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)

Effects of glucose concentration and anoxia upon the metabolite concentrations and rates of glycolysis and respiration have been investigated in the perfused liver of the fetal guinea pig. In most cases the metabolite concentrations in the perfused liver were similar to those observed in vivo. Between 50 days and term there was a fall in the respiratory rate and in the concentration of ATP and fructose 1,6-diphosphate and an increase in the concentration of glutamate, glycogen and glucose. Reducing the medium glucose concentration from 10 mM to 1 mM or 0.1 mM depressed lactate production and the concentration of most of the phosphorylated intermediates (except 6-phosphogluconate) in the liver of the 50-day fetus. This indicates a fall in glycolytic rate which is not in accord with the known kinetic properties of hexokinase in the fetal liver. Anoxia increased lactate production by, and the concentrations of, the hexose phosphates ADP and AMP in the 50-day to term fetal liver, while the concentration of ribulose 5-phosphate, ATP and some triose phosphates fell. These results are consistent with an activation of glycolysis, particularly at phosphofructokinase and of a reduction in pentose phosphate pathway activity, particularly at 6-phosphogluconate dehydrogenase. The calculated cytosolic NAD+/NADH ratio for the perfused liver was similar to that measured in vivo and evidence is presented to suggest that the dihydroxyacetone phosphate/glycerol 3-phosphate ratio gives a better indication of cytosolic redox than the lactate/pyruvate ratio. The present observations indicate that phosphofructokinase hexokinase and possibly pyruvate kinase control the glycolytic rate and that glyceraldehyde-3-phosphate dehydrogenase is at equilibrium in the perfused liver of the fetal guinea pig.
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PMID:Some effects of glucose concentration and anoxia on glycolysis and metabolite concentrations in the perfused liver of fetal guinea pig. 2 74

1) The rate of 2,3-bisphosphoglycerate breakdown is independent of pH value. 2) The adenine nucleotide pattern at alkaline pH values with its characteristic lowering of ATP and the accompanying accumulation of fructose-1,6-bisphosphate is caused by a relative excess of the activity of the hexokinase-phosphofructokinase system as compared wity pyruvate kinase. 3) The breakdown of adenine nucleotides proceeds via AMP mainly through phosphatase and not via AMP deaminase. 4) The constancy of the sum of nucleotides as long as glucose is present is postulated to be due to resynthesis via adenosine kinase which competes successfully with adenosine deaminase. 5) A procedure is given to calculate ATPase activity of glucose-depleted red cells. The results indicate that the ATPase activity is less at lower pH values and declines with time. An ATPase with a high Km for ATP is postulated. 6) During glucose depletion ATP production is mostly derived from the breakdown of 2,3-bisphosphoglycerate and the supply from the pentose phosphate pool both of which proceed at a constant rate. The contribution of pentose phosphate from the breakdown of adenine nucleotides amounts to 40% of the lactate formed at pH 6.8 and is about twice the lactate at pH 8.1.
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PMID:The breakdown of adenine nucleotides in glucose-depleted human red cells. 4 52

The activity of enzymes regulating the processes providing functional activity of leukocytes was studied in the exudate leukocytes of healthy rabbits and animals with alloxan diabetes. Rabbits with diabetes displayed a reduction of hexokinase, phosphoglucomutase, glucose-6-phosphate dehydrogenase and adenylate kinase activity. The activity of UDPH-pyrophosphorylase, UDPH-glycogentranspherase, 6-phosphogluconate dehydrogenase and glutathion reductase showed no significant changes in the exudate leukocytes in diabetes. A reduction of hexokinase and glucose-6-phosphate dehydrogenase limiting glycolysis and the pentose-phosphate cycle, respectively, providing energy for leukocytes and important in protein metabolism of these cells, is of great significance in the reduction of functional activity of leukocytes in the inflammatory focus in diabetes.
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PMID:[Enzymatic profile of the exudate leukocytes in diabetes mellitus]. 9 55

The R3230AC mammary adenocarcinoma was not dependent on insulin; tumor growth was equal to or greater in diabetic rats than in intact animals. However, tumor growth was reduced when daily doses of insulin were administered. Treatment with estrogen inhibited growth of the R3230AC carcinoma, either in diabetic rats or in intact animals simultaneously treated with insulin. The effects of insulin plus estrogen treatment appeared to be additive in causing inhibition of tumor growth. Tumors from diabetic rats showed few metabolic alterations as reflected by little or no changes in the activities of selected glycolytic enzymes, pyruvate kinase, phosphofructokinase, and hexokinase, nor any striking changes in the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, representing the pentose phosphate pathway. A modest reduction in the ratio of utilization of (1-14C)glucose: (6-14C)glucose was seen in vitro by tumors from diabetic rats. It was concluded that insulin, along with estrogen and prolactin, should be considered as a hormonal factor that influences growth of this automonous, hormone-responsive adenocarcinoma.
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PMID:Influence of insulin on estrogen-induced responses in the r3230ac mammary carcinoma. 12 68

The behavior of enzyme activities, substrates and metabolites of glycosis as well as of the pentose phosphate shunt following local irradiation (250 to 6000 R surface dose) is biochemically investigated in the guinea-pig's myocardium. During irradiation, an activation of phosphorylase-a is going on while the total phosphorylase content remains unchanged. Enzyme activities of hexokinase and phosphofructokinase are increased in dependence on dosage as well as time. The glycogen content is being reduced; tissular concentration of the metabolites glucose-1-phosphate, glucose-6-phosphate, glyceraldehyde-3-phosphate, glycerol-3-phosphate, and pyruvate increases following irradiation; the content of fructose-1,6-diphosphate, dihydroxyacetonephosphate, and lactate is decreased. The activity of glucose-6-phosphate dehydrogenas is slightly inhibited, whereas 6-phosphogluconate-dehydrogenase remains unaffected.
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PMID:[Studies on the effect of radiation on electrolyte changes and metabolism of the myocardium. V. Changes in enzyme activities and glycolysis metabloites due to radiation]. 12 7

Adipose tissue and liver from vitamin B6-deficient rats have an increased lipogenic capacity. Whether this phenomenon is accompanied by changes in the activities of certain enzymes involved in the metabolism of carbohydrate and lipid, or by altered transport of glucose into adipocytes, has been studied. Five glycolytic enzymes (hexokinase, phosphoglucose isomerase, phosphofructokinase, aldolase, and pyruvate kinase), two pentose phosphate pathway enzymes (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase), malic enzyme, and ATP citrate lyase were measured in the epididymal adipose tissue, livers and kidneys of vitamin B6-deficient and control rats. Vitamin B6 deficiency did not significantly affect the glycolytic enzyme levels in the tissues studied, or the dehydrogenases measured in adipose tissue and kidneys. Liver glucose-6-phosphate dehydrogenase, and adipose tissue and liver malic enzyme were significantly lowered in deficient rats compared to ad libitum and pair-fed controls. Adipose tissue and liver ATP citrate lyase activities were also significantly decreased by vitamin B6 deficiency. In the presence of insulin, the uptake of glucose and 3-O-methyl glucose, a non-metabolizable sugar, by fat pads from deficient rats was greater than uptake by fat pads from control rats. These observations suggest that the increased glucose utilization by adipose tissue and liver of vitamin B6-deficient rats is not directly related to changes in the enzymes studied, but in the case of adipose tissue, may be explained, at least in part, by enhanced glucose uptake.
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PMID:Effects of vitamin B6 deficiency on liver, kidney, and adipose tissue enzymes associated with carbohydrate and lipid metabolism, and on glucose uptake by rat epididymal adipose tissue. 13 63

A quantitative enzyme analysis of 32 fetal human brains of 6--42 weeks gestational age range was carried out for the major glycolytic and pentose phosphate shunt enzymes. A critical period of raised enzyme levels was observed at 14 weeks. The glycolytic rate was probably controlled by the activities of hexokinase and phosphofructokinase which appear from the development patterns to have independent genetic sites. A rise in most enzyme activities was experienced in the final weeks of gestation towards levels consistent with those of adult tissues. Pentose phosphate shunt enzyme levels remained virtually unchanged during gestation after 14 weeks.
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PMID:The development of glycolytic and pentose phosphate shunt enzymes in human brain. 14 Jul 9

The activity of hexokinase, dehydrogenases of pentose cycle, total lactate dehydrogenase, and cytochrome-C-oxidase level was determined in the aorta of rats with hyperthyroidism caused by the intraperitoneal administration of L-thyroxin. In the administration of hormone doses approaching the physiological ones there was an increase in the activity of cytochrome-C-oxidase and a tendency to the increase of 6-phosphogluconate dehydrogenase. Elevation of the activity of all the enzymes under study, excluding lactate dehydrogenase, and in increase of the amount of extractable protein occurred in the administration of moderate thyroxin doses. An increase of hexokinase and particularly of cytochrome-C-oxidase activity was revealed in hyperthyroidism with phenomena of thyrotoxicosis. The activity of the rest of the enzymes approached control. The data obtained are discussed from the point of view of the role played by thyroid hormones in the pathogenesis of atherosclerosis.
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PMID:[Effect of thyroxine on oxidative enzymatic activity in the rat aorta]. 21 88

The activities of the key gluconeogenic, glycolytic, and pentose-shunt enzymes in chicken kidney were determined starting from 8 days before to 58 days after hatching. The activities of pyruvate carboxylase (PC), mitochondrial and cytosolic phosphoenolypruvate carboxykinase (PEPCK), fructose-1,6-diphosphatase (FDPase) and glucose-6-phosphatase (G6Pase) were low in the embryonic tissue but increased towards the time of hatching. After hatching, the activities of PC, mitochondrial PEPCK, and G6Pase continued to increase, but those of FDPase and cytosolic PEPCK decreased. Relatively little change in these activities was observed in chickens over 24 days old. The activities of hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) increased during embryonic growth. After hatching, HK activity continued to increase and then decrease, whereas PFK appeared to decrease and then increase to prehatch levels in 28-day-old birds. LDH activity continued to increase until 8 days after hatching and remained constant thereafter. No definite pattern was discernible in the case of PK. As for the pentose-shunt enzymes, there was no significant change in glucose-6-phosphate dehydrogenase activity (G6PDH), but the activity of 6-phosphogluconate dehydrogenase (6PGDH) increased until the chickens were 14 days old and then remained relatively constant.
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PMID:Development of gluconeogenic, glycolytic, and pentose-shunt enzymes in the chicken kidney. 22 78

Carbohydrate metabolism by four rat hepatoma cell lines in culture, namely, Reuber H35, MH1C1, RLC, and HTC, has been investigated. Glucose utilization by H35 and MH1C1 cells is lower than that by RLC and HTC cells. The four cell lines also differ with respect to the accumulation of lactic acid in the growth medium; in particular, H35 cells show uptake of lactic acid, rather than accumulation in the medium. Specific activities of a number of enzymes involved in glycolysis, gluconeogenesis, pentose phosphate pathway, and glycogen formation were determined in the four cell lines. A direct relationship between the differences was found for the activities of some enzymes belonging to carbohydrate metabolism, namely, hexokinase, pyruvate kinase, aldolases A and B, glucose-6-phosphate dehydrogenase, and phosphogluconate dehydrogenase and the differences found for glucose utilization by the different cell lines.
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PMID:Comparative studies of glucose metabolism in HTC, RLC, MH1C1, and Reuber H35 rat hepatoma cells. 42 45


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