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Characterization of enterobacteria by starch-gel electrophoresis of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase.

Specific activities and electrophoretic mobilities of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase were determined in 38 isolates of the family Enterobacteriaceae and in 10 isolates of the related Pasteurella. The deficiency of glucose-6-phosphate dehydrogenase in P. pestis was verified. Enzymes obtained from different strains of the same species exhibited an unexpected degree of heterogeneity. For example, 8 and 11 apparent variants of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase, respectively, were found in 14 strains of Escherichia coli. Although similar frequencies of heterogeneity were noted in 7 strains of P. pseudotuberculosis, 5 species of Shigella, and 8 species of Salmonella, differences in mobility were generally small in comparison with those observed between strains of E. coli. Values obtained for the pasteurellae, shigellae, and salmonellae, thus fell within narrow ranges that may prove typical for the genera. However, most of these ranges, as well as many values observed for single species of other genera, were overlapped by the wide range recorded for E. coli. The significance of this observation was discussed with respect to the relative age and taxonomic position of the organisms in question. The method could be used to distinguish between most wild-type strains of the same species and should thus facilitate investigations of genetic transfer and epidemiology.

Electrophoresis↗

Activity of some enzymes of carbohydrate metabolism in human subcutaneous adipose tissue in newborns, infants and adults. I. Activity of pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase.

The activity of glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, pyruvate kinase (PK) and lactate dehydrogenase (LDH) was measured in human adipose tissue (AT) of newborns aged 0-2 and 2-48 h, of 3- to 5-month-old infants and of adults. AT was sampled by means of a special needle from the gluteal region without anesthesia. We observed significantly higher activity of the two pentose phosphate shunt enzymes when calculated on protein content and wet weight basis in newborns as compared to infants and adults. There were no differences for PK and LDH between newborns and adults when the values were calculated for the soluble protein. The protein concentration of the AT decreased significantly during the development.

Adipose Tissue↗

Gender-linked differences in dietary induction of hepatic glucose-6 phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and malic enzyme in the rat.

The objective of these studies was to determine how alterations in dietary carbohydrate affect hepatic glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and malic enzyme (ME) activities in adult female rats. Rats were either starved 2 d and then refed a nonpurified diet or a purified 65% carbohydrate diet (glucose, sucrose, fructose or cornstarch) for 3 d, or switched from nonpurified to purified diets for 3 d. Liver G6PDH, 6PGDH and ME activities were determined. In males, enzyme activities were 8- to 12-fold and 3-fold higher when starved and refed purified diets and nonpurified diets, respectively, whereas in females, activities were 2- to 3-fold higher only when refed purified diets. Both genders had higher enzyme activities when shifted to purified diets. Females responded less dramatically than males. Of the higher enzyme activities observed during starvation-refeeding studies, in females 58-65% of the change is a function of switching rats from nonpurified to purified diets. In contrast, in males only 24-40% of the higher activities could be attributed to diet shifting. Results of these studies indicate that the effects of dietary carbohydrates on hepatic G6PDH, 6PGDH and ME activities are gender dependent.

Animals↗

Dietary induction of hepatic glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malic enzyme in lean and obese female Zucker rats.

Responses of the hepatic lipogenic enzymes, glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and malic enzyme (ME) to starvation refeeding and diet shifting were determined in lean and obese female Zucker rats. Rats were either fed nonpurified diet, starved 48 hr, and then refed nonpurified diet or one of the refined carbohydrate diets containing either glucose, fructose, cornstarch, or sucrose for 72 hr, or shifted from nonpurified diet directly to one of the refined carbohydrate diets for 72 hr. Initial activities were greater in obese than lean rats for all three enzymes studied. Similar to other strains of female rats, lean Zucker rats failed to demonstrate a starve-refeed response when refed nonpurified diet. Obese female littermates showed a statistically significant increase in enzymes when refed a nonpurified diet. Both lean and obese female Zucker rats demonstrated increases in enzyme activities above controls when starved and refed any of the refined carbohydrate diets. The greatest responses were observed when female rats were starved and refed sucrose; activities increased 2.6- to 3.5-fold in lean and 3.0- to 4.3-fold in obese Zuckers. In lean females 50-70% of the starve-refeed response observed with G6PDH and ME can be accounted for by simply shifting from a nonpurified diet to the respective refined carbohydrate diet, whereas in obese females only 33-55% of the increase could be attributed to diet shifting. Plasma testosterone/estrogen ratios were consistently 1.5 times higher in obese than in lean female rats. This phenotypic difference may potentiate the heightened starve-refeed overshoot response observed in obese rats.

Animals↗

In situ kinetic parameters of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase in different areas of the rat liver acinus.

The reaction velocity of glucose-6-phosphate dehydrogenase (G6PDH) and phosphogluconate dehydrogenase (PGDH) was quantified with a cytophotometer by continuous monitoring of the reaction product as it was formed in liver cryostat sections from normal, young mature female rats at 37 degrees C. Control incubations were performed in media lacking both substrate and coenzyme for G6PDH activity and lacking substrate for PGDH activity. All reaction rates were non-linear but test minus control reactions showed linearity with incubation time up to 5 min using Nitro BT as final electron acceptor. End point measurements after incubation for 5 min at 37 degrees C revealed that the highest specific activity of G6PDH was present in the intermediate area (Vmax = 7.79 +/- 1.76 mumol H2 cm-3 min-1) and of PGDH in the pericentral and intermediate areas (Vmax = 17.19 +/- 1.73 mumol H2 cm-3 min-1). In periportal and pericentral areas, Vmax values for G6PDH activity were 4.48 +/- 1.03 mumol H2 cm-3 min-1) and 3.47 +/- 0.78 mumol H2 cm-3 min-1), respectively. PGDH activity in periportal areas showed a Vmax of 10.84 +/- 0.33 mumol H2 cm3 min-1. Variation of the substrate concentration for G6PDH activity yielded similar KM values of 0.17 +/- 0.07 mM, 0.15 +/- 0.13 mM and 0.22 +/- 0.11 mM in periportal, pericentral and intermediate areas, respectively. KM values of 0.87 +/- 0.12 mM in periportal and of 1.36 +/- 0.10 mM in pericentral and intermediate areas were found for PGDH activity. The significant difference between KM values for PGDH in areas within the acinus support the hypothesis that PGDH is present in the cytoplasmic matrix and in the microsomes. A discrepancy existed between KM and Vmax values determined in cytochemical assays using cryostat sections and values calculated from biochemical assays using diluted homogenates. In cytochemical assays, the natural microenvironment for enzymes is kept for the demonstration of their activity and thus may give more accurate information on enzyme reactions as they take place in vivo.

Animals↗

Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activities in early stages of development in dystrophic chickens.

Glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activities were assayed in superficial pectoral muscles of hereditary dystrophic chickens, 1 week, 2 weeks, 4 weeks and 4 months after hatching. In control chickens, activities of G6PDH and 6PGDH were very low at 4 months of age; however, at 1 week of age, they were much higher than those at 4 months of age. Activities of G6PDH and 6PGDH were significantly higher in dystrophic chickens compared with those in the controls at all the stages of development studied. These findings suggest that considerable activities of G6PDH and 6PGDH are present within the pectoral muscle cells at early stages of development, at least in dystrophic chickens. GAPDH activity was significantly lower in dystrophic chickens at 2 weeks, 4 weeks and 4 months of age compared with those in control chicken. These findings together with our previous studies (Mizuno 1984a,b) in which increased activities of superoxide dismutases, catalase, glutathione peroxidase and glutathione reductase were reported in dystrophic chickens, indicate the presence of an increased capacity for the turnover of oxygen-free radicals within muscle cells in dystrophic chickens, and that oxygen-free radicals and the related activated oxygen species may be playing a role in inducing cellular damage.

Age Factors↗

Simultaneous automated determination of glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in whole blood.

We report a potentiometric fully automated method for determining red cell glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase activities and the glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index using 25 microliters of whole blood. No sample pre-treatment (e.g., preparation of the haemolysate) is needed and the measurements are performed at pH 8.0 and 37 degrees C under the conditions recommended by the ICSH committee. The reproducibility was constantly good, with within-run CV of 1.0% (glucose 6-phosphate dehydrogenase) and 5.9% (glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase) for activities in glucose 6-phosphate dehydrogenase non-deficient adults, and of 2.3% (glucose 6-phosphate dehydrogenase, G6PD) and 2.5% (glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase) for G6PDMediterranean heterozygotes. Linearity was observed up to an activity of 2800 U/l of glucose 6-phosphate dehydrogenase. Results of glucose 6-phosphate dehydrogenase activity (U/l) in whole blood (y) correlated well with those obtained with the previously described monostarter assay, performed at pH 9.2 (y = 0.60x + 37; n = 80; r = 0.991). Results of 6-phosphogluconate dehydrogenase (U/l) in whole blood (y) correlated well with those obtained by the ICSH recommended method (x) (y = 0.779x - 44; n = 23; r = 0.991). Reference intervals are reported for glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index relatively to normal, beta- and alpha-thalassaemic glucose 6-phosphate dehydrogenase non-deficient adults, to glucose 6-phosphate dehydrogenase deficient adult males and to G6PDMediterranean non-thalassaemic heterozygotes. We demonstrate that the diagnostic sensitivity of the glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index in detecting the G6PDMediterranean heterozygotes is superior to that of the glucose 6-phosphate dehydrogenase activity alone.

Adolescent↗

Sex differences in the control of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Interaction of estrogen, testosterone and insulin in the regulation of enzyme levels in vivo and in cultured hepatocytes.

Control of the activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malate dehydrogenase was investigated in intact rats and in hepatocyte cultures. 1) Adult females had 2-fold greater activities of hepatic glucose-6-phosphate- and 6-phosphogluconate dehydrogenases than adult males, but similar activities of malate dehydrogenase. Castrated males showed decreased activities of all three enzymes in comparison to age- and weight-matched intact controls. In starved animals the activities of all three enzymes decreased significantly. After refeeding with nonpurified diet the activities returned to the prestarved levels in females, but increased to clearly higher values in intact and castrated males. 2) Estrogen levels were in the same range in immature and adult male and female rats. Testosterone levels were highest in adult males, clearly lower in adult females (1/8) and immature males (1/8), still lower in immature females (1/15) and lowest in castrated males (1/40). A simple correlation of the sex differences in these hormone levels to sex differences in glucose-6-phosphate- and 6-phosphogluconate dehydrogenase activities was not apparent. 3) In serum-free, dexamethasone-supplemented 48-h cultures of hepatocytes from both male and female rats the basal activities of glucose-6-phosphate dehydrogenase were the same; they were increased 2-3 fold by insulin alone, 1.5 fold by estrogen alone and 4-5 fold by insulin plus estrogen. Apparently sex differences did not persist in 48-h cell cultures. 4) In 48-h cultures of male hepatocytes, then used as the experimental model, insulin alone increased the activity not only of glucose-6-phosphate dehydrogenase but also of 6-phosphogluconate and malate dehydrogenases.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗