Enzymic Studies on TPN L-Hexonate Dehydrogenase from Rat Liver

Abstract

Little has been known about the reduction of uronic acid to the corresponding aldonic acid. A few examples have been presented of the reduction of hexuronic acids, viz. the reduction of D-glucuronic acid or its lactone by TPNH* (1-4) and that of some keturonic acids by DPNH (5-8). On the other hand, it has been established by several workers that the immediate TPN L-Hexonate Dehydrogenase 619 aldehyde reductase proposed recently by Hers (4) or glucuronate reductase (26). A part of this paper was reported previously (25, 27). METHODS AND MATERIALS Materials•\D-Glucurono-r-lactone, sodium D-glu curonate, ethyl D-glucuronate, and D-glucuronamide were obtained from the Chugai Pharmaceutical Com pany. D-Galacturonate was purchased from the Nutritional Biochemicals Corporation, D-mannurono-ƒÁ-lactone was provided through the courtesy of Dr .

Metabolic alterations in the human erythrocyte produced by increases in glucose concentration

“…Krebs and Veech (27) The reduced (free NAD)/(free NADH) ratio in erythrocytes incubated with 50 mm glucose probably results from increased sorbitol oxidation to fructose by the NAD linked sorbitol dehydrogenase. This speculation is supported by the observation that barbital, which inhibits sorbitol synthesis by aldose reductase " or L-gulonate: NADP oxidoreductase (29), reduced the lactate:pyruvate ratio. Under these circumstances there was a significant reduction in the levels of total triose-phosphaate.…”

Developmental expression and function of aldehyde reductase in proximal tubules of the kidney

“…Aldehyde reductase participation in the pathways of inositol catabolism and vitamin C synthesis was suggested based on its substrate specificity for glucuronate (20,26). To check whether aldehyde reductase participates in these pathways in vivo, we administered the aldehyde reductase inhibitor AL-1576 at 20 mg⅐kg Ϫ1 ⅐day Ϫ1 orally to mice for 4 days and measured urinary concentrations of glucuronate and vitamin C. Measurements were normalized by creatinine for correction of urinary dilution.…”

“…The combination of two transcription factors, STAF and Sp1 family factors, both of which are consistent with ubiquitous expression, drives basal expression of the aldehyde reductase gene (9). However, multitissue RNA analysis in mice and humans and analysis of enzyme activity in various rat and murine tissues show that the level of aldehyde reductase is significantly higher in the kidney than in other organs (3,7,20). This implies a special role for aldehyde reductase in the kidney in addition to the general metabolic role it plays in all organs and possibly during embryonic development (3).…”

The Aldo-Keto Reductase Superfamily and its Role in Drug Metabolism and Detoxification

“…One of the first AKRs to be discovered, ARK1A1 was identified as a key enzyme involved in ascorbic acid biosynthesis (Mano et al, 1961). It is a cytosolic, NADPH-dependent, monomeric oxidoreductase with a compulsory ordered substrate binding and product release.…”