Fluorescent amyloid Abeta peptides and uses thereof

Abstract

Disclosed herein are aggregating amyloid Aβ peptides which are covalently bonded (for example, at a cysteine amino acid residue) to a fluorescent label, and methods for their use.

What is claimed is:  
     
         1 . A method for generating an aggregating amyloid Aβ peptide, said method comprising: 
 (a) generating an amyloid Aβ peptide comprising a cysteine amino acid substitution;  
 (b) covalently bonding a fluorescent label to said peptide at said cysteine amino acid; and  
 (c) determining whether said peptide is capable of aggregating with another Aβ peptide.  
 
     
     
         2 . The method of  claim 1 , wherein said cysteine substitution occurs at an internal amino acid.  
     
     
         3 . A method for identifying a compound capable of affecting the aggregation of Aβ amyloid peptide, said method comprising 
 (a) providing a sample of Aβ amyloid peptide;  
 (b) contacting said sample with (i) an aggregating amyloid Aβ peptide to which is covalently bonded a fluorescent label; and (ii) a candidate compound; and  
 (c) measuring association of said fluorescent label with said sample, a change in the level of fluorescent label found in association with said sample relative to a control sample lacking said candidate compound being an indication that said compound is capable of affecting Aβ amyloid peptide aggregation.  
 
     
     
         4 . The method of  claim 3 , wherein said fluorescent label is covalently bonded to a cysteine amino acid.  
     
     
         5 . The method of  claim 3 , wherein said sample comprises unlabeled Aβ amyloid peptide bound to a solid support and said aggregation is measured by association of said fluorescent label with said solid support.  
     
     
         6 . A method for identifying a compound capable of affecting the aggregation of Aβ amyloid peptide, said method comprising 
 (a) providing a sample of an aggregating amyloid Aβ peptide to which is covalently bonded a fluorescent label;  
 (b) contacting said sample with a candidate compound; and  
 (c) measuring the ability of said peptide to aggregate, a change in the amount of aggregated peptide in the presence of said candidate compound relative to a sample lacking said compound being an indication that said compound is capable of affecting Aβ amyloid peptide aggregation.  
 
     
     
         7 . The method of  claim 6 , wherein said fluorescent label is covalently bonded to a cysteine amino acid.  
     
     
         8 . The method of  claim 3  or  6 , wherein said compound inhibits Aβ amyloid peptide aggregation.  
     
     
         9 . The method of  claim 4  or  7 , wherein said cysteine amino acid replaces an internal amino acid in a wild type amyloid Aβ peptide.  
     
     
         10 . The method of  claim 3  or  6 , wherein aggregation is measured by centrifugation, gel filtration, or fluorescence resonance energy transfer (FRET) analysis.  
     
     
         11 . The method of  claim 4  or  7 , wherein said aggregating Aβ peptide comprises a cysteine amino acid covalently bonded to a fluorescent label at any of amino acid positions 4, 7, 25, or 34 of SEQ ID NO: 1 or SEQ ID NO: 2.  
     
     
         12 . The method of  claim 3  or  6 , wherein said fluorescent label is a thiol-reactive fluorescent dye.