Method for detecting post-translational modification of peptides

Abstract

Method is described for sequencing polypeptides by forming peptide ladders comprising a series of polypeptides in which adjacent members of the series vary by one amino acid residue and determining the identity and position of each amino acid in the polypeptide by mass spectroscopy.

1 - 33 . (canceled)  
     
     
         34 . A probe for performing laser desorption mass spectrometry having a matrix of α-cyano-4-hydroxy-cinnamic acid.  
     
     
         35 . A probe of claim  1  where the matrix further comprises a sample.  
     
     
         36 . A probe of claim  1  wherein the sample comprises a protein.  
     
     
         37 . A probe of claim  1  where the sample comprises a protein ladder.  
     
     
         38 . A probe of claim  1  made by mixing the α-cyano-4-hydroxy-cinnamic acid with acetonitrile prior to drying the matrix onto the probe.  
     
     
         39 . A probe for performing laser desorption mass spectrometry manufactured by contacting the probe with a solution comprising α-cyano-4-hydroxy-cinnamic acid.  
     
     
         40 . A probe of  claim 39  wherein the solution further comprises acetonitrile.  
     
     
         41 . A probe of  claim 39  wherein the solution further comprises trifluoroacetic acid.