Abstract
Because of the structural similarity of L-mimosine to L-tyrosine and L-dopa and its tendency to chelate cupric ion, the influence of this compound on mammalian tyrosinase from mouse melanoma and dopamine β-hydroxylase extracted from bovine adrenal medulla was investigated in vitro. L-Mimosine inhibited tyrosinase competitively and reversibly, and the inhibitory effect was decreased by ferric, aluminum, or cupric ion. Dopamine β-hydroxylase was inhibited by L-mimosine, mimosinamine, and mimosinic acid, but the inhibition was uncompetitive. The results suggest that these enzymes are inhibited by different mechanisms: L-mimosine inhibits tyrosinase because of its structural similarity to the substrate, L-dopa. Dopamine β-hydroxylase is inhibited by L-mimosine, mimosinamine, and mimosinic acid because of their chelate-forming ability.
ACKNOWLEDGMENTS The authors express their deep thanks to Dr. T. Ohuchi for his helpful advice, and Miss K. Ueda for her technical assistance in the enzyme assays.
- Copyright © 1977 by Academic Press, Inc.
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