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 purification is described of rat hepatic hexokinase type III and kidney hexokinase type I on a large scale by using a combination of conventional and affinity techniques similar to those previously used for the purification of rat hepatic glucokinase [Holroyde, Allen, Storer, Warsy, Chesher, Trayer, Cornish-Bowden & Walker (1976) Biochem. J. 153, 363-373] and muscle hexokinase type II [Holroyde & Trayer (1976) FEBS Lett. 62, 215-219]. The key to each purification was the use of a Sepharose-N-aminoacylglucosamine affinity matrix in which a high degree of specificity for a particular hexokinase isoenzyme could be introduced by either varying the length of the aminoacyl spacer and/or varying the ligand concentration coupled to the gel. This was predicted from a study of the free solution kinetic properties of the various N-aminoacylglucosamine derivatives used (N-aminopropionyl, N-aminobutyryl, N-aminohexanoyl and N-aminooctanoyl), synthesized as described by Holroyde, Chesher, Trayer & Walker [(1976) Biochem. J. 153, 351-361]. All derivatives were competitive inhibitors, with respect to glucose, of the hexokinase reaction, and there was a direct correlation between the Ki for a particular derivative and its ability to act as an affinity matrix when immobilized to CNBr-activated Sepharose 4B. Muscle hexokinase type II could be chromatographed on the Sepharose conjugates of all four N-aminoacylglucosamine derivatives, although the N-aminohexanoylglucosamine derivative proved best. This same derivative was readily able to bind hepatic glucokinase and hexokinase type III, but Sepharose-N-amino-octanoyl-glucosamine was better for these enzymes and was the only derivative capable of binding kidney hexokinase type I efficiently. Separate studies with yeast hexokinase showed that again only the Sepharose-N-amino-octanoylglucosamine was capable of acting as an efficient affinity matrix for this enzyme. Implications of these studies in our understanding of affinity-chromatography operation are discussed.
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PMID:Purification of the hexokinases by affinity chromatography on sepharose-N-aminoacylglucosamine derivates. Design of affinity matrices from free solution kinetics. 36 63

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

Kinetic and structural studies have been carried out of two isoenzymes of hexokinase from the rat, hexokinase II and glucokinase. Although both enzymes are monomeric, hexokinase II has a molecular weight double that of glucokinase and resembles a dimer of glucokinase. The co-operativity of glucokinase, which is not observed for hexokinase II, appears to be kinetic in origin rather than the consequence of ineractions between distinct glucose-binding sites.
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PMID:Mammalian hexokinases: a system for the study of co-operativity in monomeric enzymes. 55 44

Streptozotocin treatment (125 mg/kg) in the Chinese hamster induced hyperglycaemia, hypoinsulinaemia, hyperglucagonaemia and changes in body, liver, pancreas, stomach, kidney and adipose tissue weights. The pancreatic reserves of insulin and glucagon in the diabetic animals were low, but stomach glucagon high. These animals showed high levels of phosphoenolpyruvate carboxykinase and low levels of glucokinase, hexokinase, isocitrate dehydrogenase and malic enzyme, but normal levels of pyruvate kinase in the liver. Increases in lactate dehydrogenase subunit B and isozymes 2, 3 and 4 were also observed in the liver, but not in the epididymal fat pad, of the diabetic animals. N-Acetyl-beta-D-glucosaminidase was elevated in plasma, liver and heart, but not in the kidney of the treated animals. Renal alpha-galactosidase and beta-glucosidase were depressed, whereas beta-galactosidase and alpha-glucosidase remained essentially normal. These features indicated that there were considerable differences between the biochemical disorders associated with streptozotocin-diabetes in the Chinese hamster and the published observations in the rat.
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PMID:Streptozotocin-induced diabetes in the Chinese hamster. Biochemical and endocrine disorders. 59 Jun 51

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

The D-glucose anomeric preference of hexokinases isolated from rat liver, brain, and skeletal muscle, and bovine retina was studied using the glucose-6-phosphate dehydrogenase-NADP system. The ratios of maximum phosphorylation rates of beta-D-glucose to those of alpha-D-glucose were 1.33, 1.46, and 1.54 for hexokinase types I, II, and III from rat liver, 1.45 and 1.63 for type I from rat brain and bovine retina, 1.53 for type II from rat skeletal muscle, and 0.55 (when determined at 5 mM) for type IV (glucokinase) from rat liver, respectively.
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PMID:D-Glucose anomeric preference of hexokinases in higher animals. 71 11

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

Three glucose-phosphorylating enzymes having different specificities for glucose and fructose were separated from the cell-free extract of Candida tropicalis by means of ammonium sulfate fractionation and chromatography on DEAE-cellulose and Sephadex G-100. Two of them, which phosphorylated fructose 1.5 times faster than glucose, were designated as hexokinase I and II (ATP : D-hexose 6-phosphotransferase, EC 2.7.1.1.), and the other with very low or no fructose-phosphorylating activity, as glucokinase (ATP : D-glucose 6-phosphotransferase, EC 2.7.1.2). Km values for glucose with both hexokinase I and glucokinase were 0.3 mM, and that for fructose with hexokinase I was 2.2 mM. Time-course changes in the levels of these enzymes in C. tropicalis growing on glucose and on n-alkane revealed that hexokinase was induced specifically by the sugars, while glucokinase was a constitutive enzyme. Addition of cycloheximide to the culture medium prevented the increase in the hexose-phosphorylating activity and in the Fru/Glu ratio (the ratio of enzymatic phosphorylation of fructose to that of glucose) in the cells. Although Candida lipolytica also contained hexokinase and glucokinase, both enzymes seemed to be constitutive.
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PMID:Glucose-phosphorylating enzymes of Candida yeasts and their regulation in vivo. 83 48

The authors investigated the in vitro functional differentiation of fetal mouse liver cultured in Rose's circumfusion system with the use of two biochemical markers: The analysis of the inductive response of key enzymes in carbohydrate metabolism to insulin, and the analysis of the liver-specific isozyme of pyruvate kinase [EC 2.7.1.40]. The glucokinase [EC 2.7.1.2] activity, which is only found in mammalian adult liver, emerged on cultivation of 2-3 days and reached a maximum level equivalent to one-half of the adult level. Two- or 3-fold increases in the glucokinase, pyruvate kinase, and glucose-6-phosphate dehydrogenase [EC 1.1.1.49] were induced by a single dose of insulin in fetal liver after 12 days of cultivaton. Hexokinase [EC 2.7.1.1] activity was barely influenced by insulin. These results suggested that fetal mouse liver cultured in this system for 2 weeks maintained the same response to insulin as in vivo adult mouse liver. The pyruvate kinase isozyme patterns of mouse livers in various developmental stages and of cultured fetal mouse liver in the present system were investigated by isoelectric fractionation. The pyruvate kinase isozymes having the highest relative activity were the pI-5.5 isozyme for the adult liver and the pI-6.5 isozyme for 13- to 14-day-old fetal liver. As development in vivo proceeded, a gradual change in isozyme pattern occurred; this consisted of a progressive decrease of the pI-6.5 pyruvate kinase isozyme, "fetal type," in favor of the pI-5.5 isozyme, "adult type." The pyruvate kinase isozyme pattern in 13- to 14-day fetal liver cultured in the system for 2 weeks was similar to that found in adult liver. Thus, it was shown that "fetal type" pyruvate kinase was also replaced by "adult type" pyruvate kinase in vitro. It can be concluded from these findings that fetal mouseliver cultured in the circumfusion system for 2 weeks maintains its functional and morphological identitites as it differentiates toward the adult liver.
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PMID:Functional differentiation of mouse fetal liver in circumfusion system cultures. 93 74

Bilateral subdiaphragmatic vagotomy resulted in a significant decrease of hexokinase, glucokinase, glucose-6-phosphoric and 6 phospho-gluconic dehydrogenases, and lactic dehydrogenase activity in the soluble fraction of rat liver. Blood sugar remained unchanged at all the postoperative periods. It is suggested that the above-mentioned alterations in the enzyme activity were caused by the absence of parasympathetic impulses to hepatocytes.
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PMID:[Effect of bilateral subdiaphragmatic vagotomy on the activity of several energy metabolism enzymes in the liver]. 95 39


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