Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Yeast hexokinase A(ATP:D-hexose 6-phosphotransferase) is inactivated when incubated in the presence of xylose and ATPMg, or in the presence of D-lyxose in a reaction medium in which ATPMg is being continuously regenerated (phosphoenolpyruvate and pyruvate kinase). The inactivation is due to the phorphorylation of the protein. A linear relationship was observed between the inactivation and the incorporation of 32P from [gamma-32P] ATP. All hexokinase and ATPase activity of the enzyme is lost when one phosphoryl group is incorporated per enzyme subunit (molecular weight 51,000). The phosphoryl group is covalently bound by a ester linkage with a serine residue of the protein.
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PMID:Studies on the active site of yeast hexokinase. Specific phosphorylation of a serine residue induced by D-xylose and ATPMg. 0 82

In the presence of hexokinase, vesicles derived from the sarcoplasmic reticulum of skeletal muscle are able to accumulate Ca2+ in a medium containing ADP and glucose 6-phosphate. No significant Ca2+ uptake is observed if one of these components is omitted from the assay medium. Due to its high affinity for ATP, the Ca(2+)-ATPase can use the very low concentrations of ATP formed from glucose 6-phosphate and ADP to form a Ca2+ gradient. This finding indicates that glucose 6-phosphate and hexokinase can be used as an ATP-regenerating system. The Ca2+ uptake supported by glucose 6-phosphate and ADP is inhibited by glucose and D-xylose. Half-maximal inhibition is observed in the presence of 0.4 mM glucose and 100 mM D-xylose. The transport ratio (Ca2+ transported:substrate utilized) is the same for glucose 6-phosphate and ATP. The Ca2+ gradient formed when glucose 6-phosphate and ADP are the substrates can be used to synthesize ATP from ADP and Pi. The concentration of ATP formed after reversal of the Ca2+ pump is much higher than that expected from direct equilibration of the reaction between glucose 6-phosphate and ADP.
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PMID:Glucose 6-phosphate and hexokinase can be used as an ATP-regenerating system by the Ca(2+)-ATPase of sarcoplasmic reticulum. 130

Hexokinase is a phosphotransferase that catalyzes phosphoryl transfer from ATP to glucose much more rapidly than the transfer from ATP to water (i.e., hydrolysis). Dimethyl sulfoxide has opposite effects on these two phosphotransferase activities: it enhances ATP hydrolysis and inhibits glucose phosphorylation. Xylose, a sugar that is non-phosphorylatable by hexokinase, enhances ATPase activity which is additive to activation by dimethyl sulfoxide, indicating that the mechanism of activation by dimethyl sulfoxide is different from that of xylose. These results suggest that it is possible to change the specificity of the enzyme in the presence of dimethyl sulfoxide.
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PMID:Effect of dimethyl sulfoxide on phosphoryl transfer catalyzed by yeast hexokinase. 131 74

The intestinal transport of D-xylose was studied during subchronic poisoning of male Wistar rats with the oral administration of potassium nitrate and sodium nitrite. The metabolic parameters of small intestine mucosa were determined one hour after xylose administration, i.e., Na+/K(+)-ATPase, alkaline phosphatase, oxygen consumption, and lactic acid level. Nitrite reduced the absorption of xylose and decreased the activity of Na+/K(+)-ATPase and alkaline phosphatase. No effect of sodium nitrite was demonstrated on the aerobic metabolism of intestinal mucosa with an increased lactic acid level. Potassium nitrate did not effect the processes of intestinal absorption of xylose nor the metabolic parameters of small intestine mucosa.
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PMID:The effect of subchronic poisoning with potassium nitrate and sodium nitrite on the processes of intestinal absorption of D-xylose in rats. 165 32

The intestinal transport of D-xylose was studied during the acute poisoning of male Wistar rats with orally administered potassium nitrate and sodium nitrite. At the peak of xylose absorption, the metabolic parameters of Na+/K(+)-ATPase, alkaline phosphatase, oxygen uptake, and lactic acid level were determined in the small intestine mucosa. Nitrite in a dose of 80 mg NaNO2/kg b.w. increased the permeability of gastric mucosa for D-xylose and raised the uptake of oxygen by the small intestine mucosa. No changes were observed in the activity of Na+/K(+)-ATPase and alkaline phosphatase. A dose of 10 mg NaNO2/kg b.w. was not followed by increased absorption of this sugar. It was also demonstrated that potassium nitrate had no effect on the process of intestinal absorption of D-xylose and failed to change the determined metabolic parameters of the small intestine mucosa.
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PMID:The effect of acute poisoning with potassium nitrate and sodium nitrite on the processes of intestinal absorption of D-xylose in rats. 165 33

The intestinal absorption of D-xylose was studied during the subchronic poisoning of male Wistar rats with orally administered potassium nitrate and sodium nitrite associated with exercise; running on a moving track during the last two weeks of poisoning. The metabolic parameters of Na+/K(+)-ATPase, alkaline phosphatase, oxygen uptake, and lactic acid level in the small intestine mucosa were determined one hour after D-xylose treatment. Exercise increased the toxicity of potassium nitrate and sodium nitrite. The experiment demonstrated post-exercise reduction of D-xylose absorption and decrease activity of Na+/K(+)-ATPase and alkaline phosphatase. Exercise caused transient hypoxia of the small intestine, which was observed only in the groups subjected to exercise on the day of the determinations.
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PMID:The effect of exercise associated with subchronic poisoning with potassium nitrate and sodium nitrite on the processes of intestinal absorption of D-xylose in rats. 165 34

The intestinal absorption of D-xylose was studied during acute poisoning of male Wistar rats receiving intragastrically potassium nitrate and sodium nitrite and small intestine perfusion with these compounds. The metabolic parameters, Na+/K(+)-ATPase, alkaline phosphatase, oxygen uptake, and lactic acid level, were assessed in the small intestine mucosa one hour after administration of these compounds. Exercise was demonstrated to reduce the intestinal absorption of D-xylose, to raise the level of lactic acid, and to increase the oxygen uptake by the small intestine mucosa, but caused no changes in the activity of Na+/K(+)-ATPase or alkaline phosphatase. Also, exercise failed to change the direction of the toxic effects of sodium nitrite but increased potassium nitrate toxicity as evidenced by reduced absorption of D-xylose from the intestine despite lack of changes of the enzymes Na+/K(+)-ATPase and alkaline phosphatase in the mucosa.
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PMID:The effect of exercise associated with acute poisoning with potassium nitrate and sodium nitrite on the processes of intestinal absorption of D-xylose in rats. 165 35

Enprostil is a prostaglandin E2 analogue characterized as a racemic mixture of four stereoisomers. Enprostil and a single isomer, RS-86505-007, were evaluated for their effects on the permeability of actively and passively transported compounds in segments of small intestine from rabbits and monkeys. Consistent with human in-vivo studies, which have demonstrated decreases in absorption of D-xylose, both compounds inhibited D-glucose transport. The passively transported compounds mannitol and progesterone were also less permeable in this model in the presence of enprostil or RS-86505-007. In contrast to the concentration-dependent inhibition displayed by ouabain, RS-86505-007 had no effect on purified Na+K(+)-ATPase. It is suggested that an effect of a general nature, possibly an increase in the barrier properties at the intestinal surface, may explain the transport inhibition. Of two other enprostil isomers, RS-86812-007 inhibited D-glucose transport in rabbit small intestine, while RS-86505-008 had no effect. The prostaglandin E1 analogue misoprostol was ineffective in monkey and poorly effective in rabbit. This suggests that the inhibition of D-glucose transport by enprostil and its active stereoisomers is mediated through some structurally specific receptor interaction.
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PMID:The effects of enprostil and RS-86505-007 on in-vitro intestinal permeability of rabbit and monkey. 196 48

The progression of diabetic nephropathy can be arrested by an improvement in diabetic control. High glucose concentrations increase the flux through the aldose reductase pathway, and it has been proposed that this may contribute to renal damage. Aldose reductase is present in both the glomerulus and the renal tubule. Biochemical changes associated with increased sorbitol production have been demonstrated in animal models, including myo-inositol depletion, reduced Na+-K+ ATPase activity, and activation of the pentose phosphate and glucuronate-xylose pathways. Selective inhibition of aldose reductase reverses these biochemical changes and prevents some of the structural and functional abnormalities in diabetic rats. The potential beneficial effects of aldose reductase inhibitors on diabetic kidney disease in man are at present being investigated.
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PMID:Aldose reductase in the etiology of diabetic complications: 2. Nephropathy. 252 43

Protoplasts of Saccharomyces cerevisiae prepared by snail-gut juice treatment were compared in their transport properties with intact cells. 1. Constitutive monosaccharide transport (D-xylose, 6-deoxy-D-glucose), as well as inducible transport of D-galactose, were unaltered. 2. Phosphorylation-associated transport of 2-deoxy-D-glucose was enhanced in protoplasts, possibly as a consequence of removal of the unstirred layer of the cell wall. 3. Proton-driven transports of trehalose, L-leucine, L-proline and monophosphate could not be activated by preincubation with D-glucose, apparently owing to lack of proton-solute coupling in transport. Utilization of glucose was not depressed but respiration was reduced by about 50% while acidification of the external medium after glucose addition was inhibited by more than 90%. This may be related to the inability of protoplast plasma membrane H-ATPase to be activated by glucose and hence to impaired proton-translocating capacity. Uranyl ions inhibited generally much less in protoplasts than in intact cells although their binding to protoplasts was greater (maximum 0.68 fmol per cell but 3.2 fmol per protoplast).
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PMID:Absence of glucose-stimulated transport in yeast protoplasts. 286 54


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