[Effect of tyrosinase inhibitors on phenol oxidase (EC 1.14.18.1)]

Phenoloxidase is a specific enzyme for defence cells. It has been histochemically investigated, if substances partly known as tyrosinase inhibitors inhibit the phenoloxidase activity too. The tested substances are: thiourea, sodium-hydrogensulfate, cysteine, 2,3-dimercapto-propanol, N,N-dimethyl-p-phenylendiamine, glutathione, and ascorbic acid. It was detected for all substances, except dimethylphenylendiamine, an inhibitory effect. An attack at the enzyme molecule could be demonstrated for thiourea and dimercaptopropanol. The possibility of enzyme inhibition by these sulphur containing substances is of clinical interest.