CHARACTERIZATION OF HUMAN HAIRBULB TYROSINASE - PROPERTIES OF NORMAL AND ALBINO ENZYME

Human hairbulb tyrosinase from normally pigmented and tyrosinase-positive oculocutaneous albino (TPA) hairbulbs was studied by single hairbulb and by pooled hairbulb assay procedures. The response to temperature and pH was the same for TPA and normal enzyme. The K(m) for tyrosine as substrate and the K(m) or dopa as cofactor was the same for TPA and normal enzyme. These studies show that TPA tyrosinase is kinetically normal and that the defect with this form of albinism must be elsewhere in the melanin pathway.