Patent ID: 7670795

Claim:
A method for characterizing the activity of an enzyme or enzyme mixture comprising an acetyl transferase or a deacetylase, the method comprising: (a) incubating the enzyme or enzyme mixture in vitro with a polypeptide substrate under conditions that allow acetylation and/or deacetylation of the polypeptide substrate to add acetyl groups to or remove acetyl groups from the polypeptide substrate to generate an enzymatically acetylated and/or deacetylated polypeptide, wherein the polypeptide substrate is a peptide fragment of a full-length protein; (b) reacting the enzymatically acetylated and/or deacetylated polypeptide with an acyl-containing substance that non-enzymatically reacts with the polypeptide to add acyl groups to the polypeptide to generate a fully acylated polypeptide; wherein the acyl group of the acyl-containing substance differs in molecular weight from the added or removed acetyl groups of the enzymatically acetylated and/or deacetylated protein or peptide; and (c) subjecting the fully acylated polypeptide to mass spectrometry to determine amino acid positions of enzymatically added or removed acetyl groups on the polypeptide and percent enzymatic acetylation or deacetylation at each of the amino acid positions of enzymatically added or removed acetyl groups.