Interaction of methotrexate with melanins and melanosomes from B16 melanoma.
It has been demonstrated that methotrexate forms stable complexes with melanin and melanosomes isolated from B16 melanoma. The number of binding sites and binding constants for methotrexate binding by intact melanosomes and melanin were n = 0.046 mumol/mg, K = 0.32 x 10(4) M-1 and n = 0.063 mumol/mg, K = 1.08 x 10(4) M-1, respectively. Binding of methotrexate to synthetic DOPA-melanin used for comparison also shows a single class of binding sites, n = 0.060 mumol/mg with binding constant K = 2.34 x 10(4) M-1. The possibility of side effects caused by methotrexate-melanin interactions after treatment of neoplasms is discussed.
Wilczok
T
T
Department of Biochemistry and Biophysics, Silesian Medical Academy, Katowice, Poland.
Stepień
K
K
Buszman
E
E
Porebska-Budny
M
M
D000818:Animals; D001665:Binding Sites; D004295:Dihydroxyphenylalanine / Q000032:analysis; D006868:Hydrolysis; D007700:Kinetics; D008543:Melanins / Q000378:metabolism*; D008544:Melanocytes / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000378:metabolism*; D008727:Methotrexate / Q000032:analysis / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL
D008543:Melanins; D004295:Dihydroxyphenylalanine; D008727:Methotrexate