Sulphitolysis in keratinolysis. Biochemical proof

The presence of S-sulphocysteine in filtrates of the dermatophyte Keratinomyces ajelloi growing on human hair in a culture medium buffered by pH 7·4 by phosphates was demonstrated by means of ion exchange chromatography techniques. S-sulphocysteine being destroyed during acidic hydrolysis was identified after enzymic hydrolysis of dialyzed and lyophilized filtrates. This result indicates that sulphitolysis occurs during keratinolysis performed by K. ajelloi. As thiosulphuric esters were shown present in hair perforations made by Microsporum gypseum, we think sulphitolysis is a common mechanism developed by dermatophytes to attack keratin.