A new type of uncompetitive inhibition of tyrosinase induced by Cl- binding.

A new type of Cl- induced inhibition of mushroom derived tyrosinase has been detected in this study, and it is defined as the reversible partial hyperbolic uncompetitive inhibition. The Cl- binding site was only induced at the state of the enzyme-substrate complex, and this was confirmed with the intrinsic fluorescence changes. As the oxygen bridge is broken by L-DOPA binding, Cl- simultaneously binds to the ES state to form the ESI complex. It is worth noticing that tyrosinase reacts sensitively to Cl- in the manner of a complex interaction, and this indicates that Cl- might be physiologically involved in the regulation of tyrosinase activity.