (recombinant host cell) was inoculated into 50 ml of LB broth with 100 pg/ml ampicillin and incubated overnight at 37 °C and 120 rpm. 1% of starter culture was inoculated in LB broth supplemented with 100 pg/ml ampicillin at 37 °C and 120 rpm. At an optical density, ODeoonm of 0.9, the culture was induced with 1.0 mM IPTG and grown at 37 °C for 5 hours. The cells were harvested at 6500g for 10 minutes and the pellet was resuspended in Tris- NaCl buffer, centrifuged and the pellet stored in 50 mM Tris pH 8.0, 150 mM NaCl containing 0.1 mg/mL lysozyme at -80 °C.
EXAMPLE 3
Preparation and Solubilization of inclusion body
[0058] The cell pellet as obtained above was suspended in 50 mM Tris pH 8.0, 150 mM NaCl and supplemented with 1.0 % Triton X-100, 0.5 mM EDTA, 0.1 mM PMSF and 25 mM DTT (lysis buffer). The bacterial suspension was passed through Stansted homogenizer at a pressure of 25,000 psi. The cell lysate was centrifuged for 20 min at 15,000 g and 4°C. After discarding the supernatant, the inclusion body pellet was washed with Tris pH 8.0, 150 mM NaCl, 2% Triton X-100. Triton X-l 14 exhibited a cloud point at 22°C, above this temperature micelles aggregated forming a new phase with very low water content. Endotoxin remained in the detergent phase. [0059] As depicted in the schematic diagram of Figure 1, the inclusion bodies are subjected to a series of steps such as solubilization, dilution refolding, dialysis and other chromatography-based purifications showing the to produce the refolded recombinant scFvs.
[0060] Isolated pellets were resuspended in 8 ml of PBS (137 mM NaCl, 2.7 mM KC1, 10 mM Phosphate buffer (pH 7.4), and vortexed for 1 minute to disperse the insoluble protein. Dispersed protein solutions were mixed with 1% (v/v) of Triton X-114 by vigorous vortexing for 1 minute. Samples were incubated on ice for 5 minutes, vortexed and subsequently incubated at 56°C for 1 minute to allow phase separation. After centrifugation at 16,200 g at room temperature for 7 seconds in a microfuge, the 3 phases (aqueous, oil and pellet) were recovered into separate tubes. The pellet fraction was further washed with Tris pH 8.0, 150 mM NaCl. The inclusion bodies were solubilized with Tris-HCl pH 8.0, 150 mM NaCl containing 6M guanidine HC1 (Gnd-HCl) over-night at 4°C.
EXAMPLE 4
Dilution, refolding and dialysis of solubilized protein
[0061] The solubilized inclusion bodies were centrifuged at 15,000 g for 30 minutes. The concentration of the solubilized scFv was determined by densitometry analysis from Coomassie stained SDS-PAGE gel. The solubilized protein was diluted to a concentration of 50 pg/mL using the optimized refolding buffer - 50 mM Tris pH6.0, 9.6 mM NaCl, 0.4 mMKCl, 2.0 mM MgCh, 2.0 mM CaCl2, 0.5 M arginine, 0.05% polyethylene glycol 3350, 1 mM GSH and 0.1 mM GSSH and incubated for 24 hours at 4°C. The refolded protein was dialyzed 2.5 -fold overnight at 4°C with 50 mM tris pH 8.0, 150 mM NaCl, 0.2 M Arginine. The protein sample was dialyzed 25-fold with 50 mM Tris pH 8.0 and 150 mM NaCl at 4°C for 8 hrs.
EXAMPLE 5
Purification of scFv
[0062] Following dialysis, the pH of dialyzed fraction was adjusted to 8.0 before incubating the fraction with Ni-NTA beads and pre-equilibrated with 50 mM tris pH 8.0, 150 mM NaCl. The column was washed with 50 mM Tris pH 8.0, 1 M NaCl, 0.1 % of Triton X-114, 20 mM imidazole; 50 mM tris pH 8.0, IM NaCl, 20- mM imidazole; 50 mM tris pH 8.0, 150 mM NaCl, 20 mM imidazole. The bound scFv was eluted with 50 mM Tris pH 8.0, 150 mM NaCl, 300 mM imidazole and eluted samples were loaded on a 10.0 % SDS-PAGE gel to determine purity and integrity of scFv. Fractions containing scFv was buffer exchanged with endotoxin- free PBS using PD-10 column and concentration was adjusted to 0.5 to 1 mg/ml using centrifugal concentrators. The concentration of the protein was determined using BCA protein estimation assay and densitometry, aliquoted, flash frozen and stored at -80°C for further characterization.
[0063] ScFvs expressed in bacterial expression systems were labelled with fusion tags for the ease of purification and folding, where the tags included 6X Histidine Tag, Mannose Binding Protein (MBP) and Glutathione S-transferase (GST). The tags were used to facilitate affinity purification based on the tag and resin interaction. Ni-NTA was used for 6X-His tag, amylose resin was used for MBP tagged proteins and Glutathione was used for GST tag. It was observed that MBP tagged proteins showed better refolding and solubility compared to other methods. However, only small tags like Hexahistidine and flag tags were used during the experimentation as high molecular weight tags like MBP, and GST might interfere with multimerization of polypeptide units during refolding.
EXAMPLE 6
Profile assessment and validation of refolded protein
[0064] After the buffer exchange column step of purification, the refolded m4B7 and ml269 were confirmed by SDS-PAGE separation. Both the anti- Pfs25 single chain antibodies, m4B7 (Figure 2A) and ml269 (Figure 2B) were confirmed based on their molecular weight ~ 25 kDa in the Coomassie stained SDS PAGE gels. Further, the identity of the refolded scFvs were confirmed with western blot using anti-His antibodies.
[0065] The profile of refolded protein was compared to the native state using differential scanning fluorimetry (DSF), a stringent method for quality control (Figure 3A-B). In this method, the melting temperature was determined to measure the stability and, therefore the structural integrity of the protein. Using Tycho NT.6 (NanoTemper® Technologies GmbH), the protein sample was loaded onto capillaries, was heated from 35 °C to 90 °C using a 30 °C/min temperature ramp and the ratio of the fluorescence emission intensities at 350 nm and 330 nm (I330/350) was pre-plotted using the system software. The refolded and purified m4B7 was used in triplicates to measure inflection temperature (Ti), determined to be 59.63 ± 0.4 °C (Figure 3A), which is comparable to a mammalian system expressed and purified scFv. Similarly, the refolded and purified ml269 was used in triplicates to measure inflection temperature (Ti), determined to be 55.17 ± 0.48 °C (Figure 3B), which is comparable to a mammalian system expressed and purified scFv.
[0066] For immunofluorescence assay, blood smears containing zygotes and ookinetes were prepared on glass slides and fixed with chilled methanol. Blocking and permeabilization were carried out simultaneously by incubating with 5 % BSA and 0.2 % saponin (in IX PBS) for 60 min at 25 °C. The slides were washed and incubated with 1 pg of m4B7 (in 5 % BSA and PBS) at 4 °C for 16 hours, and subsequently probed with refolded m4B7 and ml269 and counterstained with Alexa fluor 488 conjugated anti-His antibody(green) and conjugated anti-mouse IgG secondary antibodies (as shown in Figure 4). Slides were mounted with Prolong Gold antifade with DAPI for staining DNA (Thermo Fischer Scientific, Eugene) and examined using a fluorescence microscope.
Overall, it can be inferred from the above-described examples that the disclosed process for refolding of recombinant proteins from inclusion bodies is an efficient method to produce functionally active recombinant proteins, specifically antibody fragments.
Advantages of the present disclosure
[0067] The present disclosure discloses the process of dilution refolding using which functional refolded scFvs were produced; wherein anti-Pfs25 single chain antibodies, m4B7, variants of m4B7 and ml269 were refolded using the described method. The refolded single chain antibodies contain a 5 amino acid linker between VH and VL domains and a non-cleavable hexa-histidine tag at the C-terminal end and the Yield of the protein ranged from 0.3 mg (m4B7) to > 2 mg (ml269) from 2 liter of induced bacterial culture. The profile of the refolded protein is determined using differential scanning fluorimetry, a stringent method for quality control. The present disclosure reveals that refolding of scFvs can be completed in a short period of time and is cost effective when expressed in bacteria. Further, for antibody engineering, mutants can be evaluated for their altered properties in a medium throughput mode.

Claims

I/We Claim:
1. A method of refolding a solubilized recombinant protein, comprising the steps of: i. obtaining a recombinant host cell comprising a recombinant construct for expressing a recombinant protein; ii. growing the recombinant host cell in a suitable medium to produce recombinant proteins as inclusion bodies; iii. adding a solubilizing buffer to the inclusion bodies to obtain a solubilized recombinant protein from the inclusion bodies of step (ii); iv. adding a refolding buffer to the solubilized recombinant protein to obtain a mixture , wherein said refolding buffer comprises Tris in the range of 20 to 100 mM, NaCl in the range of 5 to 15 mM, KC1 in the range of 0.2 to 0.8 mM, MgChin the range of 0.5 to 4 mM, CaCh in the range of 0.5 to 4 mM, arginine in the range of 0.5-1.0 M, polyethylene glycol 3350 in the range of 0.05 to 0.1%, GSH 1 to 2 mM and GSSH in the range of 0.1 to 0.2 mM ; v. incubating the mixture at a pH in the range of 5 to 7 and at a temperature in the range of 4°C to about 10°C, for a time period in the range of 24 to 64 hours to obtain a refolded recombinant protein; vi. dialyzing the refolded recombinant protein at a temperature in the range of 4°C-10°C with a dialyzing buffer comprising Tris in the range of 30-60 mM, NaCl in the range of 120-160 mM and Arginine in the range of 0.1 -0.3 M to obtain a dialyzed recombinant protein; and vii. purifying the dialyzed recombinant protein by Ni-NTA based affinity purification.
2. The method as claimed in claim 1 , wherein said solubilizing buffer comprises Tris-HCl having pH 8.0, 150 mM NaCl containing 6M guanidine HC1 (Gnd- HC1).
3. The method as claimed in claim 1, wherein said refolding buffer comprises Tris-HCl in the range of 20-80 mM, NaCl in the range of 7-10 mM, KC1 in the range of 0.1-lmM, MgCh in the range of 1-3 mM, CaCh in the range of 1-4 mM, arginine in the range of 0.2-1 M, polyethylene glycol 3350 in the range of 0.01-0.08%, GSH in the range of 0.5-1 mM, and GSSH in the range of 0.05-0.2 mM.
4. The method as claimed in claim 1, wherein said dialyzing buffer comprises Tris in the range of 20-80 mM, NaCl in the range of 120-180 mM and Arginine in the range of 0.1-1 M.
5. The method as claimed in claim 1, wherein said solubilized recombinant protein comprises recombinant antibodies, or recombinant antibody fragments, or ScFv.
6. The method as claimed in claim 5, wherein said ScFv comprise recombinant VH antibody fragments and recombinant VL antibody fragments.
7. The method as claimed in claim 6, wherein said recombinant antibody fragment are anti-Pfs25 single chain antibodies m4B7, and ml269.
8. The method as claimed in claim 1, wherein the recombinant host cell comprises a recombinant construct comprising: i) a first amino acid sequence as set forth in SEQ ID NO: 2 encoding a heavy chain fragment of an antibody;
(i) a second amino acid sequence as set forth in SEQ ID NO: 3 encoding a light chain fragment of an antibody;
(ii) a linker having an amino acid sequence selected from the group consisting of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6; and wherein said linker is positioned between the first amino acid sequence and the second amino acid sequence; and
(iii) histidine tag at the C-terminal end.
9. The method as claimed in claim 8, wherein the linker having an amino acid sequence as set forth in SEQ ID NO: 4.
10. The method as claimed in claim 8, wherein the host cell is a prokaryote.
11. The method as claimed in claim 10, wherein said prokaryote is E.coli.
12. The method as claimed in claim 1, wherein the method leads to production of the solubilized recombinant protein in the range of 0.75-1.5 mg/ml.
13. The method as claimed in claim 5 or 12, wherein the solubilized recombinant protein comprises recombinant antibody fragments having a yield in the range of 0.1 mg/L to 1.5 mg/L.
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Citations (2)

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Publication number Priority date Publication date Assignee Title
WO2012054679A1 (en) * 2010-10-20 2012-04-26 Medimmune, Llc Methods for processing inclusion bodies
AU2007272412B2 (en) * 2006-07-14 2013-11-07 Genentech, Inc. Refolding of recombinant proteins

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2007272412B2 (en) * 2006-07-14 2013-11-07 Genentech, Inc. Refolding of recombinant proteins
WO2012054679A1 (en) * 2010-10-20 2012-04-26 Medimmune, Llc Methods for processing inclusion bodies

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