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Biomedical subjects

S C Gupta

Publications and source records attributed to S C Gupta.

At least 145 records · Page 8Linked to original sources
PubMed1984

Malyl-CoA formation in the NAD-, CoASH-, and alpha-ketoglutarate dehydrogenase-dependent oxidation of 2-keto-4-hydroxyglutarate. Possible coupled role of this reaction with 2-keto-4-hydroxyglutarate aldolase activity in a pyruvate-catalyzed cyclic oxidation of glyoxylate.

The alpha-ketoglutarate dehydrogenase complex of either pig heart or Escherichia coli catalyzes a NAD- and CoASH-dependent oxidation of 2-keto-4-hydroxyglutarate which is stereoselective toward the L-isomer of this hydroxyketo acid. L-Malyl-CoA is the product of the reaction; the evidence includes observing (a) a steady increase in absorbance at 230 nm during the oxidation of 2-keto-4-hydroxyglutarate, (b) a positive response of oxidation reaction mixtures to neutral hydroxylamine, (c) loss of the two foregoing results concomitant with release of thiol-reacting material and the formation of free malate when reaction mixtures are heated, (d) formation of a hydroxamate which has chromatographic mobilities identical to that of chemically synthesized malate hydroxamate, (e) enzymatic formation of a radioactive product from 14C-labeled 2-keto-4-hydroxyglutarate which co-migrates with chemically synthesized malyl-CoA, and (f) hydrolysis of the product by citrate synthase, an enzyme absolutely specific for citryl-CoA and L-malyl-CoA. A 1:1:1 stoichiometric relationship exists between the amount of 2-keto-4-hydroxyglutarate oxidized, NAD reduced, and malate (or malyl-CoA) formed. Results from studies in which either 14C-labeled 2-keto-4-hydroxyglutarate, pyruvate, or glyoxylate is incubated with mixtures of purified enzymes or extracts of E. coli support the suggestion that the aldolase which preferentially catalyzes formation of L-2-keto-4-hydroxyglutarate from pyruvate plus glyoxylate in E. coli is coupled with the oxidative decarboxylation of this substrate, as reported here, and other enzymes in a multistep pyruvate-catalyzed cyclic oxidation of glyoxylate.

Acyl Coenzyme A↗
PubMed1984

Synthesis and degradation of nitrite reductase in pea leaves.

We have shown in a previous publication (Gupta, Beevers 1983 J Exp Bot 34: 1455-1462) that the level of extractable nitrite reductase activity in pea (Pisum sativum cv Burpeeana) leaves is subject to environmental perturbations. In the current study, we have used rocket immunoelectrophoresis to quantitate the level of nitrite reductase protein in extracts from pea plants subjected to various environmental treatments. The level of nitrite reductase cross-reacting material closely followed the level of assayable nitrite reductase activity. The environmental conditions which enhanced the level of extractable nitrite reductase activity resulted in an increased level of nitrite reductase cross-reacting material in the extracts. In contrast, environmental conditions which resulted in a decrease in the level of extractable nitrite reductase activity produced a decline in cross-reacting material. These results indicate that the environmentally induced modulation of extractable nitrite reductase activity involves alteration of enzyme level and is not mediated by a reversible activation-inactivation of the existing enzyme.

Journal Article↗
PubMed1984

Peroneal tubercle and its variations in the Indian calcanei.

A total number of 1,410 calcanei of either sex belonging to people of Agra and Lucknow region were studied and classified into 4 types depending upon the pattern of peroneal tubercle. A significant difference in the incidence of various types in the two regions were observed.

Adult↗
PubMed1984

A study of blood ascorbic acid in leprosy.

The basal level of blood ascorbic acid was studied in 70 cases of polar leprosy. The level was found to be significantly reduced in both polar types, more so in tuberculoid. In untreated cases of these two polar forms, the differences were highly significant. No significant differences were found between untreated and treated cases of either form of leprosy, indicating that dapsone (DDS) has no effect on the ascorbic acid level. In lepromatous leprosy, the level was not affected by erythema nodosum leprosum (ENL). The deficiency of ascorbic acid in leprosy might be due to the disease per se and/or associated with nutritional factors. In trophic ulcers after supplement therapy for 60 days, the low level of ascorbic acid became close to the control group with marked improvement in the healing of the ulcers clinically. In addition, lactic and pyruvic acids were also measured and found to be significantly raised. After ascorbic acid supplement, the levels fell to near the control values, indicating that ascorbic acid played a role in controlling the infection as well as possible thiamine deficiency and also checked the disturbance caused by DDS on lactate and pyruvate metabolism. The present study suggested that supplementing DDS therapy with ascorbic acid might provide a beneficial effect on the general condition of the leprosy patients and the early healing of trophic ulcers.

Ascorbic Acid↗