Method for specific cleavage of C alpha-C bond and side chain of protein and peptide, and method for determining amino acid sequence

A method for determining an amino acid sequence of a protein or a peptide, comprising:

• irradiating a protein or a peptide with laser light in the presence of at least one hydroxynitrobenzoic acid selected from the group consisting of:
• 3-hydroxy-2-nitrobenzoic acid:
• 4-hydroxy-3-nitrobenzoic acid:
• 5-hydroxy-2-nitrobenzoic acid:
• 3-hydroxy-5-nitrobenzoic acid:
• and
• 4-hydroxy-2-nitrobenzoic acid:
• to specifically cleave a Cα-C bond of a peptide backbone and/or a side chain bond;
• and
• analyzing generated fragment ions by mass spectrometry,
• wherein the hydroxynitrobenzoic acid promotes the specific cleavage of the Cα-C bond of the peptide backbone and/or the side chain bond.

A method for determining an amino acid sequence of a protein or a peptide, comprising:

• irradiating a protein or a peptide with laser light in the presence of at least one hydroxynitrobenzoic acid selected from the group consisting of 3-hydroxy-2-nitrobenzoic acid, 4-hydroxy-3-nitrobenzoic acid, 5-hydroxy-2-nitrobenzoic acid, 3-hydroxy-5-nitrobenzoic acid, and 4-hydroxy-2-nitrobenzoic acid as a matrix to specifically cleave a Cα-C bond of a peptide backbone and/or a side chain bond;
• and
• analyzing generated fragment ions by MALDI mass spectrometry,
• wherein the hydroxynitrobenzoic acid promotes the specific cleavage of the Cα-C bond of the peptide backbone and/or the side chain bond.