Ak. Chakraborty et Dp. Chakraborty, THE EFFECT OF TRYPTOPHAN ON DOPA-OXIDATION BY MELANOSOMAL TYROSINASE, International Journal of Biochemistry, 25(9), 1993, pp. 1277-1280
1. Tryptophan has been shown to inhibit dopa-oxidation by melanosomal
tyrosinase. 2. The inhibition is of mixed-type with K(i) = 1.6 x 10(-3
) m. 3. Tryptophan does not interact with the oxidation product of the
dopa-oxidase reaction. 4. Neither oxygen nor hydroxyl radicals are in
volved in the inhibition found in presence of tryptophan. 5. Tryptopha
n, like dopa, also inhibits tyrosine hydroxylase and dopa-oxidase acti
vity of melanosomal tyrosinase and its inhibitory mechanism differs fr
om inhibition due to non-substrate type compounds like cysteine, ascor
bic acid. 6. These experiments together with previous findings suggest
that the status of tryptophan may be similar to that of dopa in relat
ion to regulation of melanogenesis.