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Tritium effect in peroxidation of ehtanol by liver catalase.

ABSTRACT: 1. Simultaneous determination of the rate of appearance of 3H in water from [(1R)-1-3H1] ethanol and the rate of acetaldehyde formation in the presence of rat or ox liver catalase under conditions of steady-state generation of H2O2 allowed calculation of the 3H isotope effect. The mean value of 2.52 obtained for rat liver catalase at 37 degrees C and pH 6.3-7.7 was independent of both ethanol concentration and the rate of H2O2 generation over a wide range. At 25 degrees C a slightly lower mean value of 2.40 was obtained with the ox liver catalase. 2. Neither the product, acetaldehyde, nor 4-methylpyrazole influenced the two rates measured in the assay. 3. Relating the value obtained for the 3H isotope effect to a known value for the 2H isotope effect strongly supports the view that both values are close to the true isotope effect with the respective substituted compounds on the rate constant in the catalytic step involving scission of the C-H bond. 4. The constancy of the isotope effect under various conditions makes it possible to use it for interpretations in vivo. 5. It was established that beta-D-galactose dehydrogenase exhibits B-specificity towards the nicotinamide ring in NAD.

SUBMITTER: Damgaard SE

PROVIDER: S-EPMC1183624 | biostudies-other | 1977 Oct

REPOSITORIES: biostudies-other

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Project description:BackgroundOxidative Stress, an imbalance in the pro-oxidant/antioxidant homeostasis, occurs in many physiological and non-physiological processes and several human diseases, including diabetes mellitus (DM) and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Since the incidence of G6PD deficiency in Jordan and many parts of the world is high, this study aimed to measure the effect of G6PD deficiency on the oxidative markers and the antioxidant glutathione (GSH) in diabetic and non-diabetic individuals.MethodsWhole blood G6PD deficiency was screened by the fluorescent spot method, and erythrocyte G6PD activity was determined using a quantitative assay. Since protein carbonyl (PC) and malondialdehyde (MDA) are the most widely measured markers for protein and lipid oxidation, respectively, plasma PC and MDA, in addition to blood GSH were determined by spectrophotometric assays, as biomarkers of oxidative stress.ResultsThe incidence of G6PD deficiency among the diabetic subjects was 15%. PC level in patients with diabetes and in G6PD-deficient subjects was 5.5 to 6-fold higher than in non-diabetic subjects with sufficient G6PD levels (p<0.001). This fold increase was doubled in diabetic patients with G6PD deficiency (p<0.001). Furthermore, the MDA level was significantly increased by 28-41% in G6PD-deficient, diabetics with sufficient G6PD, and diabetics with G6PD deficiency compared to MDA level in non-diabetic with sufficient G6PD. On the other hand, GSH was significantly reduced to half in G6PD-deficient subjects and in diabetics with G6PD-deficiency.ConclusionsThe results showed that diabetes and G6PD deficiency increased protein oxidation and lipid peroxidation. However, the combination of both disorders has an additive effect only on protein oxidation. On the other hand, GSH level is only reduced in G6PD deficiency. In addition, diabetes and G6PD deficiency appear to be genetically linked since the incidence of G6PD deficiency among people with diabetes is more than the general population.

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Tritium effect in peroxidation of ehtanol by liver catalase.

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