Formation of melanin-tyrosinase complex and its possible significance as a model for control of melanin synthesis.

Previous reports have shown that the tyrosinase activities of melanosomes and soluble tyrosinase isolated from melanoma were diminished when these preparations were incubated with 3,4-dihydroxyphenylalanine (dopa). It was concluded from these results that the tyrosinase activities of these preparations decreased when melanin was synthesized in these systems. The present investigation has revealed that melanin synthesized in vitro from dopa formed a complex with purified mushroom tyrosinase. The addition of melanin diminished the tyrosinase activity of the sample. These results show that the formation of the melanin-tyrosinase complex results in a decrease in the activity of the tyrosinase solution. The tyrosinase activity of the melanin-tyrosinase complex could not be increased by certain procedures which were previously found to enhance the tyrosinase activity of isolated melanosomes.