Über die dehydrierende Autoxydation und die biologischen Oxydationen.

Abstract

When a ferrous salt was added to an aq. ascorbic acid soln., the resulting violet color was due to oxygen action; an oxide of a primary ferrous-ascorbic acid compound having been formed. Addition of Na dithionite reduced this to its formerly colorless condition. Shaking with air restored the violet color. Of the many substances, only the following 3 gave it with equal intensity: ascorbic acid, catechol, dioxy-maleic acid. Cystein, oxal-acetic acid, salicylic acid, and acetyl-aceton reacted but much less intensively. The ferrous-iron catechol system was studied in an attempt to analyse the oxidation system. On oxidation by air, this formed ferric-complexes which were red in alkaline soln., violet in neutral, and green in faintly acid solns. Numerous Fe-catechol molecules were studied. Catechol united at once with ferrous Fe, which is quickly oxidized by air to the ferric condition. Since ferrous compounds are oxidized slowly, the union of ferrous Fe with catechol leads to an auto-oxidation or acceleration. The oxidation was not due to ferric ions since the solns. contained none. Carbon monoxide strongly inhibited the auto-oxidation. Tests were made on a long series of organic compounds, mainly alcs. and acids[long dash]which form Cu complexes and also inhibit de-hydrogenases, to determine whether the two capacities were correlated. The enzymes were: succino-dehydro-genase from pigeon pectoral muscle; catechol-oxidase from potato which is a known Cu-protein; and poly-phenoloxidase from potato. In general, substances that do not form Cu complexes do not inhibit the foregoing 3 enzymes, strong inhibition was associated with Cu complex formation.