CHARACTERIZATION OF STRUCTURAL-PROPERTIES FOR MORPHOLOGIC DIFFERENTIATION OF MELANOSOMES .3. FREE AND PROTEIN-BOUND DOPA AND 5-S-CYSTEINYLDOPA IN B-16 AND HARDING-PASSEY MELANOMAS

[摘要] The free and protein-bound forms of dopa, 5-S-cysteinyldopa (5-S-CD), and 5-S-glutathionedopa (5-S-GD) in B16 and Harding-Passey (HP) mouse melanomas was studied to determine the role of these catechols for melanogenesis and melanosome morphogenesis. These tumors produce melanosomes different in color and ultrastructure, i.e., eumelanosome type in B16 and pheomelanosome type in HP. Between B16 and HP mouse melanomas, no significant difference in the level of free dopa and 5-S-CD in melanosomes and tumors was found although the levels of these catechols reflected well the type of melanogenesis in control hair of normal mice. A significant difference in free 5-S-GD level, which might reflect the observed difference in melanogenesis was observed. No difference in the level of bound dopa and 5-S-CD in either melanosomes or tumors was detected. The striking difference in the color of melanosomes between B16 and HP melanomas seems to be related primarily to the contents not the types of melanin pigments.