CHARACTERISTICS OF TYROSINASE IN B-16 MELANOMA

[摘要] Tyrosine hydroxylase, dopa oxidase and peroxidase activities were studied in soluble fractions of B16 melanoma tumor homogenates by polyacrylamide gel disc electrophoresis. Stained gels were scanned photometrically and gel slices were assayed radiometrically. In these preparations, the 2 bands of tyrosine hydroxylating activity were completely separated from the peroxidase activity but coincided with 2 major bands of dopa oxidase activity. The 3rd dopa oxidase band coincided with the single band of peroxidase activity. The soluble fraction of cultured cell homogenates had no peroxidase activity, but the 2 tyrosine hydroxylase bands coincided exactly with the 2 dopa oxidase bands. In the soluble fraction of this mouse melanoma bifunctional tyrosinase exists as 2 electrophoretically separable forms which are independent of peroxidase.