Tyrosinase activity in a highly pigmented human melanoma and in negro skin.

Abstract

SummaryThe comparison of the tyrosinase present in the skin of a 38-year-old male Negro with that present in highly pigmented metastatic melanoma in the same individual revealed a number of differences. In the skin, enzymic activity varied with the skin region, showed low specific activity, was confined to the particulate fraction, and showed 12-25% tyrosine carboxylgroup incorporation into melanin. Melanoma tyrosinase activity was similar in the various metastases, showed high specific activity, was present in both the particulate and soluble fractions, and showed only 9.4-9.8% tyrosine carboxyl-group incorporation into melanin. Three tyrosinase isozymes were present in the melanomas. Prolonged storage at −27° of the melanomas increased tyrosinase activity 2-6-fold. Enzymic inhibitors may have a role in the control of tyrosinase activity in melanoma.