Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The respiration of rabbit heart mitochondria in the presence of ATP is stimulated by ADP, AMP, creatine and glucose plus hexokinase. The values of V for mitochondrial phosphorylating respiration in the presence of corresponding stimulators are equal to 491 +/- 34, 460 +/- 12, 480 +/- 45 and 463 +/- 72 natoms O2 X min-1 X mg-1 of protein, 37 degrees C. The half-maximal stimulation of respiration is observed at 35 microM AMP, 60 microM ADP and 10 mM creatine in the absence of creatine phosphate. In the presence of creatine phosphate the maximal stimulation of heart mitochondrial respiration is achieved under a combined action of creatine and AMP. The inhibition type of mitochondrial respiration by palmitoyl-CoA depends on the nature of stimulators used. Thus, with ADP or glucose plus hexokinase the inhibition is competitive, while with AMP and creatine an uncompetitive and non-competitive inhibition was observed, respectively. The experimental results are indicative of functional coupling of heart mitochondrial adenylate kinase and creatine phosphokinase with ATP-ADP-translocase. It is assumed that creatine and AMP act as physiological regulators of heart mitochondrial respiration ("feed-back" signals from cytoplasm to mitochondria).
 ...
PMID:[Functional coupling of creatine phosphokinase and adenylate kinase with adenine nucleotide translocase and its role in regulation of heart mitochondrial respiration]. 631 78

We measured hexokinase (EC 2.7.1.1) activity in particulate and soluble fractions isolated from bullfrog (Rana catesbeiana) retinas. Seventy-three percent of the hexokinase (HK) activity was associated with the particulate fraction, 27% with the soluble fraction. Both HK fractions could phosphorylate fructose, glucose, 2-deoxy-D-glucose, and mannose, but not galactose. The Km for glucose was 0.14 mM, for 2-deoxy-D-glucose, 3.6 mM. With glucose as substrate, the Vmax for particulate HK was 125-148 microM retina-1 min-1, for soluble HK, 37 microM retina-1 min-1. Product inhibition of particulate HK activity by glucose 6-phosphate was marked, whereas 2-deoxy-D-glucose 6-phosphate did not inhibit the activity. Cyclic AMP stimulated the HK activity of both retinal fractions nearly twofold at concentrations of 0.2-0.8 mM; AMP was much less effective in this regard.
 ...
PMID:Retinal hexokinase: kinetic properties and the effect of cyclic 3',5'-adenosine monophosphate. 631 79

The kinetic properties of rat liver phosphoglycerate kinase were investigated in the forward direction of the reaction (utilization of ADP). The kinetic studies were performed in an assay system using combined hexokinase/glucose-6-phosphate dehydrogenase as an ATP trap. The Km values for Mg ADP1- and 1,3-diphospho-D-glycerate were approximately 0.11 and 0.006 mM, respectively. Reciprocal plots of 1/v versus 1/ (Mg ADP1-) at different fixed concentrations of 1,3-diphospho-D-glycerate and 1/v versus 1/ (1,3-diphospho-D-glycerate) at different fixed concentrations of Mg ADP1- were apparently parallel. However, product inhibition studies (3-phospho-D-glycerate), dead-end inhibition studies (2,3-diphospho-D-glycerate), and adenosine and AMP inhibition patterns yielded results consistent with a rapid equilibrium random mechanism in which the binding of one substrate greatly decreases the affinity of the enzyme for the second substrate. Existence of two sites for 3-phospho-D-glycerate is suggested.
 ...
PMID:Kinetic studies of the reaction mechanism of rat liver phosphoglycerate kinase in the direction of ADP utilization. 640 13

Assay of maximal activities of 11 glycolytic enzymes in cell-free buffalo sperm extracts showed that hexokinase, phosphofructokinase and glyceraldehyde-3-phosphate dehydrogenase had the lowest activities, suggesting regulation of fructolysis at steps catalysed by these enzymes. The ratios of glyceraldehyde-3-phosphate dehydrogenase/phosphofructokinase (0.67) and phosphoglycerate kinase/phosphofructokinase (4.60) are typical of cells exhibiting high Pasteur effect (50% for ejaculated buffalo spermatozoa). The regulatory nature of phosphofructokinase was shown through its modulation by ATP, AMP and inorganic phosphate. The determination of fructolytic intermediates and cofactors and calculation of mass action ratios for each enzymic step revealed that hexokinase, phosphofructokinase, fructose-biphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase catalysed reactions far removed from the equilibrium. A regulatory role by glyceraldehyde-3-phosphate dehydrogenase appeared to be most likely because triosephosphates and inorganic phosphate accumulated more under anaerobic than under aerobic conditions.
 ...
PMID:REgulation of glycolysis/fructolysis in buffalo spermatozoa. 645 53

The role of mitochondrial hexokinase (EC 2.7.1.1.) and mitochondrial ATP synthesis in the utilization of glucose for the support of estrogen biosynthesis was examined in placental mitochondrial preparations supplemented with NADP+, glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 4-androstene-3,17-dione. With 14 mitochondrial preparations, rates of steroid aromatization supported by 100 mM glucose and 20 mM ATP had a mean of 65.7 +/- 7.1 (SD) % of rates achieved with saturating levels of glucose 6-phosphate. ADP, but not AMP, could substitute for ATP in this system. Aromatization supported by glucose and high concentrations of ADP was inhibited by AMP but not by 2,4-dinitrophenol or oligomycin. Glucose also supported mitochondrial aromatization when combined with a respiratory chain-linked metabolic substrate (glycerol 3-phosphate) and a limiting concentration of ADP (2 mM). This support was inhibited by 2,4-dinitrophenol, the p-trifluoromethoxyphenylhydrazone of carbonyl cyanide, oligomycin and atractyloside. Thus, glucose metabolism by mitochondrial hexokinase, utilizing ATP generated either by oxidative phosphorylation or mitochondrial adenylate kinase (EC 2.7.4.3), can be coupled with a soluble NADPH-generating system to provide effective support of mitochondrial estrogen synthesis.
 ...
PMID:The support of steroid aromatization by mitochondrial metabolic activities of the human placenta. 670 59

AMP is converted to ATP by incubating overnight with pyruvate kinase, phosphoenolpyruvate and adenylate kinase in the presence of endogenous ATP (ADP) as primer. In a subsequent incubation in the presence of pyruvate kinase, phosphoenolpyruvate, radioactive glucose and hexokinase, ATP and ADP are estimated together by coupling their recycling to the formation of glucose 6-phosphate. The latter is separated by precipitation using 76% (v/v) acetone for radioactivity measurement in the same Eppendorf tube. The sensitivity of these simple procedures matches or exceeds those of luciferase methods of nucleotide determination.
 ...
PMID:Radioisotopic assay of femtomole quantities of total adenine nucleotides, ATP plus ADP, and AMP. 673 60

1. In vitro glucose uptake and glycogen utilization by Hymenolepis microstoma decreased under high oxygen concentrations. 2. 5-Hydroxytryptamine did not stimulate in vitro glucose uptake but did increase glycogen utilizations by H. microstoma. 3. The reduced glucose uptake under high oxygen concentrations (21 and 95%) resulted in a reduction in excretory products. 4. 14CO2-incorporation studies confirmed that, under both 95% O2:5% CO2 and air-minus-CO2 (identical to 21% O2). CO2-fixation by phosphoenolpyruvate carboxykinase (EC 4.1.1.32) was inhibited. 5. The specific activity of hexokinase (EC 2.7.1.1), phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40) was not stimulated by 5-HT. 6. The concentration of ATP required for optimal stimulation of phosphofructokinase activity was 0.67 mM. Activity was further significantly increased by the addition of cAMP and even greater by AMP.
 ...
PMID:5-hydroxytryptamine, glucose uptake, glycogen utilization and carbon dioxide fixation in Hymenolepis microstoma (Cestoda). 681 65

The interactions of ATP and AMP 4-(N-2-chloroethyl-N-methylamino)-benzylamidates with yeast hexokinase were studied. It was found that the ATP analog does not interact with hexokinase. The AMP analog irreversibly and almost completely inactivates hexokinse. A strong protective effect is exerted by MgATP. The value of apparent Ki for the AMP analog is equal to 2.10(4) M. The existence of affinity modification is postulated.
 ...
PMID:[Interactions of yeast hexokinase with ATP and AMP 4-(N-2-chloroethyl-N-methylamino)benzylamidates]. 701 27

With few exceptions, the specific activities of the glycolytic enzymes and the steady-state content of glycolytic and associated intermediates in protoscoleces of the horse (E.g.H) and sheep (E.g.S) strains of Echinococcus granulosus and the closely related E. multilocularis (E.m.) are very similar. Phosphorylase, hexokinase, phosphofructokinase and pyruvate kinase catalyse non-equilibrium reactions and the patterns of activity for pyruvate kinase, phosphoenolypyruvate carboxykinase and malic enzyme are similar in the three organisms. The levels of tricarboxylic acid cycle intermediates in E.g.H., E.g.S. and E.m. are of the same order as those reported in tissues with an active cycle. Each has a complete sequence of cycle enzymes but there are substantial differences between the three parasites with regard to the activity of individual enzymes. The activities of NAD and NADP-linked isocitrate dehydrogenases are significantly lower in E.g.H. than in E.g.S. and particularly in E.m. which suggests that the tricarboxylic acid cycle may play a more important role in carbohydrate metabolism and energy production in the latter parasites. Nevertheless, the three organisms utilize fermentative pathways for alternative energy production, fix carbon dioxide via phosphoenolpyruvate carboxykinase and have a partial reversed tricarboxylic acid cycle. It is speculated that in vivo more carbon will be channelled towards oxaloacetate than pyruvate at the phosphonenolpyruvate branch point. The steady state content of ATP and the ATP/AMP ratios are low in the three organisms, suggesting a low rate of ATP utilization in each.
 ...
PMID:Intermediary carbohydrate metabolism in protoscoleces of Echinococcus granulosus (horse and sheep strains) and E. multilocularis. 707 Aug 45

Regulation of glucose metabolism in glycolysis by round spermatids was studied. Assay of activities of 11 glycolytic enzymes in cell-free spermatid extracts showed that hexokinase, phosphofructokinase, and glyceraldehyde-3-phosphate dehydrogenase had the lowest activities. When the cells were incubated with glucose (10 mM), the intracellular level of ATP fell rapidly and 5'-AMP increased. The ADP level remained unchanged. During incubation with glucose, fructose-1,6-bisphosphate, dihydroxyacetone phosphate, and glyceraldehyde-3-phosphate were accumulated without any change in a mass action ratio of fructose bisphosphate aldolase. Glyceraldehyde-3-phosphate dehydrogenase appeared to play a regulatory role in glycolysis. Glyceraldehyde-3-phosphate dehydrogenase was inhibited by the following compounds (Ki values in parentheses): adenosine (4.34 mM), 5'-AMP (3.50 mM), ADP (2.35 mM), ATP (5.34 mM), and 3',5'-cAMP (0.60 mM). In each case, the inhibition was competitive with NAD (Km = 0.20 mM). The 2'-hydroxy group of the adenine-linked ribose moiety was essential for binding. The compounds adenine, 2'-deoxyadenosine, 2'-AMP, 3'-AMP, CTP, GTP, UTP, and NADP showed little inhibition. These findings suggest that regulation of glycolysis in round spermatids by glyceraldehyde-3-phosphate dehydrogenase is most likely and that glyceraldehyde-3-phosphate dehydrogenase is inhibited by the adenine nucleotides, particularly by 5'-AMP and ADP as inhibitors competitive with NAD.
 ...
PMID:Regulation of glucose metabolism by adenine nucleotides in round spermatids from rat testes. 714 87


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>