Isotope effects in the tyrosinase catalysed hydroxylation of l-tyrosine methyl derivatives.

To investigate isotope effects in the hydroxylation of [3',5'-2 H2 ]-α-methyl- and [3',5'-2 H2 ]-N-methyl-l-tyrosine, they were synthesised using acid catalysed isotope exchange at high temperature. The kinetic and solvent deuterium isotope effects on Vmax and Vmax /Km parameters of tyrosinase in its action on methylated derivatives of l-tyrosine were determined using the non-competitive spectrophotometric method. Lineweaver-Burk plots were used to consider the inhibition type of O-methyl-l-tyrosine, revealing that it is an uncompetitive inhibitor of tyrosinase.