Influence of Organic Salts on the Action of Tyrosinase

Abstract

With the object of finding an analogy to the inhibition phenomena observed by us in precipitin reactions with azoproteins 1 we examined the effect of the sodium salts of organic acids on the action of the oxidase of potatoes and mushrooms on tyrosin. Many were found to have an inhibiting effect upon the ferment action, but the

degree of inhibition varied greatly with the different acids. In a general way it can be stated that the carboxylic acids of benzene and of other cyclic compounds acted more strongly than fatty acids, and that stronger inhibition was caused by the meta and para substituted acids than by the ortho substituted. The tests were made with solutions neutral to litmus, and also in the presence of buffers. Most of the substances acted similarly on mushroom extract and on potato extract, but in some instances differences were observed.

A part of the results is presented in Table I, the figures indicating the degree of oxidation as judged from the intensity of the color.

Somewhat analogous phenomena were noticed when in place of ferment, iron salts and H₂O₂ were used for the oxidation of tyrosin.

A similar difference in the action of ortho, meta and para substituted aromatic acids was also seen in their inhibiting effect upon the color reaction of sodiumsalicylate with ferric chloride. Apparently this was due to the formation of iron compounds which separated in the form of precipitates, but the effect was the same when the precipitation was prevented by addition of a solution of gelatin.

This is a preliminary report.