The inhibitory effect of salicylate on the acetylation of human albumin by acetylsalicylic acid

The transacetylation reaction between aspirin and human serum albumin (HSA) is partially inhibited by pharmacologic concentrations of salicylate anion. This inhibition was noted with respect to the inhibition of enhanced acetrizoate binding and by autoradiography of peptide maps of aspirin‐acetylated HSA. The acetylation of a single lysine residue in a peptide 7“A” has been found to be responsible for the previously reported, enhanced binding of acetrizoate by aspirin‐altered albumin. At least 5 other peptides are also acetylated, but they do not influence acetrizoate binding. The results are discussed in view of the unique pharmacologic activities of aspirin, and also, with respect to biologic reactions ascribed to aspirin therapy.