Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Chronic (6 days) hyperinsulinaemia in young rats produced lower blood glucose concentrations and augmented body- and liver-weight gain. The insulin-treated rats had increased hepatic activities of citrate-cleavage enzyme, 'malic' enzyme and high-substrate (6.6 mM-phosphoenolpyruvate) pyruvate kinase, and decreased glucose 6-phosphatase. There were no changes in activities of phosphoenolpyruvate carboxykinase, phosphofructokinase, low-substrate (1.3 mM-phosphoenolpyruvate) pyruvate kinase, glucokinase and hexokinase.
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PMID:Effects of chronic hyperinsulinaemia on hepatic enzymes involved in lipogenesis and carbohydrate metabolism in the young rat. 66 50

In a theoretical study the influence of hemoglobin and Mg-ions as binding partners of red cell 2,3-diphosphoglycerate and ATP was investigated. Free hemoglobin may be an efficient competitor of Mg2+ for the ligand ATP. At conditions which favour hemoglobin as binding partner (i.e. desoxygenation, low medium pH and incubation temperature, as in blood preservation) up to 95% of the whole cellular ATP (ca. 2mM in cell water) may be bound to hemoglobin (ca. 7 mM). This binding is largely prevented in the presence of physiological amounts of diphosphoglycerate (ca. 7 mM) which is in excess and has a higher binding affinity to hemoglobin. Therefore, diphosphoglycerate keeps ATP (MgATP) in cell water solution at conditions in which Hb would trop it in the presence of Mg2+ (ca. 3mM). It can be calculated that, by lack of free MgATP, the activity of hexokinase within the cell drops by a factor of greater than 10 when diphosphoglycerate is metabolized. This indirect activation by diphosphoglycerate of hexokinase is operative at free concentrations of DPG far below those which exert the well known excess inhibitory effect on hexokinase and phosphofructokinase. In a model study, the activation by diphosphoglycerate of the initial two-kinase stage was introduced into a simplified kinetic model of glycolysis. A pronounced hysteresis loop of the stationary concentrations of ATP and diphosphoglycerate was produced indicating the existence of several stationary states, one with high ATP and high diphosphoglycerate, the other one with low values. It is demonstrated that diphosphoglycerate, being a protector of glycolysis at physiological concentrations, triggers an autocatalytic breakdown of the energy state when permitted to drop to low values.
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PMID:[Importance of binding of 2,3-diphosphoglycerate and ATP to hemoglobin for erythrocyte glycolysis: activation by 2,3-diphosphoglycerate of hexokinase at intracellular conditions]. 70 29

Untrained healthy male volunteers were studied to observe the effects of physical exercise (bicycle ergometer, 920 kpm/min for 10 min, 15 min and 30 min) upon glycolytic intermediates in red blood cells. The levels of glucose 6-phosphate, fructose 6-phosphate, pyruvate and lactate increased after each exercise. The levels of fructose 1,6-diphosphate increased and phosphoenolpyruvate decreased respectively only after 30 min of exercise. At the rest period of 30 min after 30 min of exercise the lactate level still remained unchanged, however all the other intermediates returned to the preexercise values. A negative crossover point seemed to exist between fructose 6-phosphate and fructose 1, 6-diphosphate after 15 min of exercise. A positive crossover point was observed between phosphoenolpyruvate and pyruvate after 30 min of exercise. There were significant increases in hexokinase and pyruvate kinase activities, but not in phosphofructokinase activity after 30 min of exercise. These facts suggested that the increase in pyruvate kinase activity was due to the elevated fructose 1,6-diphosphate level after 30 min of exercise. A significant increase in plasma dopamine-beta-hydroxylase activity was found after each exercise. A close positive correlation was observed between pyruvate-phosphoenolpyruvate ratio and dopamine-beta-hydroxylase activity after 30 min of exercise. It was suggested that pyruvate-phosphoenolpyruvate ratio provided a reliable index of physical exercise.
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PMID:[Effect of physical exercise on glycolysis in human red blood cells (author's transl)]. 71 Nov 26

The stability of various glycolytic enzymes of human erythrocytes has been studied by the mechanical shaking method. The rate of denaturation apparently followed first order kinetics. The t1/2, the shaking time required to denature 50% of the original activity, for glucose-6-phosphate dehydrogenase, phosphofructokinase, and pyruvate kinase was less than 1 min; that for hexokinase, 6-phosphogluconate dehydrogenase, and monophosphoglyceromutase was between 2 and 13 min; that for all the other enzymes was more than 30 min. Since the t1/2 value for each enzyme is highly reproducible if the shaking conditions are kept constant, these parameters may be used as an indicator of protein stability in solution. The mechanical denaturation method may also be used to remove unstable components from a mixture of proteins with different stabilities.
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PMID:Stability of glycolytic enzymes of human erythrocytes. 83 47

Enzyme abnormalities are frequently found in the red cells of patients with various acquired blood disorders. In leukaemias, preleukaemic states and bone marrow insufficiencies with or without sideroblastosis, changes in enzyme activity are usually characterized by the coexistence of deficiency of some enzymes and an increased activity of others. The most frequently decreased activities are those of pyruvate kinase, phosphofructokinase,2,3-diphosphoglycerate mutase and adenylate kinase; the most frequently increased activities are those of hexokinase, aldolase, enolase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase. In primary myelofibrosis and in polycythaemia rubra vera, enzyme deficiencies are infrequent and differ from those observed in leukaemias and related disorders. Phosphohexose isomerase and phosphoglucomutase deficiencies seem relatively specific for polycythaemia rubra vera. Explanations for the acquired enzymopathies are still at the stage of hypothesis. The theory of multiple genetic damage may explain some findings but has not yet been proved right. The possibility of post-translational molecular modification is suggested as a working hypothesis.
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PMID:Acquired erythroenzymopathies in blood disorders: study of 200 cases. 107 44

Glucose disappearance and lactate production by the rat thymocytes are stimulated significantly 45 min after addition of phytohaemagglutinin or concanavalin A and the stimulated rate is sustained for at least 8 h. Changes in the steady-state concentration of glycolytic intermediates that occur at non-equilibrium steps during the increased rate of glycolytic flux indicate that the glucose carrier, hexokinase and phosphofructokinase are potentially regulatory steps that undergo nearly simultaneous or tightly sequential activation following interaction of the cells with the mitogen.
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PMID:Phytohaemagglutinin stimulation of rat thymus lymphocytes glycolysis. 108 66

The erythrocytes of 350 pigtailed macaques (Macaca nemestrina) were examined for electrophoretic variation of hemoglobin and 26 enzymes. Seven enzymes showed variation in more than 1% of individuals: phosphoglucose isomerase, phosphoglucomutase-1, soluble NADP-dependent isocitric dehydrogenase, peptidase A, peptidase C, 2,3-diphosphoglycerate mutase, and acid phosphatase. Variation with lesser frequency was found in soluble glutamic-oxalacetic transaminase, phosphoglycerate kinase, lactic dehydrogenase, and hemoglobin. Only eight samples were tested for esterase D, and one of these had a variant phenotype. Enzymes with no clear variation were adenylate kinase, adenosine deaminase, phosphofructokinase, hexokinase, pyruvate kinase, glyceraldehyde 3-phosphate dehydrogenase, aldolase, phosphoglycerate mutase, phosphopyruvate hydratase (enolase), phosphoglucomutase-3, and superoxide dismutase. There was father-to-son transmission of PGI, PGM-1, peptidase C, 6PGD, 2,3-DPGAM, NADP-ICD, and acid phosphatase variants, suggesting that these loci are autosomal as in man.
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PMID:Intraspecific red cell enzyme variation in the pigtailed macaque (Macaca nemestrina). 114 87

The dynamics of glycolysis and glycogenolysis in the postnatal period, determined from the accumulation of lactate in the homogenate of the heart muscle, indicates that the glycolytic activity begins to subside right after the birth and becomes constant after a lapse of 15-20 days. The activity of the phosphorylase, phosphohexoisomerase, enolase and pyruvate-kinase in the heart muscle extract was found to remain virtually unchanged. Some decline is noted in the activity of the aldolase and hexokinase, while that of the phosphofructokinase and lactate-dehydrogenase rises by 50-60 per cent. These data suggest that in the early ontogenesis the increasing capacity of the mitochondrial system in the heart muscle is paralled by an adjustable conditioned inhibition of the glycolytic phosphorylation, with concurrently rising activity of the phosphofructokinas and, consequently, also of the potential capacity of glycolysis and glycogenolysis.
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PMID:[Dynamics of carbohydrate metabolism in the heart muscle in early ontogenesis]. 116 19

The realtionship between growth rate and the metabolic activity of certain liver enzymes was studied using two strains of White Plymouth Rock chickens which had been selected in divergent directions for eight-week body weight. The activities of hexokinase, glucokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, citrate synthase, glycogen synthetase, glutamate dehydrogenase and aspartate transaminase were measured at 4, 8 and 20 weeks of age. The mean percentage rate of growth of the birds selected for high eight-week body weight exceeded that of the birds selected for low eight-week body weight only during the early growth period. Thereafter, and until sexual maturity, the low-line birds grew at a faster rate, relative to body size. The mature body weight of the high-line birds exceeded that of the low-line birds by a factor of approximately 1.5. A close similarity was noted between the metabolic activity of certain liver enzymes and the growth rate (relative to body size) of the birds studied. At four and eight weeks of age, the faster-growing birds (whether high- or low-line) generally exhibited a greater capacity for glucose phosphorylation and glycolysis, but a poorer capacity for glycogen synthesis, than the slower-growing birds. At twenty weeks, growth rate and metabolic activity were similar in both strains.
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PMID:Activity of certain liver enzymes in fast- and slow-growing lines of chickens. 118 17

The effect of adenylic acid, glucose-6-phosphate, fructose-1,6-diphosphate and phosphoenolpyruvate on creatine kinase isoenzymes (brain extract, muscle and heart extracts and purified muscle enzyme) was studied. These effectors, especially phosphoenolpyruvate, are shown to inhibit in different degree the reaction of ATP formation catalysed by creatine kinase from all tissues. The effectors do not inhibit the creatine phosphate synthesis in extracts, but depress purified creatine kinase. The interrelationship of the creatine kinase system and the key glycolytic enzymes (phosphofructokinase, hexokinase, pyruvate kinase) is discussed.
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PMID:[The effect of sugar phosphates, phosphoenolpyruvate and adenylic acid on muscle, brain and heart creatine kinases]. 121 66


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