KR102295015B1 - Silk fibroin aqueous solution with extreme stability in aqueous phase - Google Patents

Abstract

The present invention relates to an aqueous solution of a silk fibroin protein with long-term stability in a water-soluble state, and specifically, to an aqueous solution of a silk fibroin protein, which contains a light chain of the fibroin protein to be applied to products at high concentrations while having long-term stability.

Description

Silk fibroin aqueous solution with extreme stability in aqueous phase}

The present invention relates to an aqueous solution of silk fibroin having extreme stability in aqueous phase, maintaining the physiological activity of silk fibroin protein, and can be applied at high concentrations to cosmetics, health functional foods, and foods.

Silk fibers and proteins secreted from domesticated silkworms (Bombyx mori) have been used in the textile industry for centuries. Secreted proteins have recently been used as biomaterials for biomedical applications including structural components and protein solutions. Naturally, silkworm protein exists as a mixture of silk proteins fibroin and sericin, which acts as an adhesive that binds fibroin and maintains the shape of the cocoon.

Removal of sericin by extraction with detergent or high-temperature, high-alkali washing results in sericin-free fibroin fibers comprising heavy and light chain fibroin proteins joined through a single disulfide linkage. Conversion of these fibrils into water-soluble silk fibroin proteins requires the addition of concentrated salts (e.g., 8-10 M lithium bromide), which inhibit intermolecular and intramolecular ionic and hydrogen bonds that render fibroin proteins insoluble in water. .

Silk fibroin protein applications require removal of high concentrations of LiBr salts, typically through the use of dialysis, so that the salts do not interfere with the proper functioning of the material in a given environment.

Without these salts competing for ionic and hydrogen bonding of dissolved silk fibroin, silk fibroin protein solutions are relatively unstable, susceptible to protein aggregation, and often precipitate from aqueous solutions within days.

Aggregation is believed to occur through interactions between fibroin proteins followed by gelation of the material by the formation of a beta-fold secondary protein structure between hydrophobic amino acid motifs of the fibroin heavy chain.

Once these structures are formed, the conversion of the soluble fibroin solution to the insoluble fibroin gel is rapid and largely irreversible, limiting the application of the solution to aqueous based applications due to the limited shelf life of the material.

In order to combat the tendency of fibroin in aqueous solution to gel, attempts have been made to minimize protein aggregation and subsequent formation of beta-folds. Lowering the fibroin concentration in solution is a holistic approach aimed at attenuating the protein-protein interactions that precede the formation of these structures, but may result in fibroin solutions that are too dilute for proper protein applications.

Alternatively, adjustment of the aqueous solution that interferes with protein aggregation and/or beta-fold formation (eg, solution pH, addition of stabilizing additives) can prevent these from happening. However, these controls and the addition of chemicals can increase biological toxicity or limit the application of the next step by introducing incompatible agents in solution.

Registered Patent Publication No. 10-1881586 (published on July 24, 2018)

An object of the present invention is to improve the performance of silk fibroin that aggregates in an aqueous solution to provide an aqueous solution of silk fibroin having extreme stability in an aqueous phase that is maintained without agglomeration or destabilization even in an aqueous solution for a long period of time.

In order to solve the above problems, the present invention is to provide an aqueous solution of fibroin protein, characterized in that it includes a light chain of the fibroin protein in the aqueous solution of fibroin protein having stability in aqueous solution. .

In addition, the fibroin protein has a heavy chain (Heavy Chain) and a light chain (Light Chain) to provide an aqueous solution of the fibroin protein characterized in that it exists in a combined state as a means of solving the problem.

In addition, it is intended as a means of solving the problem to provide an aqueous solution of fibroin protein, characterized in that a plurality of light chains are coated on the outer peripheral surface of the heavy chain.

In addition, the light chain (Light Chain) is to provide an aqueous solution of fibroin protein characterized in that it exists in a state bound to the hydrophobic part (Hydrophobic part) of the heavy chain (Heavy Chain) as a means of solving the problem.

In addition, it is intended as a means of solving the problem to provide an anti-inflammatory therapeutic agent comprising an aqueous solution of fibroin protein.

In addition, it is intended as a means of solving the problem to provide a therapeutic agent for skin regeneration comprising an aqueous solution of fibroin protein.

In addition, it is intended as a means to solve the problem to provide a cosmetic raw material for skin regeneration consisting of an aqueous solution of fibroin protein.

In addition, it is intended as a means to solve the problem to provide a food or drink composed of an aqueous fibroin protein solution.

The present invention can provide an aqueous solution of silk fibroin having extreme stability in an aqueous phase that is maintained without aggregation or destabilization even in an aqueous solution for a long period of time by improving the performance of silk fibroin agglomerated in an aqueous solution.

1 shows a conventional method for preparing an aqueous solution of silk fibroin.
Figure 2 shows a method for preparing an aqueous solution of silk fibroin according to an embodiment of the present invention.
3 is experimental data showing the aggregation inhibitory effect of the aqueous silk fibroin solution according to an embodiment of the present invention.
4 is a cell photograph showing the anti-inflammatory effect of an aqueous solution of silk fibroin according to an embodiment of the present invention.
5 is experimental data showing the IL-1β gene expression rate in the aqueous silk fibroin solution according to an embodiment of the present invention.
6 is experimental data showing the IL-12β gene expression rate in the aqueous silk fibroin solution according to an embodiment of the present invention.
7 is experimental data showing the expression rate of the COX-2 gene in the aqueous silk fibroin solution according to an embodiment of the present invention.
8 is a cell photograph showing the skin regeneration ability of an aqueous solution of silk fibroin according to an embodiment of the present invention.
9 is experimental data showing the skin regeneration ability of an aqueous solution of silk fibroin according to an embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In addition, regardless of the reference numerals, the same or corresponding components are given the same or similar reference numbers, and duplicate descriptions thereof will be omitted, and the size and shape of each component shown for convenience of description is exaggerated or reduced can be

Therefore, the configuration shown in the embodiments and drawings described in the present specification is only the most preferred embodiment of the present invention and does not represent all of the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations.

1 shows a conventional method for preparing a silk fibroin solution, and FIG. 2 shows a method for preparing a silk fibroin solution according to an embodiment of the present invention.

Referring to Figure 1, the conventional silk fibroin solution boils the cocoon in 0.02M sodium carbonate aqueous solution for 20 minutes, and then rinses with pure water to extract the fibroin protein.

The extracted silk fibroin is dissolved in a 9.3M LiBr solution at about 50 degrees Celsius for 1 hour to obtain a LiBr-Fibroin solution.

Again, the LiBr-Fibroin solution in which LiBr and fibroin are combined can be substituted with LiBr and water in an osmotic process using water to obtain an aqueous solution of fibroin.

In this case, since the amount of molecular substitution of water per ion amount of Li and Br ions is large, water is substituted in excess for the same amount of LiBr. can be obtained to have.

However, as described above, the fibroin aqueous solution obtained by using the conventional method has a problem in that gelation proceeds within about a few days to a month.

Although the cause has not been disclosed in any prior literature, the present inventors have found that the silk fibroin solution boils the cocoon in 0.02 M sodium carbonate aqueous solution for 20 minutes, and then rinses it with pure water to extract the fibroin protein, as well as sericin. The main cause was focused on the fact that the bond between the heavy chain and the light chain constituting fibroin is broken, and the light chain is dissolved together and excluded together with sericin.

More specifically, the fibroin protein consists of a combination of a non-hydrophilic heavy chain (Heavy Chain) and an intermediate hydrophilic light chain (Light Chain) as shown below.

[Amino acid sequence of heavy chain]

1 agtgssgfgp yvanggysgy eyawssesdf gtgsgagags gagagsgaga gygagvgagy

61 gagygagaga gygagagsgv asgagagags gagagsgaga gsgagagsga gagsgagags

121 gagagygaga gygagagyga gagvgygaga gvgygagagy gagagvgyga gagsgaasga

181 gagsgagags gagagsgaga gsgagagsga gagsgagags gagagsgaga gygagagvgy

241 gagagsgaas gagagsgaga gsgagagsga gagsgagags gagagsgaga gsgagagsga

301 gsgagagsga gagygagaga gvgygagaga gygagygyga gagvgygaga gsgaasgaga

361 gsgagagsga gagsgagags gagagsgags gagagsgaga gygagygagv gagygagagv

421 gygagygvga gagygagags gaasgagags gagagsgaga gsgagagsga gagsgagsga

481 gagygagags gaasgagaga gagtgssgfg pyvanggysr regyeyawss ksdfetgsga

541 asgagagags gagagsgaga gsgagagsga gaggsvsyga grgygqgags aassvssass

601 rsydysrrnv rkncgiprrq lvvkfralpc vnc

[Amino acid sequence of light chain]

1 mkpiflvllv atsayaapsv tinqysdnei prdiddgkas svisrawdyv ddtdksiail

61 nvqeilkdma sqgdyasqas avaqtagiia hlsagipgda caaanvinsy tdgvrsgnfa

121 gfrqslgpff ghvgqnlnli nqlvinpgql rysvgpalgc agggriydfe aawdailass

181 dssflneeyc ivkrlynsrn sqsnniaayi tahllppvaq vfhqsagsit dllrgvgngn

241 datglvanaq ryiaqaasqv hv

In the conventional aqueous solution of fibroin, the bond between the heavy chain and the light chain with moderate hydrophilicity is separated at a high temperature in the sericin separation process described above, and the hydrophilic light chain with a smaller molecular weight is an aqueous solution dissolved in the phase.

Therefore, the prior art thought to isolate the fibroin protein from the cocoon, but in reality only the heavy chain of the fibroin protein, not the entire fibroin protein, is extracted, and the heavy chain of the fibroin protein is Since it has overall hydrophobicity, in the conventional aqueous solution of fibroin, the tendency to bind fibroin proteins to each other is strengthened due to induction of mutual hydrophobic bonds between the hydrophobic sequences of the exposed beta-sheet structure, which leads to gelation.

However, the applicant who discovered this cause added an additional process in preparing an aqueous solution of fibroin as shown in FIG. 2 in order to prevent gelation of the fibroin protein.

More specifically, in the process of separating fibroin protein from cocoon, an aqueous phase in which sericin and light chains coexist extracted can be obtained, and sericin can be aggregated and separated and extracted by oxidation with a conventional organic acid solution.

Thereafter, neutralization is performed by adding a basic solution to an aqueous light chain solution in an acidic solution to extract a so-called neutralized and stable light chain aqueous solution.

By adding this light chain aqueous solution to the heavy chain aqueous solution obtained after the dialysis, an aqueous silk fibroin aqueous solution having extreme stability in the aqueous phase of the present invention that can delay gelation for one year or more was prepared.

More specifically, when an aqueous solution of a light chain is added to an aqueous solution of a heavy chain, a light chain with moderate hydrophilicity is bound to the outer peripheral surface of the heavy chain having a strong hydrophobic property. .

The reason why the light chain, which is moderately hydrophilic, binds to the heavy chain rather than water is, as described above, in the amino acid sequence of the heavy chain from about 40 to 500, the strong hydrophobic portion (super) -Hydrophobic) exists, and the light chain with moderate hydrophilicity is bound to the strongly hydrophobic part of the heavy chain by hydrophobic interation or Van der Waals interaction.

Due to this, the heavy chain has hydrophobic properties inside, but the light chain with moderate hydrophilicity is coated on the strong hydrophobic part of the heavy chain, It exists in a physically stable state, thereby preventing gelation.

Furthermore, since the heavy chain of the fibroin protein is stable in aqueous solution, it is possible to implement a product containing a high concentration of silk fibroin protein, which was not conventionally possible due to rapid gelation.

Basically, since the anti-inflammatory properties of fibroin protein and the skin regeneration function are physiological activities resulting from the structural binding of the protein, it was difficult to implement with an aqueous solution of fibroin protein at a low concentration as in the prior art.

More specifically, the above-described anti-inflammatory properties or skin regeneration ability can be expressed when at least the fibroin protein has a concentration of 25% or more in an aqueous solution, but if this is implemented with the prior art, gelation proceeds too quickly, so that it is not suitable for industry. It was impossible because it was difficult to apply.

In this regard, the following experimental results were obtained with reference to the experimental data showing the aggregation inhibitory effect of the aqueous silk fibroin solution according to an embodiment of the present invention shown in FIG. 3 .

The graph of FIG. 3 is a graph of experimental data for demonstrating the effect of inhibiting aggregation in aqueous solution, and shows the transmittance by irradiating a wavelength of 550 nm using a UV Spectrometer, and 550 nm than the “aggregation boundary” shown in FIG. It can be determined that aggregation occurs when the absorbance of

Looking at the results, in the case of the conventional silk fibroin control group (5%, 20%), the absorbance at 550 nm increased steeply until after about 50 days to exceed the aggregation boundary, and in this case, gelation occurred.

However, in the case of the examples (80%, 85%, 90%, 95%, 100%) of the aqueous silk fibroin solution according to an embodiment of the present invention, there was little change in the absorbance at 550 nm until about 100 days, and about 100 Although it increased at a concentration of 90% or more after 1 day, it did not reach the “aggregation boundary” even after 350 days, which indicates that gelation does not occur even after 350 days.

Therefore, as described above, the fibroin aqueous solution according to an embodiment of the present invention has a significant gelation inhibitory ability than the conventional fibroin aqueous solution.

On the other hand, in the case of the present invention, even if the concentration of fibroin protein in the aqueous solution is 90% or more, since it has stability that does not gel for at least one year, there is an effect that can implement such anti-inflammatory function or skin regeneration ability.

In order to prove this, the present applicant conducted an experiment as follows to confirm the anti-inflammatory function of the aqueous silk fibroin solution on human skin cells according to an embodiment of the present invention.

[Test method]

1. Cell Culture

RAW264.7 cells were cultured at the Korea Cell Line Bank.

For cell culture, 10,000 cells were inoculated in a 24-well plate using a cell culture dish to a medium in which 10% of fetal bovine serum (FBS) and 1% of antibiotics were added to the RPMI cell culture medium, and inoculated at 37°C for 24 hours. Stabilized in incubator.

Samples were inoculated in units of 100ul on the second day, and cell shape and related gene expression were searched after inoculation.

2. Sample processing and real-time qPCR detection method

The samples were variously treated at a concentration of about 5 to 90% (v.v) as a control (Control; aqueous solution of fibroin without improvement) and an aqueous solution of fibroin protein according to an embodiment of the present invention.

Except for the negative control group, all cells of the experimental group were treated with LPS (Lipopolysaccharide) isolated from the cell membrane of E. coli at 100 ng/ml to induce inflammation.

Induction of inflammation was confirmed by searching for changes in the shape of monocytes and the expression rate of related genes.

The above-described experimental results can be described as follows using the result data shown in FIGS. 4 to 7 .

4 is a cell photograph showing the anti-inflammatory effect of an aqueous solution of silk fibroin according to an embodiment of the present invention;

Referring to FIG. 4 , the treatment of monocytes (RAW264.7) with LPS induces an inflammatory response of the monocytes to induce macrophage cells.

The macrophage-induced cells express a star-shaped dendritic cytoplasm as observed in the cells of the intermediate LPS group.

However, in the case of the control group not treated with LPS (conventional fibroin aqueous solution treatment group), no particular dendrite was observed.

On the other hand, in the case of cells treated with LPS but treated with an aqueous fibroin solution according to an embodiment of the present invention at 10% or more, separate dendriticization was not observed.

That is, it can be seen that there is an anti-inflammatory function when the fibroin aqueous solution according to an embodiment of the present invention is treated by 10% or more.

[Quantitative gene amplification experiment]

The present applicant verified the gene expression level by realtime quantitative gene amplification experiment (Realtime qPCR) in order to explore the functional change of cells by the gene list.

The function of each gene is as follows.

1) iNOS (Nos2) gene; A gene that reflects the degree of antioxidant stress in cells.

2) Cox-2 (Ptg2) gene; A gene that reflects the expression of prostaglandin 2 as an intracellular inflammatory signal.

3) IL-1β gene; A gene that reflects the expression of interleukin 1beta, a major cytokine of inflammatory signals.

4) IL-12β gene; A gene that reflects the expression of interleukin 12 beta, a major cytokine in inflammatory signals.

5) GAPDH gene; Control gene for calculating relative gene expression rates.

In this regard, FIG. 5 is experimental data showing the IL-1β gene expression rate of the aqueous silk fibroin solution according to an embodiment of the present invention, and FIG. 6 is the IL-12β gene expression rate of the silk fibroin aqueous solution according to an embodiment of the present invention. is experimental data showing, and FIG. 7 is experimental data showing the expression rate of the COX-2 gene in the aqueous silk fibroin solution according to an embodiment of the present invention.

Referring to FIG. 5 , the IL-1β gene expression rate was higher in the experimental group treated with the fibroin aqueous solution according to an embodiment of the present invention, compared to the control group not treated with the fibroin aqueous solution according to an embodiment of the present invention.

This can be seen that the expression rate of interleukin 1beta, a major cytokine of inflammatory signals, is high in the experimental group treated with the aqueous fibroin solution according to an embodiment of the present invention, and can be interpreted to the effect that it has anti-inflammatory function.

Referring to FIG. 6 , the IL-12β gene expression rate in the experimental group treated with the aqueous fibroin solution according to an embodiment of the present invention was higher than that of the control group not treated with the aqueous fibroin solution according to an embodiment of the present invention.

This can be seen that the expression rate of interleukin 12 beta, which is a major cytokine of inflammatory signals, is high in the experimental group treated with the aqueous fibroin solution according to an embodiment of the present invention, and can be interpreted to the effect that it has anti-inflammatory function.

Referring to FIG. 7 , the COX-2 gene expression rate in the experimental group treated with the fibroin aqueous solution according to an embodiment of the present invention was higher than that of the control group not treated with the fibroin aqueous solution according to an embodiment of the present invention.

This can be seen that the expression rate of prostaglandin 2 as an intracellular inflammatory signal in the experimental group treated with the aqueous solution of fibroin according to an embodiment of the present invention is high, and it can be interpreted to the effect that it has anti-inflammatory function.

8 is a cell photograph showing the skin regeneration ability of the aqueous silk fibroin solution according to an embodiment of the present invention, and FIG. 9 is experimental data showing the skin regeneration ability of the silk fibroin aqueous solution according to an embodiment of the present invention.

Referring to Figure 8, it is a photo of the cell layer in which the damage to the cell layer is measured and the decrease in the damage interval after 24 hours is measured,

The interval of damage to the cell layer is shown as an auxiliary line with a white line, and in the case of the control treated only with the conventional aqueous silk fibroin solution, the damage interval of the cell layer did not change little, but the silk fibroin aqueous solution according to an embodiment of the present invention was treated. In the case of the experimental group, it can be seen that the cell layer damage interval was significantly reduced.

That is, referring to the experimental results, it can be seen that the aqueous silk fibroin solution of the present invention has an effective skin regeneration ability.

On the other hand, referring to FIG. 9 , the damaged region of the cell layer is graphically illustrated. The experimental group treated with 25% or more of the aqueous fibroin solution according to an embodiment of the present invention is the first control group treated with the conventional aqueous fibroin solution and the present invention It can be seen that the damaged area of the cell layer was significantly reduced compared to the second control treated with 10% of the fibroin aqueous solution according to an embodiment of the present invention.

Therefore, in light of these experimental results, it can be seen that the skin regeneration ability is rapidly increased when 25% or more of the fibroin aqueous solution according to an embodiment of the present invention is treated.

In the above, the embodiment of the present invention has been mainly described, but this is only an example and does not limit the present invention. It will be appreciated that various modifications and applications not exemplified above are possible. For example, each component specifically shown in the embodiment of the present invention may be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (9)

delete delete delete delete delete delete delete delete extracting fibroin from the cocoon;
dissolving the fibroin into a LiBr solution;
dialysis of LiBr salt in an osmosis process to obtain a medium chain aqueous solution;
extracting the light chain from the aqueous solution from which the fibroin is extracted in the step of extracting the fibroin from the cocoon;
Neutralizing the extracted light chain aqueous solution by adding a basic solution to the extracted light chain aqueous solution and
Method for producing an aqueous solution of silk fibroin, characterized in that by adding the neutralized aqueous solution of light chains to the aqueous solution of heavy chains to delay the gelation of the aqueous solution of heavy chains.

Images