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 time course of the rate of the glycolysis of human erythrocytes and of some metabolites were determined before and after rapid deoxygenation at constant intracellular pH. For this purpose stripped deoxygenated haemoglobin was used as a rapid oxygen acceptor. Deoxygenation causes an increase of the glycolytic rate by 26%. Glucose 6-phosphate is decreased while the adenine nucleotides and 2,3-bisphosphoglycerate remain constant. Fructose 1,6-bisphosphate and the triose phosphates decrease transiently before rising. The data can be explained by increased binding of phosphocompounds to deoxygenated as compared with oxygenated haemoglobin. Thereby the control enzymes hexokinase and phosphofructokinase are influenced. It is concluded that under physiological conditions changes in the oxygenation state of haemoglobin per se alter the glycolytic rate.
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PMID:Response of the glycolysis of human erythrocytes to the transition from the oxygenated to the deoxygenated state at constant intracellular pH. 0 13

Measurements are reported on certain isotopic fluxes during the net conversion of glutamine, ADP and Pi to glutamate, NH3, and ATP by Escherichia coli glutamine synthetase (adenylylated form, Mn2+ activated) in presence of a hexokinase/glucose trap to remove the ATP formed during the reaction. The results show that the transfer of oxygens from Pi to glutamine is the most rapid of the measured isotopic interchanges, over five oxygens from Pi being transferred to glutamine for each glutamate formed by net reaction. Under similar conditions, the oxygen transfer from Pi to glutamate, was stimulated somewhat by an increase in the glutamate concentration but inhibited by an increase in the ammonia concentration. The enzyme from brain or peas did not show the rapid transfer of 18O from Pi to glutamine shown by the E. coli enzyme. Deductions are also made from the data about the availability of the oxygens of gamma-carboxyl of bound glutamate for reaction. The most logical explanation of the results with the E. coli enzyme is that the gamma-carboxyl group of bound glutamate has sufficient rotational freedom so that under conditions of rapid substrate interconversion either carboxylate oxygen can participate in the reaction. The results with the pea enzyme are consistent with hindered rotation of the gamma-care additional findings make likely a relative order of certain catalytic steps for the E. coli enzyme as follows: ATP release less than NH3 release less than glutamate release less than substrate interconversion less than glutamine release and Pi release and glutamate release less than ADP release.
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PMID:Rapid transfer of oxygens from inorganic phosphate to glutamine catalyzed by Escherichia coli glutamine synthetase. 0 91

Small-bore ("Autozyme") tubes with immobilized enzymes at the inner wall have been developed and studied for application in the Technicon "SMAC" high-speed continuous-flow biochemical analyzer. Tubes coated with glucose oxidase (D-glucose:oxygen oxidoreductase, EC 1.1.3.4) have been prepared for the assay of glucose, with colorimetric assay of the hydrogen peroxide produced; tubes coated with glycerol kinase (ATP:glycerol phosphotransferase, EC 2.7.1.30) for the enzymatic assay of triglycerides; tubes coated with hexokinase (ATP:D-hexose-6-phosphotransferase, EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NAD+ oxidoreductase EC 1.1.1.49) for the measurement of ATP, an intermediate product in assays for creatine kinase. With use of 10-15 cm lengths of Autozyme tube and SMAC hydraulics (150 samples per hour), assay sensitivity and carryover were similar to values for the corresponding free-enzyme methods. These immobilized enzymes were sufficiently stable for one to eight weeks of continuous use before replacemnt. We conclude that suitable bound-enzyme tubes can replace either single or multiple free-enzyme reagents in many continuous-flow assays at high sampling rates.
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PMID:Continuous-flow analysis for glucose, triglycerides, and ATP with immobilized enzymes in tubular form. 1 65

The interconnections between EEG, intermediary and energy metabolism of the brain cortex and CSF potassium level are studied during severe hypercapnia in anaesthetized, artificially ventilated cats. Hypercapnic animals were ventilated with 40 to 50% to CO2 in oxygen. During severe hypercapnia the EEG becomes isoelectric. The CSF potassium concentration is raised and the changes in metabolism suggest an acidosis-induced inhibition of phosphofructokinase and, probably, of hexokinase. The energy charge potential remains unchanged whereas the cortical ATP concentration increases slightly. It is assumed that the changes in P-creatine and creatine levels are related to the pH-dependency of creatine phosphokinase. Recovery animals were ventilated with 40% CO2 in O2 and subsequently with room air. After termination of CO2 inhalation the EEG reappears, the CSF potassium concentration normalizes, and the inhibition of the glycolytic enzymes disappears. The energy charge potential shows a small decrease. It is not possible to trace back the disappearance of the EEG to only one of the recorded parameters. Cortical P-creatine levels, CSF potassium concentration, changes in membrane permeability and cortical amino acid concentrations are considered in this context.
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PMID:Influence of severe hypercapnia upon cerebral cortical metabolism, CSF electrolyte concentrations and EEG in the cat. 13 59

A study of post-mortem changes in human central nervous tissue has shown that within 100 h of death, no significant change occurs in the amount of nerve cell DNA and nucleolar RNA nor in some membrane-associated enzymes such as succinate dehydrogenase, NADH and NADPH diaphorase, and cytochrome oxidase. Low molecular weight RNA species, probably transfer and messenger RNA are quickly lost, but there is little alteration in ribosomal RNA content. Cytoplasmic enzymes show variable changes; phosphofructokinase activity is rapidly decreased; hexokinase is unaltered but lactate dehydrogenase, pyruvate kinase and glucose-6-phosphate dehydrogenase initially show increases in activity which subsequently decline. Oxygen uptake diminishes quickly. These findings indicate that mechanical alterations in cell structure, following death, render organelles physiologically ineffective long before any significant changes in certain constituent biochemicals are detected. This report emphasizes the great importance necessary in the selection of appropriately time matched post-mortem tissues if accurate comparative studies of many of the cells constituents are to be made.
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PMID:Post-mortem changes in human central nervous tissue and the effects on quantitation of nucleic acids and enzymes. 14 55

The growth of Brucella abortus (US-19) in a complex tryptose-yeast extract medium containing D-glucose is inhibited by 10 mM erythritol. The enzymes of the erythritol pathway, except for D-erythrulose 1-phosphate dehydrogenase (D-glycero-2-tetrulose 1-phosphate:nicotinamide adenine dinucleotide (NAD+) 4-oxidoreductase) were detected in the soluble and membrane fractions of cell extracts. Glucose catabolism by cell extracts was inhibited by erythritol, whereas, phosphorylated intermediates of the hexose monophosphate pathway were converted to pyruvic acid with oxygen consumption. Erythritol kinase (EC 2.7.1.27; adenosine 5'-triphosphate (ATP): erythritol 1-phosphotransferase) was found to be eightfold higher in activity than the hexokinase in cell extracts. In vivo, ATP is apparently consumed with the accumulation of D-erythrulose 1-phosphate (D-glycero-2-tetrulose 1-phosphate) and no substrate level phosphorylation. ATP levels dropped 10-fold in 30 min after addition of erythritol to log phase cells in tryptose-yeast extract medium with D-glucose as the carbon source. These data suggest bacteriostasis in the presence of erythritol results from the ATP drain caused by erythritol kinase.
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PMID:Inhibition of growth by erythritol catabolism in Brucella abortus. 17 Feb 49

A cross-sectional study was carried out to examine the activities of certain enzymes representing aerobic and anaerobic energy metabolism as well as the biosynthesis of collagen of M. vastus lateralis in 23 male endurance athletes in habitual training, aged 33 to 70 years. 23 sedentary healthy men of corresponding ages were selected for the control group. The mean maximal oxygen uptake of the trained subjects was 53.6 ml-kg--1. min--1 and that of the control subjects 36.3 ml-kg--1. min--1. As compared to the control group the trained subjects had significantly higher values in the muscle malate dehydrogenase, succinate dehydrogenase and prolyl hydroxylase activities, whereas the opposite was true in the activity of lactate dehydrogenase. In hexokinase and creatine phosphokinase no marked differences between the groups were observed. The results showed that endurance training leads to increased activities of oxidative enzymes in the skeletal muscle. The adaptation changes were also observed in old men. The increased activity of prolyl hydroxylase may reflect the general enzymatic adaptation to physical training. A possibility exists that the turnover of muscle collagen in endurance athelets is continuously faster than that in sedentary men of corresponding ages.
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PMID:Enzyme activities in muscle and connective tissue of M. Vastus lateralis in habitually training and sedentary 33 to 70-year-old men. 17 30

Some factors that influence the values of respiratory activities of liver mitochondria isolated from surgical biopsy specimens have been studied. By sedimentating of mitochondria at a lower centrifugal force (5,500 g) than usually used for rat liver mitochondria, and washing the mitochondrial pellet twice, the contamination with lysosomes and microsomes was lowered. At 37 degrees C, and in the presence of hexokinase and glucose, the oxygen uptake was greater than at 25 degrees C and in their absence. The respiratory control was good and the respiratory activities were rather stable during the first 3-4 h after isolation. The respiratory activities of mitochondria isolated from patients with duodenal or gastric ulcers, biliary diseases, and subjects with no digestive diseases (all having normal liver) were compared. Differences in oxygen uptake and acceptor control index values with some substrates were noted. The conditions for selection of controls in studies on subcellular fractions of human liver include: absence of any hepatic antecedents; no clinical evidence of liver involvement; no abnormality in routine liver function tests; a histologic aspect free of pathological conditions, and a normal aspect of the tissue during the homogenization and the fractionation procedure (absence of steatosis or fibrosis). These data provide a basis for the standardization of methods in establishing the reference values of mitochondrial activities for the modifications in a variety of diseases.
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PMID:Factors influencing the establishment of the normal values of the respiratory activities of human liver mitochondria. 17 6

The effect of cooling and subsequent rewarming on the tissue respiration of canine hearts was studied during polycomponent ether-oxygen anaesthesia. The tests included the determinations of the activity of the dehydrogenases of the cytrate cycle, the content and activity of chromoproteids, the respiration rate of the mitochondrias on succinate, glutamate and ketoglutarate, the content of glycogen, the activity of the phosphorylases, hexokinase, lactate dehydrogenase, the content of lactate, pyruvate, adenyl nucleotides and creatine phosphate. Significant changes were noted in the content and activity of the above substances, acceleration of mitochondrial respiration, reduced energy regulation of respiration, and decreased amount of the adenyl components. It is suggested that under artificial hypothermia the processes of chromoproteids biosynthesis are enhanced, which results in an increased power of terminal respiration, and conformational rearaangements of the enzymes connected with the membranes occur.
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PMID:[Characteristics of energy metabolism in the myocardium under artificial hypothermia]. 19 79

On aerobic incubation of rat cerebral cortex slices with anomers of D-glucose and with 2-deoxy-D-glucose (2DG) for 5 min, the disappearance of beta-D-glucose from the incubation mixture was greater than that of alpha-D-glucose and both anomers had a greater rate of disappearance than that of 2DG. In addition, there were significantly greater consumption of oxygen and production of lactate with the beta-anomer than with the alpha-anomer. In similar experiments with 3H-labeled D-glucose anomers and [1-3H]-3-O-methyl-D-glucose (3MG), the accumulation of [1-3H]-beta-D-glucose (up to 5 min) by rat cerebral cortex slices was greater than that of [1-3H]-alpha-D-glucose. Although initially lower than that of the anomers, the accumulation of [1-3H]-3MG increased at a greater rate and, by 5 min of incubation, was greater than that of both glucose anomers. This preferential accumulation was seen to disappear when the slices were preincubated with 2DG (hexokinase inhibitor) or when the temperature of incubation was reduced to 20 degrees C. Under those conditions the data with the glucose anomers were similar to those obtained with 3MG. Our data then suggested that the greater accumulation of beta-D-glucose than of alpha-D-glucose by the slices was probably not due to differences in transport through brain cell membranes but rather to the preferential metabolism of the beta-D-glucose.
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PMID:Anomeric preferences of D-glucose uptake and utilization by cerebral cortex slices of rats. 22 92


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