The complete amino acid sequence of hirudin, a thrombin specific inhibitor

Color carboxymethylation of cysteine residues with a new chromophoric reagent dimethylaminoazobenzene iodoacetamide, was applied to the micro‐sequence analysis of hirudin, a thrombin specific inhibitor. Six cysteine residues of the reduced hirudin were detected as colored phenylthiohydantoin derivative and 3 tryptic peptides of hirudin (all containing cysteines) were isolated as colored peptide. The complete hirudin sequence, including 6 uncertain positions left in the previous report [Petersen T.E. (1976) in: Protides of the Biological Fluids; 23rd Colloquium, pp. 145, Pergamon Press, London] was established.