Abstract: The present invention relates to methods for the characterization of enzymes or of enzyme-compound complexes, wherein the enzyme is obtained from a protein preparation with the help of at least one broad spectrum ligand immobilized on a solid support and wherein the enzyme is characterized by mass spectrometry. These methods are useful for the screening of non-immobilized compound libraries, selectivity profiling of lead compounds and mechanism of action studies in living cells.

Abstract: A peptide having the amino acid sequence H2N—X1—R—X3—X2—COOH  (formula I) wherein X1 is either zero or X1 and/or X2 are a residue representing at least five amino acid residues (symbolized in the one letter amino acid code), preferably naturally occurring amino acids, with the proviso that X1 and/or X2 contain at least one basic amino acid residue immediately followed by a hydrophobic amino acid residue and X1 and/or X2 contain at least one glutamine residue.

Abstract: A peptide having the amino acid sequence

Abstract: The present invention relates to a quick method for the qualitative and quantitative medical-diagnostic analysis on the protein level of the substitution of single amino acids with pathogenic and non-pathogenic effects on the organism. The medical-diagnostic analysis is performed by a combination of enzymatic or chemical cleavage of the isolated peptide, chromatographical separation of the fragments and analysis by mass spectrometry, both direct LC/MS and indirect MALDI-MS, and analysis by capillary electrophoresis. By comparing protein samples from healthy humans with those of ill humans, the method described is suitable for establishing new, as yet unknown mutations and quantifying the expression and incorporation of wild type to mutant.