[Isoenzymes of melanosomal tyrosinase isolated from transplanted hamster melanomas].

The isoenzyme profiles of tyrosinase isolated from melanosomal and cytoplasmic fractions of hamster melanoma were investigated. The liberation of the enzyme from the melanosomal membranes was achieved by their treatment with Triton X-100 or alpha-chymotrypsin. The isoenzyme spectrum of tyrosinase liberated by use of Triton X-100 from melanosomes differing in the degree of melanization is identical to that of the cytoplasmic enzyme and gives three peaks on a densitogram. The liberation of melanosomal tyrosinase by alpha-chymotrypsin results in the appearance of an additional isoenzyme due to proteolytic degradation. The role of tyrosinase isoenzymes in the synthesis of melanin is discussed.