2-5-Diketogluconate

Biddle and Wehry [429] carried out fluorometric determination of manganese II in seawater via catalysed enzymic oxidation of 2,3-diketogluconate. The detection limit was 8 pmoll-1 Mn (II). 

Corynebacterium diketogluconate reductase [38] MVDP, murine vas deferens protein [35],... 

Ascorbate (AH-) can make two e available, and consequently both AH- and its one e oxidation product, the ascorbyl radical (A -), become antioxidants. The latter dismutates to form A - and dehydroascorbicadd (A), as shown in Scheme 3, or is reduced back by GSH or GSH-dependent enzymes (glutaredoxine, thioredoxin). Immediately, A is irreversibly hydrolized to 2,3-diketogluconic acid and then to oxalate, thre-onate, and many other metabolites. This last point is important because products derived from the hydrolysis of A may potentially damage proteins by glycation (47). 

Diacetone sorbose to diketogluconic acid C Hoffmann-LaRoche Seiler and Robertson (1982)... 

Vitamin C Vitamin C activity resides in two naturally occurring compounds ascorbic acid and its oxidation product, dehydroascorbic acid. In human tissues ascorbic acid predominates. Ascorbic acid is labile in most samples, oxidizing to dehydroascorbic acid and then degrading to 2,3-diketogluconic acid. Various reagents can be used to prevent this oxidation in plasma or whole blood samples. Extraction with 5% metaphosphoric or trichloroacetic acid is the usual initial preparation. Only ascorbic acid may be detected by UV spectrophotometry at 245-265 nm, the absorption maxima of dehydroascorbic acid being 210 nm. A similar problem exists with electrochemical detection where ascorbic acid oxidizes at +0.7V with carbon electrodes. Fluorescent derivatives may be formed with 2-4-din-itrophenylhydrazine or o-phenyldiamine. These derivatives can be assayed by reversed-phase HPLC. 

The nature of the products formed under various conditions and the mechanism of the reaction have been investigated by Kiichlin 252). At low temperatures and for dilute solutions in the presence of ferrous sulfate, the following products were formed from glucose and identified as derivatives glucosone, 2-ketogluconic acid, and 2,3-diketogluconic acid in concentrated solutions, formaldehyde also was found. The formation of these products at low temperatures was ascribed to the following series of reactions ... 

Doner LW, Hicks KB. High-performance liquid chromatographic separation of ascorbic acid, erythorbic acid, dehydroascorbic acid, dehydroerythorbic acid, dike-togulonic acid, and diketogluconic acid. Anal Biochem 1981 115(1) 225—30. 

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