Role of Ascorbic Acid in Microsomal Electron Transport and the Possible Relationship to Hydroxylation Reactions

In microsomes of pig and beef adrenals, an ascorbic acid-dependent DPNH* oxidase has been demonstrated (Kersten et aZ.l~~).FIGURE 1 shows the basic experiment: DPNH is not, or only to a very small extent, oxidized by the adrenal microsomes alone; after addition of ascorbic acid, a marked DPNH oxidation can be seen.Principally the same phenomenon-an ascorbic acid-dependent D PNH oxidation-has been demonstrated in rat liver and kidney micro some^.^In * The following abbreviations are used: DPN = diphosphopyridine nucleotide; DPNH = reduced diphosphopyridine nucleotide; TPN = triphosphopyridine nucleotide; TPNH = reduced triphosphopyridine nucleotide.195 Cytochrome bg itself is autoxidable.* we are indebted to R. Dawson,