Tyrosinase activities of cell-free extracts and living cells of cultured melanoma cells

摘要: Abstract Melanogenesis in the course of monolayer culture a stably melanotic clonal line C 2 M, derived from mouse melanoma B 16, was investigated. Tyrosinase activity per cell cell-free extracts highest when extract prepared cells mid-exponential phase growth, it more than 6 times that fully grown or very early phase. On other hand, enzyme living and decreased rapidly to level less one tenth maximum activity, stationary The upper limit population density cultured permissive for melanin synthesis (2 3 × 10 5 cells/cm ) much higher normal (nonneoplastic) melanocytes, which had been reported produce only under conditions growth. relative efficiency tyrosinase situ , expressed by ratio extract, exponential This decrease correlates culture, little if at all division rate, suggests suppressing mechanism working level.