The Enzymatic Oxidation of Ascorbic Acid in the Slime Mold, Physarum Polycephalum.

Abstract

An atypical ensymatic oxidation of ascorbic acid is present in the supernatant from a high speed (20,000 x g) centrifugation of homogenates of P. polycephalum. The enzyme is resistant to cyanide, azide, sulfide and carbon monoxide as well as metal chelators and -SH enzyme inhibitors. The oxidation of ascorbic acid is stimulated by catalytic amounts of diethyldithiocarbamate (DDC) and tetraethylthiuram disulfide (TTD). Indirect evidence indicates the formation of H2O2 as an end product of this oxidation. Dialysis markedly inactivates the ascorbic acid oxidizing ability of the enzyme. The addition of DDC or concentrated dialysate results in the restoration of activity. The possibility of DDC and TTD acting as model substances for a natural unknown carrier is discussed.