WO2012175458A1 - A method for the identification of beta-sheet aggregated protein ligands - Google Patents

A method for the identification of beta-sheet aggregated protein ligands Download PDF

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Publication number
WO2012175458A1
WO2012175458A1 PCT/EP2012/061621 EP2012061621W WO2012175458A1 WO 2012175458 A1 WO2012175458 A1 WO 2012175458A1 EP 2012061621 W EP2012061621 W EP 2012061621W WO 2012175458 A1 WO2012175458 A1 WO 2012175458A1
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WIPO (PCT)
Prior art keywords
protein
beta
tau
aggregated protein
peptide
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PCT/EP2012/061621
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French (fr)
Inventor
Edilio BORRONI
Christian Czech
Arnulf DORN
Luca Gobbi
Valerie GOETSCHY-MEYER
Fiona Grueninger
Doris Roth
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F. Hoffmann-La Roche Ag
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Priority to RU2013158623/15A priority Critical patent/RU2013158623A/en
Priority to JP2014516297A priority patent/JP2014520270A/en
Priority to CN201280030461.2A priority patent/CN103649757A/en
Priority to CA2837957A priority patent/CA2837957A1/en
Priority to KR1020137034019A priority patent/KR20140026565A/en
Priority to MX2013014006A priority patent/MX2013014006A/en
Priority to BR112013031498A priority patent/BR112013031498A2/en
Priority to EP12728527.8A priority patent/EP2724161A1/en
Publication of WO2012175458A1 publication Critical patent/WO2012175458A1/en
Priority to US14/137,399 priority patent/US20140363898A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/68—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids
    • G01N33/6863—Cytokines, i.e. immune system proteins modifying a biological response such as cell growth proliferation or differentiation, e.g. TNF, CNF, GM-CSF, lymphotoxin, MIF or their receptors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/68—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/68—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids
    • G01N33/6893—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids related to diseases not provided for elsewhere
    • G01N33/6896—Neurological disorders, e.g. Alzheimer's disease
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
    • G01N2333/435—Assays involving biological materials from specific organisms or of a specific nature from animals; from humans
    • G01N2333/46—Assays involving biological materials from specific organisms or of a specific nature from animals; from humans from vertebrates
    • G01N2333/47—Assays involving proteins of known structure or function as defined in the subgroups
    • G01N2333/4701—Details
    • G01N2333/4709—Amyloid plaque core protein
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2500/00—Screening for compounds of potential therapeutic value
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2500/00—Screening for compounds of potential therapeutic value
    • G01N2500/02—Screening involving studying the effect of compounds C on the interaction between interacting molecules A and B (e.g. A = enzyme and B = substrate for A, or A = receptor and B = ligand for the receptor)

Definitions

  • the present invention relates to a method for the identification of ligands which bind aggregated proteins forming beta sheets.
  • Alzheimer's disease This will be a valuable tool for diagnosis and patients stratification.
  • Tau imaging would be a useful biomarker for projects targeting tau pathology and neurodegeneration.
  • PET Positron Emission Tomography
  • the method of the present invention is based on the finding that Thiazine Red R (CAS Nr. 2150-33-6) bound to beta-sheet aggregates shows a strong increase of fluorescence compared to Thiazine Red R bound to monomers forming the beta- sheet aggregates.
  • the term "beta-sheet aggregated protein" is used herein to refer to proteins which form aggregates having ⁇ -sheet structure. Tau protein, alpha-synuclein protein and ⁇ peptide form aggregates having a ⁇ -sheet structure.
  • protein refers to a polymer of amino acids, and not to a specific length. Thus, peptides, oligopeptides and protein fragments are included within the definition of polypeptide.
  • protein is interchangeably used with the term "polypeptide”.
  • tau protein is used herein to refer to native sequence tau protein from any animal, e.g. mammalian, species, including humans, and tau variants (which are further defined below).
  • the tau polypeptides may be isolated from a variety of sources, including human tissue types or prepared by recombinant and/or synthetic methods. Natural or recombinantly produced tau protein can be used in this assay.
  • a "recombinant protein” is a protein isolated, purified, or identified by virtue of expression in a heterologous cell, said cell having been transduced or transfected, either transiently or stably, with a recombinant expression vector engineered to drive expression of the protein in the host cell.
  • Recombinant tau can be produced in procaryotic cells e.g. E. coli, in yeast e.g. S. pombe or in eukaryotic cells e.g. HEK 293, Sf9 insect cells.
  • procaryotic cells e.g. E. coli
  • yeast e.g. S. pombe
  • eukaryotic cells e.g. HEK 293, Sf9 insect cells.
  • Sf9 insect cells are used for high expression of
  • the tau protein used in the assay may be purified.
  • purified refers to polypeptides, that are removed from their natural environment or from the source of recombinant production, isolated or separated, and are at least 60% and more preferably at least 80% free from other components, e.g. membranes and microsomes, with which they are naturally associated.
  • Native sequence tau refers to a polypeptide having the same amino acid sequence as a tau polypeptide occurring in nature regardless of its mode of preparation.
  • a native sequence tau may be isolated from nature, or prepared by recombinant and/or synthetic methods.
  • the term "native sequence tau” specifically encompasses naturally occurring truncated or secreted forms, naturally occurring variant forms (e.g. alternatively spliced forms), and naturally occurring allelic variants of tau.
  • the identifier of the human tau polypeptide in the NCBI database is NP_005901 (Seq. Id. No. 1).
  • tau variant refers to amino acid sequence variants of a native sequence tau, containing one or more amino acid substitution and/or deletion and/or insertion in the native sequence.
  • the amino acid sequence variants generally have at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, most preferably at least about 95% sequence identity with the amino acid sequence of a native sequence tau.
  • ⁇ peptide is used herein to refer to native sequence ⁇ peptide from any animal, e.g. mammalian, species, including humans, and ⁇ peptide variants (which are further defined below).
  • the ⁇ peptide may be isolated from a variety of sources, including human tissue types or prepared by recombinant and/or synthetic methods.
  • Natural or recombinantly produced ⁇ peptide can be used in this assay.
  • a "recombinant protein” is a protein isolated, purified, or identified by virtue of expression in a heterologous cell, said cell having been transduced or transfected, either transiently or stably, with a recombinant expression vector engineered to drive expression of the protein in the host cell.
  • Recombinant ⁇ peptide can be produced in procaryotic cells e.g. E. coli, in yeast e.g. S .pombe or in eukaryotic cells e.g. HEK 293, Sf9 insect cells.
  • the ⁇ peptide used in the assay may be purified.
  • purified refers to polypeptides, that are removed from their natural environment or from the source of recombinant production, isolated or separated, and are at least 60% and more preferably at least 80% free from other components, e.g. membranes and microsomes, with which they are naturally associated.
  • Native sequence ⁇ peptide refers to a polypeptide having the same amino acid sequence as an ⁇ peptide occurring in nature regardless of its mode of preparation. It is of note that " ⁇ peptide” has several naturally occurring forms, whereby the human forms are referred to as ⁇ 39, ⁇ 40, ⁇ 41, ⁇ 42 and ⁇ 43. The most prominent form, ⁇ 42, has the amino acid sequence (starting from the N-terminus):
  • DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA (Seq. Id. No. 3).
  • ⁇ 41, ⁇ 40, ⁇ 39 the C-terminal amino acids A, IA and VIA are missing, respectively.
  • an additional threonine residue is comprised at the C-terminus of the above depicted sequence (Seq. Id. No. 3).
  • the preferred ⁇ peptide used in the present assay is ⁇ 40 having the amino acid sequence given in Seq. Id. No. 4.
  • a native sequence ⁇ peptide may be isolated from nature, or prepared by recombinant and/or synthetic methods.
  • the term "native sequence ⁇ peptide” specifically encompasses naturally occurring truncated or secreted forms, naturally occurring variant forms and naturally occurring allelic variants of ⁇ peptide.
  • the term " ⁇ peptide variant” refers to amino acid sequence variants of a native sequence ⁇ peptide, containing one or more amino acid substitution and/or deletion and/or insertion in the native sequence.
  • the amino acid sequence variants generally have at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, most preferably at least about 95% sequence identity with the amino acid sequence of a native sequence ⁇ peptide.
  • alpha- synuclein protein is used herein to refer to native sequence alpha- synuclein protein from any animal, e.g. mammalian, species, including humans, and alpha- synuclein variants (which are further defined below).
  • the alpha- synuclein polypeptides may be isolated from a variety of sources, including human tissue types or prepared by recombinant and/or synthetic methods. Natural or recombinantly produced alpha-synuclein protein can be used in this assay.
  • recombinant protein is a protein isolated, purified, or identified by virtue of expression in a heterologous cell, said cell having been transduced or transfected, either transiently or stably, with a recombinant expression vector engineered to drive expression of the protein in the host cell.
  • Recombinant alpha-synuclein can be produced in procaryotic cells e.g. E. coli, in yeast e.g. S. pombe or in eukaryotic cells e.g. HEK 293, Sf9 insect cells.
  • Sf9 insect cells are used for high expression of recombinant alpha-synuclein.
  • the alpha-synuclein protein used in the assay may be purified.
  • purified refers to polypeptides, that are removed from their natural environment or from the source of recombinant production, isolated or separated, and are at least 60% and more preferably at least 80% free from other components, e.g. membranes and microsomes, with which they are naturally associated.
  • Native sequence alpha-synuclein refers to a polypeptide having the same amino acid sequence as an alpha-synuclein polypeptide occurring in nature regardless of its mode of preparation. A native sequence alpha-synuclein may be isolated from nature, or prepared by recombinant and/or synthetic methods.
  • nuclein specifically encompasses naturally occurring truncated or secreted forms, naturally occurring variant forms (e.g. alternatively spliced forms), and naturally occurring allelic variants of alpha-synuclein.
  • amino acid sequence of human alpha-synuclein polypeptide is given in Seq. Id. No. 2.
  • alpha-synuclein variant refers to amino acid sequence variants of a native sequence alpha-synuclein, containing one or more amino acid substitution and/or deletion and/or insertion in the native sequence.
  • the amino acid sequence variants generally have at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, most preferably at least about 95% sequence identity with the amino acid sequence of a native sequence alpha-synuclein.
  • compound is used herein in the context of a “test compound” or a “tracer candidate compound” described in connection with the assays of the present invention.
  • these compounds comprise organic or inorganic compounds, derived synthetically or from natural sources.
  • the compounds include inorganic or organic compounds such as, but not limited to, polynucleotides, lipids or hormone analogs that are characterized by relatively low molecular weights. Short description of the figure
  • Fig. 1 shows a saturation analysis of Thiazin red R for aggregated and monomeric proteins. There are two different binding sites for Thiazin-red on each of the aggregated protein. Kd are determined for both binding sites (K ⁇ jl, K ⁇ j2)
  • Experimental Part Recombinant human-microtubule associated protein Tau purified from E.coli is aggregated at a concentration of 5 ⁇ with Arachidonic Acid (100 ⁇ ) in Tris 10 mM pH8, 24h at 37°C.
  • Synthetic AB40 is aggregated with Arachidonic Acid (100 ⁇ ) in Tris 10 mM pH8, for three days at 37°C, under shaking at 150 rpm.
  • Human recombinant- Alpha- synuclein-purified from E.coli is aggregated with Arachidonic Acid (100 ⁇ ) in Tris 10 mM pH 8, for 5 days at 37°C, under shaking at 150 rpm.
  • a saturation analysis of Thiazin-red to the aggregated proteins is done to determine the affinity (Kd) of the Thiazin-red to the aggregated protein.
  • Table 1 shows the affinity constants of Thiazin-red for aggregated tau, Abeta and alpha-synuclein. The results show that there are two binding sites with different affinity on each aggregated protein for Thiazin-red.
  • Thiazin-red will be added at the concentration corresponding to the Kd to the respective aggregated protein binding site, to induce a fluorescent signal that can be inhibited by the addition of a displacer compound
  • the compound is added at different concentrations in the assay ranging from 0.3 nM to 10000 nM.
  • Assay is performed in Perkin Elmer OptiPlate 384, black, 45 ul assay volume, assay buffer is DPBS no CaCl 2 no MgCl 2 (GIBCO N. 14020). Tested compounds are diluted in DMSO and 2 ⁇ is added to the assay (5% DMSO final). Assay is started by the addition of the aggregated protein (competitive condition). Plates are shortly shacked (1 min with Sterico variomag teleshake) and incubated for 30 min at room temperature. Measurement are done with En:Vision (Perkin Elmer), at Excitation 531 nm / Emission 595 nm.
  • Table 1 shows the affinity constants of different compounds against aggregated tau, Abeta and alpha-synuclein against the high affinity binding site.

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Abstract

The present invention provides an assay for the identification of beta-sheet aggregated protein ligands using Thiazine Red R.

Description

A METHOD FOR THE IDENTIFICATION OF BETA-SHEET AGGREGATED
PROTEIN LIGANDS
The present invention relates to a method for the identification of ligands which bind aggregated proteins forming beta sheets.
Tau protein aggregates in the brain of Alzheimer's patients correlate very well with the progression of neurodegeneration disease and could be useful as early imaging marker for a neurodegenerative process. There are other neurodegenerative diseases that show aggregation of tau. In combination with amyloid-beta imaging tauopathies could be differentiated from
Alzheimer's disease. This will be a valuable tool for diagnosis and patients stratification. Tau imaging would be a useful biomarker for projects targeting tau pathology and neurodegeneration.
Therefore, there is a need for a method for the identification of PET (Positron Emission Tomography) imaging ligands for specific imaging of tau aggregates in Alzheimer's disease patients or in other tauopathies.
The method of the present invention is based on the finding that Thiazine Red R (CAS Nr. 2150-33-6) bound to beta-sheet aggregates shows a strong increase of fluorescence compared to Thiazine Red R bound to monomers forming the beta- sheet aggregates. The term "beta-sheet aggregated protein" is used herein to refer to proteins which form aggregates having β-sheet structure. Tau protein, alpha-synuclein protein and Αβ peptide form aggregates having a β-sheet structure.
The term "protein" as used herein, refers to a polymer of amino acids, and not to a specific length. Thus, peptides, oligopeptides and protein fragments are included within the definition of polypeptide. The term "protein" is interchangeably used with the term "polypeptide".
The term "tau protein" is used herein to refer to native sequence tau protein from any animal, e.g. mammalian, species, including humans, and tau variants (which are further defined below). The tau polypeptides may be isolated from a variety of sources, including human tissue types or prepared by recombinant and/or synthetic methods. Natural or recombinantly produced tau protein can be used in this assay. A "recombinant protein" is a protein isolated, purified, or identified by virtue of expression in a heterologous cell, said cell having been transduced or transfected, either transiently or stably, with a recombinant expression vector engineered to drive expression of the protein in the host cell. Recombinant tau can be produced in procaryotic cells e.g. E. coli, in yeast e.g. S. pombe or in eukaryotic cells e.g. HEK 293, Sf9 insect cells. Preferably, Sf9 insect cells are used for high expression of
recombinant tau. The tau protein used in the assay may be purified. The term "purified" as used herein refers to polypeptides, that are removed from their natural environment or from the source of recombinant production, isolated or separated, and are at least 60% and more preferably at least 80% free from other components, e.g. membranes and microsomes, with which they are naturally associated.
"Native sequence tau" refers to a polypeptide having the same amino acid sequence as a tau polypeptide occurring in nature regardless of its mode of preparation. A native sequence tau may be isolated from nature, or prepared by recombinant and/or synthetic methods. The term "native sequence tau" specifically encompasses naturally occurring truncated or secreted forms, naturally occurring variant forms (e.g. alternatively spliced forms), and naturally occurring allelic variants of tau. The identifier of the human tau polypeptide in the NCBI database is NP_005901 (Seq. Id. No. 1).
The term "tau variant" refers to amino acid sequence variants of a native sequence tau, containing one or more amino acid substitution and/or deletion and/or insertion in the native sequence. The amino acid sequence variants generally have at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, most preferably at least about 95% sequence identity with the amino acid sequence of a native sequence tau.
The term "Αβ peptide" is used herein to refer to native sequence Αβ peptide from any animal, e.g. mammalian, species, including humans, and Αβ peptide variants (which are further defined below). The Αβ peptide may be isolated from a variety of sources, including human tissue types or prepared by recombinant and/or synthetic methods.
Natural or recombinantly produced Αβ peptide can be used in this assay. A "recombinant protein" is a protein isolated, purified, or identified by virtue of expression in a heterologous cell, said cell having been transduced or transfected, either transiently or stably, with a recombinant expression vector engineered to drive expression of the protein in the host cell. Recombinant Αβ peptide can be produced in procaryotic cells e.g. E. coli, in yeast e.g. S .pombe or in eukaryotic cells e.g. HEK 293, Sf9 insect cells. The Αβ peptide used in the assay may be purified. The term "purified" as used herein refers to polypeptides, that are removed from their natural environment or from the source of recombinant production, isolated or separated, and are at least 60% and more preferably at least 80% free from other components, e.g. membranes and microsomes, with which they are naturally associated. "Native sequence Αβ peptide" refers to a polypeptide having the same amino acid sequence as an Αβ peptide occurring in nature regardless of its mode of preparation. It is of note that "Αβ peptide" has several naturally occurring forms, whereby the human forms are referred to as Αβ39, Αβ40, Αβ41, Αβ42 and Αβ43. The most prominent form, Αβ42, has the amino acid sequence (starting from the N-terminus):
DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA (Seq. Id. No. 3). In Αβ41, Αβ40, Αβ39, the C-terminal amino acids A, IA and VIA are missing, respectively. In the Αβ43- form an additional threonine residue is comprised at the C-terminus of the above depicted sequence (Seq. Id. No. 3). The preferred Αβ peptide used in the present assay is Αβ40 having the amino acid sequence given in Seq. Id. No. 4.
A native sequence Αβ peptide may be isolated from nature, or prepared by recombinant and/or synthetic methods. The term "native sequence Αβ peptide" specifically encompasses naturally occurring truncated or secreted forms, naturally occurring variant forms and naturally occurring allelic variants of Αβ peptide. The term "Αβ peptide variant" refers to amino acid sequence variants of a native sequence Αβ peptide, containing one or more amino acid substitution and/or deletion and/or insertion in the native sequence. The amino acid sequence variants generally have at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, most preferably at least about 95% sequence identity with the amino acid sequence of a native sequence Αβ peptide. The term " alpha- synuclein protein" is used herein to refer to native sequence alpha- synuclein protein from any animal, e.g. mammalian, species, including humans, and alpha- synuclein variants (which are further defined below). The alpha- synuclein polypeptides may be isolated from a variety of sources, including human tissue types or prepared by recombinant and/or synthetic methods. Natural or recombinantly produced alpha-synuclein protein can be used in this assay. A
"recombinant protein" is a protein isolated, purified, or identified by virtue of expression in a heterologous cell, said cell having been transduced or transfected, either transiently or stably, with a recombinant expression vector engineered to drive expression of the protein in the host cell. Recombinant alpha-synuclein can be produced in procaryotic cells e.g. E. coli, in yeast e.g. S. pombe or in eukaryotic cells e.g. HEK 293, Sf9 insect cells. Preferably, Sf9 insect cells are used for high expression of recombinant alpha-synuclein. The alpha-synuclein protein used in the assay may be purified. The term "purified" as used herein refers to polypeptides, that are removed from their natural environment or from the source of recombinant production, isolated or separated, and are at least 60% and more preferably at least 80% free from other components, e.g. membranes and microsomes, with which they are naturally associated. "Native sequence alpha-synuclein" refers to a polypeptide having the same amino acid sequence as an alpha-synuclein polypeptide occurring in nature regardless of its mode of preparation. A native sequence alpha-synuclein may be isolated from nature, or prepared by recombinant and/or synthetic methods. The term "native sequence alpha-synuclein" specifically encompasses naturally occurring truncated or secreted forms, naturally occurring variant forms (e.g. alternatively spliced forms), and naturally occurring allelic variants of alpha-synuclein. The amino acid sequence of human alpha-synuclein polypeptide is given in Seq. Id. No. 2.
The term "alpha-synuclein variant" refers to amino acid sequence variants of a native sequence alpha-synuclein, containing one or more amino acid substitution and/or deletion and/or insertion in the native sequence. The amino acid sequence variants generally have at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, most preferably at least about 95% sequence identity with the amino acid sequence of a native sequence alpha-synuclein.
The term "compound" is used herein in the context of a "test compound" or a "tracer candidate compound" described in connection with the assays of the present invention. As such, these compounds comprise organic or inorganic compounds, derived synthetically or from natural sources. The compounds include inorganic or organic compounds such as, but not limited to, polynucleotides, lipids or hormone analogs that are characterized by relatively low molecular weights. Short description of the figure
Fig. 1 shows a saturation analysis of Thiazin red R for aggregated and monomeric proteins. There are two different binding sites for Thiazin-red on each of the aggregated protein. Kd are determined for both binding sites (K<jl, K<j2) A: Tau B: Abeta C: Alpha-synuclein
Experimental Part Recombinant human-microtubule associated protein Tau purified from E.coli is aggregated at a concentration of 5 μΜ with Arachidonic Acid (100 μΜ) in Tris 10 mM pH8, 24h at 37°C. Synthetic AB40 is aggregated with Arachidonic Acid (100 μΜ) in Tris 10 mM pH8, for three days at 37°C, under shaking at 150 rpm.
Human recombinant- Alpha- synuclein-purified from E.coli is aggregated with Arachidonic Acid (100 μΜ) in Tris 10 mM pH 8, for 5 days at 37°C, under shaking at 150 rpm.
A saturation analysis of Thiazin-red to the aggregated proteins is done to determine the affinity (Kd) of the Thiazin-red to the aggregated protein. Table 1 shows the affinity constants of Thiazin-red for aggregated tau, Abeta and alpha-synuclein. The results show that there are two binding sites with different affinity on each aggregated protein for Thiazin-red.
Thiazin-red will be added at the concentration corresponding to the Kd to the respective aggregated protein binding site, to induce a fluorescent signal that can be inhibited by the addition of a displacer compound
To determine the affinity of a displacer compound to the Thiazin -red binding sites of the aggregated proteins, the compound is added at different concentrations in the assay ranging from 0.3 nM to 10000 nM.
In parallel, auto fluorescence of the compound is measured together with the aggregated proteins, but without Thiazin-red. As negative control, ligand and aggregated protein is used and as positive control, Thiazin-red, reference compound with known activity and aggregated protein is used.
Assay is performed in Perkin Elmer OptiPlate 384, black, 45 ul assay volume, assay buffer is DPBS no CaCl2 no MgCl2 (GIBCO N. 14020). Tested compounds are diluted in DMSO and 2 μΐ is added to the assay (5% DMSO final). Assay is started by the addition of the aggregated protein (competitive condition). Plates are shortly shacked (1 min with Sterico variomag teleshake) and incubated for 30 min at room temperature. Measurement are done with En:Vision (Perkin Elmer), at Excitation 531 nm / Emission 595 nm.
Table 1 shows the affinity constants of different compounds against aggregated tau, Abeta and alpha-synuclein against the high affinity binding site.
Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, the descriptions and examples should not be construed as limiting the scope of the invention. The disclosures of all patent and scientific literature cited herein are expressly incorporated in their entirety by reference.

Claims

Claims
1. A method for the identification of a beta-sheet aggregated protein ligand comprising: a) contacting a beta-sheet aggregated protein with Thiazine Red R and a compound, b) measuring Thiazine Red R fluorescence in the mixture of step a), wherein a
decreased Thiazine Red R fluorescence in the mixture of step a) compared to a blank is indicative for a beta-sheet aggregated protein ligand.
2. The method of claim 1, wherein the beta-sheet aggregated protein is selected from tau protein, Αβ peptide and alpha-synuclein protein.
3. The method of claim 1 or 2, wherein the beta-sheet aggregated protein is tau protein or
Αβ40 peptide, preferably human tau protein or human Αβ40 peptide.
4. The method of claim 1 to 3, wherein the Thiazine Red R fluorescence is measured at Excitation 531 nm / Emission 595 nm.
5. The method of claim 1 to 4, wherein the beta-sheet aggregated protein is a
recombinantly produced beta-sheet aggregated protein.
6. The method of claim 1 to 5, wherein the blank comprises the beta-sheet aggregated protein and Thiazine Red R.
7. The method of claim 1 to 6, wherein the compound is added to the mixture of step a) in increasing concentrations in order to determine the IC50 of the test compound.
PCT/EP2012/061621 2011-06-22 2012-06-19 A method for the identification of beta-sheet aggregated protein ligands WO2012175458A1 (en)

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KR1020137034019A KR20140026565A (en) 2011-06-22 2012-06-19 A method for the identification of beta-sheet aggregated protein ligands
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BR112013031498A BR112013031498A2 (en) 2011-06-22 2012-06-19 method for identification of a beta-leaf aggregated protein ligand and use of thiazine red r
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