The performic acid oxidation of egg-white lysozyme

Abstract

The performic acid oxidation of egg-white lysozyme has been studied using amounts of oxidant varying from 0.5 mole to 3 moles excess. The results show that excess performic acid causes substantial peptide bond hydrolysis both at the tryptophan residues and at other places in the molecule. The yields of kynurenin vary with the amount of oxidant and are greater than those found for the performic acid oxidation of tryptophan itself. The results also show that the tryptophyl residues are more susceptible to oxidation than are the cystine residues and that oxidations with less than stoichiometric amounts of oxidant produce an intermediate from tryptophyl residues which does not give kynurenin upon acid hydrolysis.