The Enzymes of Washed Zymin and Dried Yeast (Lebedeff). III. Peroxydase, Catalase, Invertase and Maltase

Abstract

PEROXYDASE. On the assumption that hydrogen peroxide and peroxydase might possibly be capable of oxidising some degradation product of sugar, Bach [1906] submitted sugar to the simultaneous action of hydrogen peroxide, peroxydase and an enzyme capable of decomposing sugar. He chose for his experiments the fermenting enzyme of yeast and employed zymin. Being however of the opinion that yeast contains no peroxydase he made use in his investigations of a peroxydase prepared from horseradish. Although unable to observe any of the oxidation processes the probability of which he had anticipated, he found that when the peroxydase used was previously boiled the amount of carbon dioxide evolved was invariably more than when it was not boiled. This led him to conclude that the presence of active peroxydase had a deterrent effect on the fermenting power of zymin. The authors find 'that fresh English brewery yeast contains active peroxydase. When however the yeast is dried for 17 hours at a temperature of 37' it no longer gives the reaction. On washing the dried yeast however the presence of peroxydase can again be detected. Dried Munich yeast (Schroder) behaves like dried English yeast and does not react for peroxydase when unwashed, but regains that activity on being washed. Whether the peroxydase in yeast has a deterrent effect on the fermentation the authors are at present not prepared to say. It is to be observed that Bach in his experiments used a peroxydase from an outside source (horse-radish) and the presence of an agent in that preparation that would have a retarding effect on fermentation and which could be destroyed by boiling is not impossible. Bioch. viii 15