Abstract
The kinetics of the activation of catechol by tyrosinase prepared from the potato and the mushroom, and of its inhibition by Na m-hydroxybenzoate, were studied. The enzyme-substrate dissociation constants differed markedly between the 2 enzyme sources (Ks potato = 5m[image], Ks mushroom = 0.28m[image]), as did also the enzyme-inhibitor dissociation constants (Ki potato = 2.5m[image], Ki mushroom = 0.6m[image]). For both enzyme prepns. Na m-hydroxybenzoate met the requirements of a competitive inhibitor.