Hair digestion by a keratinase of Trichophyton mentagrophytes.

Abstract

The extracellular keratinase of Trichophyton mentagrophytes var. granulosum readily digests unautoclaved white guinea pig hair. Incubation with the enzyme for only three hours results in the release of 10.3% of the hair protein into the reaction fluid. Incubation with the keratinase removes the medulla of the hair and results in the appearance of many fissures in the cortex. The keratinase has a pH optimum of 7.0, its optimum temperature lies between 43° and 54° C, and optimum ionic strength is at 0.05 M NaCl in buffer. The keratinolytic activity is activated by barium, calcium, magnesium and selenium and inhibited by cobalt, manganese, silver, stannous and zinc ions as well as EDTA. Cadmium, copper, and ferric ions block hair digestion. The keratinase is rather stable in buffer solutions of pH 4 to 10.