Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The overall metabolic changes in lactating mammary gland in alloxan-diabetic and anti-insulin-serum-treated rats were assessed by measurement of the incorporation of (14)C from specifically labelled glucose, pyruvate and acetate into carbon dioxide and lipid, together with measurements of enzymes concerned with the pentose phosphate pathway and with citrate metabolism. 2. Alloxan-diabetes depressed the rate of formation of (14)CO(2) from [1-(14)C]glucose and [2-(14)C]glucose to approx. 10% of the control rate; this was partially reversed by addition of insulin in vitro. The quotient Oxidation of [1-(14)C]glucose/Oxidation of [6-(14)C]glucose fell from a value of 17.6 in the control group to 3.9 in the diabetic group and was restored to 14.3 in the presence of insulin in vitro. In keeping with these results it was shown that glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were significantly decreased in alloxan-diabetic rats. 3. Alloxan-diabetes depressed the decarboxylation and the oxidation of labelled pyruvate, but not the oxidation of labelled acetate. 4. The synthesis of lipid from specifically labelled glucose was greatly decreased, that from [2-(14)C]pyruvate was almost unchanged and that from [1-(14)C]acetate alone was increased in alloxandiabetic rats. However, the stimulation of lipid synthesis from acetate by glucose was small in the alloxan-diabetic rats compared with the controls. Insulin in vitro partially reversed all these effects. Both citrate-cleavage enzyme and acetate thiokinase activities were decreased in alloxan-diabetic rats. 5. Treatment of rats with anti-insulin serum depressed the formation of (14)CO(2) from [1-(14)C]glucose and [2-(14)C]glucose, but increased that from [6-(14)C]glucose. This was completely restored by the presence of insulin in vitro. The quotient Oxidation of [1-(14)C]glucose/Oxidation of [6-(14)C]glucose fell from a value of 17.6 in the control group to 3.8 in the anti-insulin-serum-treated group. There were no changes in the activity of glucose 6-phosphate dehydrogenase or 6-phosphogluconate dehydrogenase, but the hexokinase distribution changed and the content of the soluble fraction increased significantly. 6. The synthesis of lipid from specifically labelled glucose was depressed in anti-insulin-serum-treated rats; this effect was completely reversed by addition of insulin in vitro to the tissue slices.
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PMID:Effect of alloxan-diabetes and treatment with anti-insulin serum on pathways of glucose metabolism in lactating rat mammary gland. 569 42

1. Measurements were made of the non-oxidative reactions of the pentose phosphate cycle in liver (transketolase, transaldolase, ribulose 5-phosphate epimerase and ribose 5-phosphate isomerase activities) in a variety of hormonal and nutritional conditions. In addition, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were measured for comparison with the oxidative reactions of the cycle; hexokinase, glucokinase and phosphoglucose isomerase activities were also included. Starvation for 2 days caused significant lowering of activity of all the enzymes of the pentose phosphate cycle based on activity in the whole liver. Re-feeding with a high-carbohydrate diet restored all the enzyme activities to the range of the control values with the exception of that of glucose 6-phosphate dehydrogenase, which showed the well-known ;overshoot' effect. Re-feeding with a high-fat diet also restored the activities of all the enzymes of the pentose phosphate cycle and of hexokinase; glucokinase activity alone remained unchanged. Expressed as units/g. of liver or units/mg. of protein hexokinase, glucose 6-phosphate dehydrogenase, transketolase and pentose phosphate isomerase activities were unchanged by starvation; both 6-phosphogluconate dehydrogenase and ribulose 5-phosphate epimerase activities decreased faster than the liver weight or protein content. 2. Alloxan-diabetes resulted in a decrease of approx. 30-40% in the activities of 6-phosphogluconate dehydrogenase, ribose 5-phosphate isomerase, ribulose 5-phosphate epimerase and transketolase; in contrast with this glucose 6-phosphate dehydrogenase, transaldolase and phosphoglucose isomerase activities were unchanged. Treatment of alloxan-diabetic rats with protamine-zinc-insulin for 3 days caused a very marked increase to above normal levels of activity in all the enzymes of the pentose phosphate pathway except ribulose 5-phosphate epimerase, which was restored to the control value. Hexokinase activity was also raised by this treatment. After 7 days treatment of alloxan-diabetic rats with protamine-zinc-insulin the enzyme activities returned towards the control values. 3. In adrenalectomized rats the two most important changes were the rise in hexokinase activity and the fall in transketolase activity; in addition, ribulose 5-phosphate epimerase activity was also decreased. These effects were reversed by cortisone treatment. In addition, in cortisone-treated adrenalectomized rats glucokinase activity was significantly lower than the control value. 4. In thyroidectomized rats both ribose 5-phosphate isomerase and transketolase activities were decreased; in contrast with this transaldolase activity did not change significantly. Hypophysectomy caused a 50% fall in transketolase activity that was partially reversed by treatment with thyroxine and almost fully reversed by treatment with growth hormone for 8 days. 5. The results are discussed in relation to the hormonal control of the non-oxidative reactions of the pentose phosphate cycle, the marked changes in transketolase activity being particularly outstanding.
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PMID:The pentose phosphate pathway of glucose metabolism. Hormonal and dietary control of the oxidative and non-oxidative reactions of the cycle in liver. 579 34

1. Measurements were made of the activities of enzymes of the pentose phosphate cycle, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, ribose 5-phosphate isomerase, ribulose 5-phosphate epimerase, transketolase and transaldolase, as well as of the related or competing enzymes glucokinase, hexokinase, phosphoglucose isomerase and phosphoglucomutase, in control rats and in rats bearing the growth-hormone- and prolactin-secreting pituitary tumour MtTW5, to study the effect of high endogenous concentrations of growth hormone on this pathway in liver. 2. There was a twofold increase in liver weight. Glucokinase activity/g. of liver decreased to half the control value in the experimental group, although on a total liver basis it remained unchanged. Hexokinase activity increased in parallel with the liver weight, so that the total activity was doubled in rats with a high endogenous concentration of growth hormone. No differences in response were found between heat-stable and heat-labile forms of hexokinase. 3. The activity/g. of liver of the two oxidative enzymes of the pathway decreased slightly in the experimental group, but this was offset by the increase in liver weight, and the resultant effect was a 50% increase in the total activity. 4. Of the non-oxidative enzymes of the cycle the most marked increase on a total liver basis was in ribose 5-phosphate isomerase activity, to 2.5 times the control value. Ribulose 5-phosphate epimerase activity showed the smallest increase. Transketolase and transaldolase activities were also increased. The latter is the rate-limiting enzyme of the non-oxidative reactions of the cycle in these animals. 5. The results are discussed in relation to the glycolytic pathway and synthesis of glycogen, and more particularly to the increased requirement for ribose 5-phosphate for RNA synthesis.
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PMID:The pentose phosphate pathway of glucose metabolism. Influence of a growth-hormone-secreting pituitary tumour on the oxidative and non-oxidative reactions of the cycle in liver. 580 93

1. Measurements were made of the activities of the enzymes of the pentose phosphate pathway concerned in both the oxidative (glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) and the non-oxidative (ribose 5-phosphate isomerase, ribulose 5-phosphate epimerase, transketolase and transaldolase) reactions of this pathway, together with hexokinase and phosphoglucose isomerase, in adipose tissue in a variety of nutritional and hormonal conditions. 2. Starvation for 2 days caused a significant decrease in the activities of all the enzymes of the pentose phosphate pathway, with the exception of glucose 6-phosphate dehydrogenase, when expressed as activity/2 fat-pads; only the activities of ribose 5-phosphate isomerase and ribulose 5-phosphate epimerase were significantly decreased on the basis of activity/mg. of protein. Re-feeding with a high-carbohydrate or high-fat diet for 3 days restored the activity of all the enzymes of the pentose phosphate pathway to the range of the control values, with the exception of transketolase, which showed a marked ;overshoot' in rats re-fed with carbohydrate. Starvation for 3 days caused a marked decrease in the activities of glucose 6-phosphate dehydrogenase and transketolase. 3. On the basis of activity/two fat-pads, alloxan-diabetes caused a marked decrease, to about half the control value, in the activities of all the enzymes concerned in the pentose phosphate pathway, transketolase showing the smallest decrease; hexokinase and phosphoglucose isomerase activities were also decreased. Treatment with insulin for 3 and 7 days raised the activities to normal or supranormal values, transketolase showing the most marked ;overshoot' effect. On the basis of activity/mg. of protein the activity of none of the enzymes was significantly decreased in alloxan-diabetes; transketolase and transaldolase activities were raised above the control values. With insulin treatment for 3 or 7 days the activities of all the enzymes were significantly increased, except that of ribulose 5-phosphate epimerase at the shorter time-interval. Glucagon treatment did not alter any of the enzyme activities expressed on either basis. 4. Thyroidectomy caused a decrease of 30-40% in the activities of enzymes of the pentose phosphate pathway, except for transketolase activity, which fell to 50% of the control value. Little change occurred in adipose-tissue weight or protein content. 5. Adrenalectomy caused a decrease of 40% in the activity of glucose 6-phosphate dehydrogenase and of 20-30% in the activities of the remaining enzymes of the pentose phosphate pathway; hexokinase activity was also decreased. Treatment with cortisone for 3 days did not significantly raise the activity from that found in adrenalectomized rats. Treatment of normal rats with high doses of cortisone had no significant effect on the activities of the enzymes of the pentose phosphate pathway in adipose tissue. 6. The changes in enzyme activities are discussed in relation to: (a) the concept of constant-proportion groups of enzymes; (b) the known changes in the flux of glucose through alternative metabolic pathways; (c) the pattern of change found in liver with similar hormonal and dietary conditions.
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PMID:The pentose phosphate pathway of glucose metabolism. Hormonal and dietary control of the oxidative nd non-oxidative reactions and related enzymes of the cycle in adipose tissue. 581 81

Increased activity of 6-phosphogluconate dehydrogenase was found in human colon tumors as compared to the adjacent unaffected mucosa. Glucose 1,6-diphosphate (Glc-1,6-P2), an endogenous potent regulator of glucose metabolism, markedly inhibited the activity of 6-phosphogluconate dehydrogenase (6-PGD) in extracts of the normal and malignant human colon. Glc-1,6-P2 also inhibited the activity of hexokinase in these extracts. The endogenous levels of Glc-1,6-P2 in the colon and tumors were measured. Since the pentose cycle can be inhibited by Glc-1,6-P2, means to increase endogenous levels of Glc-1,6-P2 or to introduce it into cells, might result in antitumor effects.
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PMID:Inhibition of 6-phosphogluconate dehydrogenase by glucose 1,6-diphosphate in human normal and malignant colon extracts. 623 85

The activities of key enzymes of glycolysis and of the glucose shunt as well as the capacity of lactic acid formation were determined in the high-speed tissue supernatant of the transplantable Albert hepatoma of mouse [originally produced by oral application of chrysoidin (2,4-diaminoazobenzene) on C57 Black mice]. Furthermore, the particle-bound hexokinase activity was determined. The following results were obtained: In the hepatoma the activities of aldolase, pyruvate kinase and lactic dehydrogenase are hardly altered compared with normal liver. The activities of hexokinase and phosphofructokinase are increased 2,5-fold, those of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase 2-fold. The capacity for lactic acid formation from glucose is 7 times as high in the hepatoma supernatant. Strong differences emerge from the liver-to-hepatoma relationship in terms of intracellular distribution of the hexokinase (total homogenate 1 : 5, supernatant 1 : 2,5 and particle-bound hexokinase activity 1 : 18). A summarizing consideration of all the results obtained so far for the Albert hepatoma shows that this malignoma departss in several biochemical parameters from the "Molecular Correlation Concept" maintained by Weber, providing more evidence for the individuality of tumors.
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PMID:[Activities of several enzymes of glycolysis and of the glucose shunt in the Albert hepatoma of mouse (author's transl)]. 625 66

The effect of adrenalectomy on specific activities of testicular hexokinase, 6-phosphofructokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glycogen concentration have been studied. A general increase in specific activities of all enzymes was seen after adrenalectomy in rats of all ages studied. However, lactate dehydrogenase activity and glycogen concentration in pre-pubertal rats alone were depleted with no alteration in pubertal and adult animals. This was accompanied by increased prolactin titres, but gonadotrophins and testosterone were unaltered. Dexamethasone treatment returned all enzyme activities and hormonal profiles to normal.
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PMID:Effect of adrenalectomy and dexamethasone treatment on testicular enzymes involved in carbohydrate metabolism. 630 9

The levels of glucose 1,6-bisphosphate (Glc-1,6-P2), the powerful regulator of carbohydrate metabolism, changed in rat skin during growth: Glc-1,6-P2 increased during the first week of age, and thereafter was dramatically reduced during maturation. The activity of glucose 1,6-bisphosphatase, the enzyme that degradates Glc-1,6-P2, changed with age in an invert manner as compared to the changes in Glc-1,6-P2. These findings suggest that the age dependent changes in this enzyme's activity may account for the changes in intracellular Glc-1,6-P2 concentration. The age-related changes in Glc-1,6-P2 were accompanied by concomitant changes in the activities of particulate (mitochondrial) hexokinase and 6-phosphogluconate dehydrogenase, the two enzymes known to be inhibited by Glc-1,6-P2. The activities of both these enzymes in the soluble fraction were not changed with age. The particulate enzymes were more susceptible to inhibition by Glc-1,6-P2 than the soluble activities, which may explain why only the particulate, but not the soluble activities, correlated with the age-dependent changes in tissue Glc-1,6-P2. These results suggest that the changes in particulate hexokinase and 6-phosphogluconate dehydrogenase resulted from changes in intracellular concentration of Glc-1,6-P2. The marked reduction in Glc-1,6-P2 during maturation, accompanied by activation of mitochondrial hexokinase and 6-phosphogluconate dehydrogenase, may reflect an enhancement in skin metabolism during growth.
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PMID:Age-dependent changes in glucose 1,6-bisphosphate levels and in the activities of glucose 1,6-bisphosphatase, and particulate hexokinase and 6-phosphogluconate dehydrogenase in rat skin. 631 42

The requirements of a cloned macrophage-like cell line, J774.16, for oxygen metabolism, and the nature of the defect in oxidative metabolism in a variant clone derived from it, J774.C3C, were studied. Upon stimulation with phorbol myristate acetate (PMA), the parental clone produced approximately 1 nmol O2-/min/10(6) cells, whereas the variant clone produced no detectable O2- under the same conditions. Sustained O2- production by J774.16 was totally dependent on extracellular glucose; in glucose-free medium, the cells initiated O2- production but could not sustain it. When cells were stimulated with PMA, glucose-C-1 oxidation of J774.16 cells increased 20-fold while that of J774.C3C remained at resting levels. O2- production in J774.16 cells was inhibited by some agents known to block mitochondrial electron transport before coenzyme Q, such as rotenone and tetrathiafulvalene, whereas antimycin A enhanced O2- production. A dissociation between O2- production and glucose-C-1 oxidation was observed when J774.16 was treated with certain metabolic inhibitors. Quinacrine, 2,4-dinitrophenol, chlorpromazine, and trifluoperazine inhibited O2- production completely under conditions in which glucose-C-1 oxidation was reduced only by 30%. Rotenone inhibited O2- production with no effect on glucose-C-1 oxidation whereas antimycin A augmented O2- production 50% but inhibited glucose oxidation by 20%. Glucose transport studies, with 2-deoxy-D-glucose, showed that the Km for glucose transport of both clones was about 1 mM, indicating that cells could effectively transport glucose even at low concentrations. The Vmax for glucose transport in both J774.16 and variant J774.C3C cells doubled after PMA stimulation, indicating that the variant was effectively stimulated by PMA, even though O2- was not produced. Similarly, PMA induced protein phosphorylation in both clones. No differences between clones J774.16 and J774.C3C in hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glutathione reductase, or glutathione peroxidase activities could be found. When dithionite-reduced and -oxidized difference spectra of plasma membranes of these clones were compared, comparable levels of b-type cytochrome were found in both clones. However, CO difference spectra indicated that CO was bound to a b-type cytochrome (presumed to be b-245) in clone J774.16 but not in J774.C3C.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Oxygen metabolism in cloned macrophage cell lines: glucose dependence of superoxide production, metabolic and spectral analysis. 631 50

The effect of adrenalectomy and corticosterone replacement on epididymal enzymes involved in obligatory steps of glycolysis and pentose phosphate pathway were studied along with serum hormonal profiles. Adrenalectomy was found to elevate serum prolactin while the gonadotropins and testosterone were unaltered. In caput epididymal tissue enzymes of the pentose phosphate pathway. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were increased after adrenalectomy. However, in corpus epididymal tissue the key enzymes viz. hexokinase, 6-phosphofructokinase and pyruvatekinase of the glycolytic pathway were elevated leaving the pentose phosphate pathway unaffected. Adrenalectomy was also found to favour glycolysis of the epididymal spermatozoa. The possible direct effect of prolactin is discussed to explain the enzymatic changes in epididymis. Corticosterone replacement was found to maintain the enzyme activities along with serum prolactin and corticosterone at control levels. In conclusion, it is suggested that the adrenalectomy induced changes in enzyme activities could be due to the direct effect of prolactin.
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PMID:Effect of adrenalectomy and corticosterone replacement on epididymal carbohydrate metabolism--studies on mature male rats. 640 94


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