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)

The activities of hexokinase, glucokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, and fructose-1,6-diphosphatase were determined in loach embryos developed in solutions of insulin, hydrocortisone, estrone and thyroxin at different stages of embryogenesis. Glucokinase and fructose-1,6-diphosphatase activties are shown not to change markedly under the influence of the above-mentioned hormones. During some periods of early development the hexokinase activity is inhibited by insulin, estrone and thyroxin. The glucose-6-phosphate dehydrogenase activity is suppressed by each of the used hormones at all the stages of early embryogenesis while the glocose-6-phosphatase activity decreased only under the influence of insulin at the cleavage, blastula and gastrula stages. Insulin increased the activity of phosphofructokinase at the cleavage, blastula and early gastrula stages and hydrocortisone, estrone and thyroxine during certain periods of these stages. From middle gastrula two last hormones decreased the phosphofructokinase activity in the loach embryos.
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PMID:[Activity of carbohydrate metabolism enzymes in loach embryos under the influence of hormones]. 19 80

It is established that in embryos incubated until the early blastula stage in the solution of insulin with addition of cycloheximide or puromycin, there is neither a decrease in the hexokinase and glucose-61 phosphate dehydrogenase activities nor an increase in the phosphofructokinase activity, as it is shown under the influence of insulin only. Puromycin removes an inhibitory effect of insulin on the glucose-6-phosphatase activity, and actinomycin D removes this influence with respect to glucose-6-phosphate dehydrogenase and glucose-6-phosphatase activities. The addition of antibiotics removes inhibition of the hexokinase, glucose-6-phosphate dehydrogenase and glucose-6-phosphatase activities by the hormone in the unfertilized eggs as well. Actinomycin D alone inhibits the hexokinase and activates the phosphofructokinase activities in the embryos and eggs, puromycin decreases their hexokinase activity and cycloheximide has the same effect on the glucose-6-phosphatase activity in the embryos only.
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PMID:[Effect of insulin on activity of carbohydrate metabolism enzymes in loach embryos in early development]. 19 74

The adenylate kinase system offers a mechanism for the rapid provision of energy by catalysing the production of ATP from ADP. Fluormetric micromethods were developed for determination of the activity of this enzyme using either formation of ADP or ATP, in each case measured by coupling to suitable dehydrogenase reactions. Both procedures yielded results in good agreement, but when ADP formation was measured an interfering phosphatase splitting of ATP had to be corrected for. Therefore, ADP was preferred as the substrate and its conversion to ATP was determined in a coupled hexokinase-glucose-6-phosphate dehydrogenase reaction yielding stoichiometric amounts of NADPH which were measured by the native fluorescence of this form of the nucleotide. The sensitivity and reproducibility of our micro-method permitted assay of small samples (50-500 ng) such as a layer of cerebellar cortical nerve cells and of insulin producing cells from the islets of Langerhans. Although not reaching the high values in muscle, these cells showed significantly higher activities than parenchymatous cells from the liver and the exocrine pancreas. The sensitivity attained is more than required for assay of clinical fine needle biopsies and is quite satisfactory for detection and estimation of adenylate kinase contaminants in enzyme preparations.
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PMID:Fluorometric microassays of adenylate kinase, an enzyme important in energy metabolism. 20 11

Epinephrine, hydrocortisone, and dibutyril cAMP inhibited glycolysis and glucogenolysis. The inhibitory effect was also found when glucose-6-phosphate (G-6-P) was used as a glycolysis substrate, but not for fructose-1,6-diphosphate. This is the evidence of hexokinase activity inhibition by hormones and dibutyril cAMP, and presumably of phospholylase and phosphofructokinase as well. In the simulated cell-free system the hormones produced no effect, dibutyril cAMP inhibiting hexokinase alone. For the realization of hormones effect their interaction with the cell membrane is required. Inhibition of glycogen and G-6-P decomposition to lactic acid in the rat liver slices was not associated with the hormone action on phosphorylase and phosphofructokinase through cAMP and proteinkinase directly. The results obtained indicated the existence of a supplementary mechanism that modified cAMP effect on the activity of the said enzymes. Insulin was effective in any of the cases.
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PMID:[Effect of adrenaline, hydrocortisone, insulin and dibutyryl-cAMP on glycolysis and glycogenolysis in white rat liver slices]. 21 83

Hyperinsulinemia was produced in fetal rhesus monkeys for 21 days in the last third of gestation by subcutaneous pork insulin injected at 19 U a day. Plasma insulin concentrations in treated fetuses (N = 4) were 3525 microU/ml. There was no difference in paired pre- and post-treatment fetal plasma glucose concentration. Activity of the hepatic enzymes that promote glucose utilization (glucokinase and hexokinase) and glycolysis (phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase) was unaffected. Similarly, glycogen metabolism enzymes (active and inactive synthase and phosphorylase) were unaltered. Two gluconeogenic enzymes (PEPCK and glucose-6-phosphatase) were diminished in the treated group compared with controls. Fetal hyperinsulinemia enhanced lipogenic and NADPH-producing enzyme activities, as evidenced by a twofold increase in fatty acid synthase and in citrate cleavage enzyme activity. Malic enzyme was absent. Hyperinsulinemia with euglycemia (1) increases the activity of enzymes that participate in lipogenesis, (2) decreases some of those controlling gluconeogenesis, and (3) has no effect on the enzymes of glycolysis.
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PMID:Chronic hyperinsulinemia in the fetal rhesus monkey: effects on hepatic enzymes active in lipogenesis and carbohydrate metabolism. 22 50

The polymorphonuclear leukocyte (PMNL) depends on glucose as a source of energy for motility, chemotaxis, phagocytosis, and bactericidal activity. Activated complement (C5a) at low concentrations stimulates carrier-mediated carbohydrate transport in PMNLs as measured by the uptake of 2-deoxy-D-[(3)H]glucose. Human PMNLs were preincubated at 37 degrees C for 15 min with zymosan-activated human serum or various purified preparations of human C5a. A concentration-dependent increase in deoxyglucose transport (>700% of control) into PMNLs occurred with all test substances. Reaction was linear for 30 min, and uptake of deoxyglucose followed saturation kinetics. C5a caused a decrease in the K(m) for deoxyglucose, from 0.53 to 0.11 mM, without altering the V(max) (44 nmol/30 min per 5 x 10(6) PMNLs in control and 46.6 with C5a). The optimal concentration of C5a for enhanced carrier-mediated transport of deoxyglucose was similar to that which promoted optimal chemotaxis. Activated serum from C5-deficient mice had little or no effect on deoxyglucose transport whereas that from normal syngeneic mice enhanced deoxyglucose transport. C5a did not enhance deoxyglucose transport into isolated erythrocytes, platelets, or lymphocytes. The deoxyglucose within the cell was primarily in the phosphorylated form, and hexokinase activity was not increased in PMNLs stimulated with C5a, indicating that hexokinase was not rate limiting and that enhanced transport was the mechanism of the C5a activity. Insulin at physiologic concentration (10 ng/ml) had no effect on deoxyglucose transport in PMNL and did not act as a competitive inhibitor of C5a. This insulin-like bioactivity could be detected with the amount of C5a that would be present after activation of 0.1-0.5% of the C5 in 1 ml of serum. This suggests that uptake of [(3)H]deoxyglucose by PMNLs might serve as a highly sensitive test for activation of the fifth component of complement.
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PMID:Enhancement of hexose uptake in human polymorphonuclear leukocytes by activated complement component C5a. 29 91

The metabolic and morphologic adaptation to physical training in skeletal muscle tissue of eleven middle-aged, physically untrained men was studied. Muscle biopsies were taken from the vastus lateralis before, after 8 weeks and after 6 months of physical training for analysis of metabolic and morphologic variables. Glucose tolerance test indicated increased insulin sensitivity after 6 months of physical training. The activities of glycogen phosphorylase, hexokinase and glucose-6-P-dehydrogenase were increased but other enzymes involved in glycogen turnover and glycolysis were unchanged after 6 months of physical traning. The activities of citrate synthase and cytochrome-c-oxidase, representing the oxidative capacity were significantly increased already after 8 weeks of physical training. The incorporation rate of palmitate-carbon into CO2 and triglycerides increased, and the incorporation rate of leucine-carbon into CO2 decreased with 6 months of physical training. The fiber diameter of both Type 1- and Type 2-fibers increased, while the mitochondrial volume increased predominantly in Type 2-fibers. Significant correlations were found between metabolic, physiologic and morphologic variables before and after physical training. The results indicate an increased oxidative capacity, mainly located to Type 2-fibers, and an increased utilization of fatty acids in response to this type of physical training.
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PMID:Physical training in man. Skeletal muscle metabolism in relation to muscle morphology and running ability. 32 4

Parenchymal cells from adult rat liver, isolated by a collagenase perfusion technique, have been maintained in primary culture and a detailed study on carbohydrate metabolism carried out over the initial 48-hour culture period. The glucose concentration of the medium exerts a major influence on glycogen accumulation by the cells. Insulin, particularly at high glucose concentrations, stimulates glycogen biosynthesis, whereas glucagon prevents glycogen accumulation. Dexamethasone was without effect on glycogen metabolism. Glucose appears to stimulate glycogen accumulation by activation of glycogen synthetase enzyme. However, there is a gradual loss of synthetase activity throughout the culture period. Similar decreases in activity were noted for pyruvate kinase, aldolase and hexokinase. Glucose, insulin and dexamethasone were unable to prevent these decreases in enzyme activity. Foetal bovine serum contains fructose and this hexose appears to be the factor in serum which is responsible for the activation of glycogen accumulation in the presence of physiological glucose concentrations. The lactic acid content of the serum may also stimulate glycogen accumulation. In general, there is a gradual loss of the pattern of carbohydrate metabolism typical of differentiated hepatocytes during the culture period.
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PMID:Effects of hormones and serum on glycogen metabolism in adult rat liver parenchymal cell primary cultures. 40 98

Effects of hydrocortisone and insulin on activities of hexokinase and its isoenzymes and on glucokinase activity were studied in hepatocarcinogenesis, induced in rats by diethyl nitrosamine. After administration during 7 days of hydrocortisone into normal rats the hexokinase was inactivated by 25% due to decrease in activity of the II isoenzyme. In this case activity of glucokinase was decreased by 38% in young animals and--by 23% in older animals. Insulin, administered within 2 days, caused no effect on the hexokinase activity but the glucokinase was activated by 177%. In hepatocarcinogenesis the effect of hydrocortisone on the hexokinase activity (II isoenzyme) was distinctly decreased and with development of tumors the hormone showed a negligible efficiency. Influence of insulin on the glucokinase activity in hepatocarcinogenesis was similar to the effect found in normal liver tissue.
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PMID:[Sensitivity of hexokinase and glucokinase to hormonal action during hepatocarcinogenesis]. 42 70

Skeletal muscles from 12 male, juvenile-onset diabetics (JD) and 13 nondiabetics (ND) were studied to determine the effects of endurance training on mitochondrial enzyme activities, lipoprotein lipase (LPL) activity, and the oxidation of lipids (14C-palmityl CoA) in vitro. Ten weeks of endurance running (30 min/day, 5 days/wk) resulted in 11.0 and 12.9% gains in aerobic capacity for the JD and ND groups (P greater than 0.05), respectively. Both groups showed significant (P less than 0.05) increases in muscle LPL, carnitine palmityl transferase, succinate dehydrogenase, and hexokinase activities with training. Though the pretraining capacities for 14C-palmityl CoA oxidation were similar for both ND and JD groups, the diabetics showed a 41% greater improvement in the measurement of muscle lipid oxidation after training than did the ND group. The principal finding of this research was that skeletal muscle of juvenile diabetics who are in moderate insulin balance shows adaptations to endurance training that are similar to those of nondiabetic men.
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PMID:Training adaptations in skeletal muscle of juvenile diabetics. 46 7


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