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)

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

Mutants have been isolated in S. cerevisiae with the phenotype of growth on pyruvate but not on glucose, or growth on rich medium with pyruvate but inhibition by glucose. Screening of mutagenized cultures was either without an enrichment step, or after enrichment using the antibiotic netropsin (Young et al. 1976) or inositol starvation (Henry, Donahue and Culbertson 1975). One class of mutants lacked pyruvate kinase (pyk), another class had all the enzymes of glycolysis, and one mutant lacked phosphoglucose isomerase (pgi, Maitra 1971). Partial reversion of pyruvate kinase mutants on rich medium containing glucose gave double mutants now also lacking hexokinase (hxk), phosphofructokinase (fk), or several enzymes of glycolysis (gcr). In diploids the mutations were recessive. pyk, pgi, pfk, and gcr segregated 2:2 from their wild-type alleles. PYK hxk, PYK pfk, and PYK gcr segregrants grew on glucose.
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PMID:Glycolysis mutants in Saccharomyces cerevisiae. 14 95

An ultramicrochemical technique has been adapted to the evolution of enzyme profiles within individual human mammary tumors. Tandem observation of adjacent stained and lyophilized sections permitted dissection of microgram quantities of freeze-dried material within confirmed regions of malignancy. Enzymes frequently monitored to examine glycolytic, respiratory, and metastatic capacity were microanalyzed successfully: lactic dehydrogenase (LDH), phosphoglucose isomerase (PGI), malate dehydrogenase (MDH), acid phosphatase (AP), aldolase (ALD), glucose-6-phosphate dehydrogenase (G6PDH), pyruvate kinase (PK), alpha-glycerophosphate dehydrogenase (alpha-GOPDH), hexokinase (HK), and phosphofructokinase (PRK). All enzyme activities were higher in infiltrating ductal carcinomas than in fibroadenomas. Extracts of tumor cells mixed in varying proportions with brain or muscle extracts of rat evidenced no modification of expected activity. The technical adaptation described provided a sensitive methodology to resolve problems of relication, profile analysis, sample quantity, and selectivity within heterogeneous tissues.
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PMID:Application of a microchemical technique to the elucidation of enzyme activity profiles within single human mammary tumors. 20 41

This paper starts a series on red blood cell (RBC) metabolism in patients with chronic renal failure (CRF). The glycolytic enzyme levels and in vitro half-lives of these patients' RBCs were determined. A number of enzymes (hexokinase, glucose-6-phosphate isomerase, fructose-6-phosphate kinase, aldolase, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase) showed higher activities than in normal control RBCs. Other enzyme activities were normal. These results were discussed and several possible mechanisms considered. We favour the point of view of a shortened life span of the RBCs in CRF, making the most unstable enzymes of the glycolytic sequence appear increase as compared with normal controls.
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PMID:Metabolism of red blood cells in chronic renal failure. I. Glycolytic enzyme levels. 22 98

The denaturation of eight purified yeast enzymes, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, 3-phosphoglycerate kinase, alcohol dehydrogenase, beta-fructosidase, hexokinase and glucose-6-phosphate isomerase, promoted under controlled conditions by the free fatty acids myristic and oleic, is selective. Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1 oxidoreductase, EC 1.1.1.49) is extremely sensitive to destabilization and was studied in greater detail. Results show that chain length and degree of unsaturation of fatty acids are important to their destabilizing effect, and that ligands of the enzyme can afford protection. The denaturation process results in more than one altered form. These results can be viewed in the perspective of the possibility that amphipathic substances, and in particular free fatty acids, may play a role for enzyme degradation in vivo, by initiating steps of selective denaturation.
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PMID:Selective denaturation of several yeast enzymes by free fatty acids. 35 87

A method is described for the measurement of enzyme activity under xeric conditions. The reaction mixtures had water contents ranging between 0.1 and 0.6g/g of reaction mixture. For glucose 6-phosphate dehydrogenase, hexokinase and fumarase, enzyme activity became detectable (about 0.05% of the fully hydrated rate) when the water content was about 0.2g/g of reaction mixture, and for phosphoglucose isomerase, around 0.15g/g of reaction mixture. With the water content raised to 0.3g/g of reaction mixture the reaction rates were only increased to 0.1-3% of the fully hydrated rate. When the combined rates for phosphoglucose isomerase and glucose 6-phosphate dehydrogenase were measured, reasonable agreement was found between the experimental data and those calculated from the individual experimentally determined rates on the assumption that diffusion was not further limiting. A method was devised for measuring the diffusion coefficients of low-molecular-weight substances in solutions having low water contents. The diffusion coefficients of riboflavin in sorbitol solution decreased by about 100-fold when the water content of the latter was reduced from 3 to 0.25g/g of sorbitol. It is concluded that to detect enzyme activity a certain minimal amount of water is required and that above this minimum the rate is still restricted by diffusion limitation. The relevance of the results to the physical state of water in reaction mixtures and to metabolism in seeds and spores in xeric conditions is discussed.
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PMID:The effect of restricted hydration on the rate of reaction of glucose 6-phosphate dehydrogenase, phosphoglucose isomerase, hexokinase and fumarase. 47 53

The ratios of some key enzymatic activities of carbohydrate metabolism have been measured in human tumor cytosols. The activities of whole hexokinase (low Km, EC 2.7.1.1 and high Km, EC 2.7.1.2), 6-phosphogluconate dehydrogenase (EC 1.1.1.43), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and glucose-6-phosphate isomerase (EC 5.3.1.9) change according to a biochemical pattern coherent with cell growth requirements. 6-phosphogluconate dehydrogenase activity was in each sample tested higher than glucose-6-phosphate dehydrogenase activity; this indicates that 6-phosphogluconate, a powerful inhibitor of glucose-6-phosphate isomerase, is unlikely to accumulate and inhibit this enzyme and glucose-6-phosphate channelling into glycolysis.
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PMID:6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, glucose-6-phosphate isomerase, and hexokinase activity ratios in some human tumor cytosols. 74 21

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

1. The effects of protein concentration and ionic strength on the adsorption of the individual glycolytic enzymes to F-actin and F-actin--trypomyosin--troponin have been studied. 2. Appreciable association was demonstrated under conditions of physiological ionic strength and high protein concentration, and tropomyosin--troponin established as an important and generalized component of these interactions. 3. Phosphofructokinase, aldolase, pyruvate kinase, lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphate isomerase were strongly bound under these conditions, while triosephosphate isomerase, phosphoglycerate kinase, phosphoglycerate mutase, enolase and hexokinase displayed less adsorption to the structural proteins. 4. The influence of a number of parameters on the adsorption phenomena was examined. Ca2+ and fructose 1,6-diphosphate increased the adsorption of aldolase, lactate dehydrogenase and pyruvate kinase, while decreasing the adsorption of the enzymes of the constant-proportion group. 5. Of the other major enzymic components of skeletal muscle, creatine kinase, adenylate kinase and malate dehydrogenase showed no adsorption to F-actin--tropomyosin--troponin under the experimental conditions. Some adsorption was evident, however, in the case of aspartate aminotransferase, (NADP) isocitrate dehydrogenase and alpha-glycerolphosphate dehydrogenase. 6. These results have been discussed in relation to their functional significance and the roles of enzyme compartmentation in the cell.
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PMID:On the association of glycolytic enzymes with structural proteins of skeletal muscle. 111 88

In this study we compare the specific activities and isoenzyme patterns of five enzymes--phosphoglucose isomerase, phosphoglucomutase, hexokinase, lactate dehydrogenase, and alkaline phosphatase--in term placenta with the analogous enzymes in a clone of choriocarcinoma cells grown in culture. Phosphoglucose isomerase, phosphoglucomutase, and lactate dehydrogenase specific activities of the choriocarcinoma did not differ by more than two or three times from the mean activities of the comparable enzymes in placenta; the specific activity of hexokinase in the choriocarcinoma amounted to 14 per cent of the mean value for placenta. In contrast, the mean specific activity of heat-stable alkaline phosphatase in the choriocarcinoma amounted to only 1 per cent of the mean value for placenta. By growing the cells in 5-bromodeoxyuridine, 20 mug per milliliter, we were able to increase alkaline phosphatase activity to 68 per cent of the mean value for placenta. For both extracts, phosphoglucose isomerase zymograms were similar and phosphoglucomutase zymograms were similar. The hexokinase zymogram of term placenta showed two isoenzymes which stained more intensely with 0.5 mM. glucose than with 0.1M glucose. A hexokinase isoenzyme was observed in zymograms of both extracts which stained more intensely with 0.1M glucose than with 0.5 mM glucose. Lactate dehydrogenase exhibited an extra isoenzyme in the choriocarcinoma extract. When the cells were cultivated in medium containing 5 mug per milliliter of 5-bromodeoxyuridine, the induced phosphatase in the cell line was electrophoretically similar to placental phosphatase. At higher concentrations of 5-bromodeoxyuridine, the most anodal isoenzyme was 0.5 cm. slower in mobility than the comparable placental isoenzyme.
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PMID:Enzymes of normal and malignant trophoblast: phosphoglucose isomerase, phosphoglucomutase, hexokinase, lactate dehydrogenase, and alkaline phosphatase. 111 69


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