Acetylating agents such as acetic anhydride react preferentially with primary amines, iodoacetate reacts preferentially with sulfhydryl groups (see Tools of Biochemistry 5B), and ATP-dependent kinases prefentially add a phosphoryl group to side-chain hydroxyl or phenolic -OH groups. Which amino acid side chains, or main chain groups, in a polypeptide are most likely to be modified by treatment with:
a. Acetic anhydride
b. Iodoacetate
c. A kinase + ATP