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)

A congenital erythrocyte pyruvate kinase (PK) deficiency was found in a 72-year old female patient with chronic myelomonocytic leukemia (CMML). Erythrocyte PK deficiency was associated with an increase in the activity of hexokinase, 6-phosphogluconate dehydrogenase and glutathione peroxidase in erythrocytes as well as a decrease in acetylcholinesterase, glutathione reductase and glucosephosphate isomerase activities. The enzymatic abnormalities were accompanied by alterations in hemoglobin and in i antigen content of erythrocyte membrane. In addition, bone marrow ultrastructural studies showed dyshemopoietic changes in all blood cell lines and especially in erythroblasts. The present findings confirm the close relationship between CMML and acquired dyserythropoietic syndromes and constitute a new observation of the infrequent association of hereditary erythrocyte enzymopathies and leukemia. A survey of the literature is presented.
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PMID:Chronic myelomonocytic leukemia associated with hereditary pyruvate kinase deficiency and multiple acquired erythrocyte abnormalities. 10 94

The aluminum present as a contaminant in ATP preparations can cause strong inhibition of yeast hexokinase P-II activity at pH 7.0 or below but has little or no inhibitory effect at a pH of 7.5 or greater. The inhibition is reversed by citrate, 3-phosphoglycerate, malate, phosphate, and catecholamines, all of which have previously been described as activators of hexokinase at low pH. We suggest that these agents activate the enzyme only by virtue of their ability to coordinate with aluminum present in the assay system. The presence of aluminum is also responsible for the "negative cooperativity" observed at low pH with respect to Mg . ATP concentration--i.e., the inhibition by aluminum is uncompetitive at low Mg . ATP concentrations but becomes competitive at high Mg . ATP concentrations. The inhibition is thought to be due to formation of a complex of Al . ATP with the enzyme, with a dissociation constant (Ki) of 0.1 microM. Yeast hexokinase P-I is somewhat less sensitive to A1 than is hexokinase P-II, and yeast glucokinase is not detectably affected. The hexokinase in rat brain (type I) shows a pH-dependent inhibition by Al similar to that observed with the yeast hexokinases, whereas the rat muscle (type II) enzyme is less sensitive, suggesting a possible relationship to aluminum encephalopathy in man.
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PMID:Proton-dependent inhibition of yeast and brain hexokinases by aluminum in ATP preparations. 11 25

In previous papers we reported that the earlier peak time (PT) in radiorespiratory during feeding with 3'-methyl-4-(dimethylamino)azobenzene(3'-Me-DAB) is due to activation of the hexose monophosphate (HMP) pathway together with hepatic cell proliferation reflecting the toxic effects of this carcinogen. In this study, we investigated the correlation between the results of radiorespiratory and the levels of enzyme activities of HMP pathway in regenerating rat liver in connection with hepatic cell proliferation. [3H]Thymidine incorporation into rat liver DNA and the activities of hexokinase (HK) and glucose-6-phosphate dehydrogenase(G-6-PD) reached a maximum at the 3rd day after partial hepatectomy. On radiorespirometry using [U-14C] glucose, the peak time (PT) was much earlier at the 2nd to 3rd day after partial hepatectomy. The peak height (PH) decreased to less than 1/2 of the initial level at the 2nd, but began to recover from the 3rd day. The yield value (YV) remained below the initial level for 4 days after the operation.
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PMID:Radiorespirometric analysis of glucose metabolism in the rat during feeding with 3'-methyl-4-(dimethylamino)azobenzene--radiorespirometry after partial hepatectomy. 12 May 61

The R3230AC mammary adenocarcinoma was not dependent on insulin; tumor growth was equal to or greater in diabetic rats than in intact animals. However, tumor growth was reduced when daily doses of insulin were administered. Treatment with estrogen inhibited growth of the R3230AC carcinoma, either in diabetic rats or in intact animals simultaneously treated with insulin. The effects of insulin plus estrogen treatment appeared to be additive in causing inhibition of tumor growth. Tumors from diabetic rats showed few metabolic alterations as reflected by little or no changes in the activities of selected glycolytic enzymes, pyruvate kinase, phosphofructokinase, and hexokinase, nor any striking changes in the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, representing the pentose phosphate pathway. A modest reduction in the ratio of utilization of (1-14C)glucose: (6-14C)glucose was seen in vitro by tumors from diabetic rats. It was concluded that insulin, along with estrogen and prolactin, should be considered as a hormonal factor that influences growth of this automonous, hormone-responsive adenocarcinoma.
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PMID:Influence of insulin on estrogen-induced responses in the r3230ac mammary carcinoma. 12 68

The metabolic activity of the red cell glycolytic pathway hexose monophosphate shunt (HMP) with dependent glutathione system was studied in patients with hyperthyroidism (n = 10), hyperlipoproteinemia (n = 16), hypoglycemia (n = 25) and hyperglycemia (n = 23). In uncontrolled diabetics and patients with hyperthyroidism the mean value of glucose phosphate isomerase (GPI), glucose-6-phosphate dehydrogenase (G-6-PD), glutathione reductase (GR) was increased, whereas these enzyme activities were reduced in patients with hypoglycemia. Apart from a few values of hexokinase (HK) which were lower than normal the results in hyperlipoproteinemia patients remained essentially unchanged, including the intermediates such as 2,3-diphosphoglycerate (2,3-DPG), adenosine triphosphate (ATP) and reduced glutathione (GSH). While increased rates of 2,3-DPG and ATP in hypoglycemia patients were obtained, these substrates were markedly reduced in diabetics.
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PMID:Adaptation of red cell enzymes and intermediates in metabolic disorders. 12 51

During yeast cultivation the activity of hexokinase and phosphofructokinase, the triggering enzymes of glycolysis, was measured and the total amount of nucleic acids was determined. The impoverished medium--postdistillation molasses residue--was used for yeast generation in the studies. A decline in the enzyme activity was observed, wheras the total amount of nucleic acids remained unaltered. The activity of hexokinase and phosphofructokinase increased significantly when the yeast cultivated on the molasses residue were stimulated by an addition of a small amount of molasses upon low aeration. The measurement of the activity of the above enzymes is a sensitive test and can be recommended for studying the technology of alcohol fermentation.
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PMID:[Enzyme activity of yeasts as an indicator of their physiological state]. 12 55

Cytochalasin A at 10-20 mug/ml inhibits growth and sugar uptake by Saccharomyces strain 1016. The effects of cytochalasin A in intact cells were completely prevented when 1 mM cysteine or dithiothreitol was added along with cytochalasin A, but were not eliminated by thiols added after inhibition had occurred. Purified yeast hexokinase, glucose-6-P dehydrogenase, phosphofructokinase and aldolase were not sensitive to cytochalasin A (20 mug/ml). Glyceraldehyde-3-P dehydrogenase was strongly inhibited by cytochalasin A (5 mug/ml); activity was promptly restored by thiols. Anaerobic glycolysis was inhibited by cytochalasin A or by iodoacetate; unlike iodoacetate, cytochalasin A did not cause accumulation of sugar phosphates. In contrast, cytochalasin A, but not iodoacetate, inhibited isolated membrane-bound ATPases. Cytochalasin A is a sulfhydryl-reactive agent and has membrane-related effects (adenosine triphosphatase) which may well be the basis of its interference with energy-dependent uptake of solutes.
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PMID:Action of cytochalasin A, a sulfhydryl-reactive agent, on sugar metabolism and membrane-bound adenosine triphosphatase of yeast. 12 88

Two reaction intermediates of H-meromyosin (HMM) ATPase [EC 3.6.1.3], E2AT32P, and (see article), were formed by mixing excess HMM with AT32P. Then a large excess of unlabelled ATP was added, and the amount of AT32P liberated from E2AT32P was measured as the difference between the total amount of AT32P in the reaction mixture and the amount of AT32P bound to HMM, obtained by filtering the mixture after adding charcoal to adsorb nucleotides (charcoal-filtration method). The amount of free AT32P was also measured as the amount of glucose-6-32P formed within 15 sec after adding large excesses of hexokinase [EC 2.7.1.1] and glucose to the reaction mixture. The rate constant, k-2, for the step E2ATP yields E plus ATP was calculated at various KCl concentrations from the time-course of liberation of AT32P. The intermediate, (see article), was formed by mixing HMM with AT32P in a molar ratio of 1:2, and the rate constant, k-6, for the step (see article) was also determined by the same procedures used for k-2. In 0.5 M KCl and 2 mM MgCl2 at pH 7.8 and 0 degrees, k-2 and k-6 were 0.002 sec-1 and 0.1 sec-1 or more, respectively. From the rate constants determined in this work and the rate and equilibrium constants which we reported previously, the standard free energy changes (kcal/mole) for formation of various reaction intermediates in the reaction of HMM ATPase in 0.5 M KCl and 2 mM MgCl2 at pH 7.8 and 0 degrees were calculated to be as follows: (see article).
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PMID:Standard free energy changes for formation of various intermediates in the reaction of H-meromyosin ATPase. 12 76

ATP and citrate, the well known inhibitors of phosphofructokinase (ATP: D-fructose 6-phosphate 1-phosphotransferase, EC 2.7.1.11), were found to inhibit the activities of the multiple forms of phosphoglucomutase (alpha-D-glucose 1,6-bisphosphate: alpha-D-glucose 1-phosphate phosphotransferase, EC 2.7.5.1) from rat muscle and adipose tissue. This inhibition could be reversed by an increase in the glucose 1,6-bisphosphate (Glc-1,6-P2) concentration. Other known activators (deinhibitors) of phosphofructokinase, viz. cyclic AMP, AMP, ADP or Pi, had no direct deinhibitory action on the ATP or citrate inhibited multiple phosphoglucomutases. Cyclic AMP and AMP, could however lead indirectly to deinhibition of the phosphoglucomutases, by activating phosphofructokinase which catalyzes the ATP-dependent phosphorylation of glucose 1-phosphate to form Glc-1,6-P2, the la-ter then released the multiple phosphoglucomutases from ATP or citrate inhibition. The Glc-1,6-P2 was also found to exert a selective inhibitory effect on hexokinase (ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1) type II, the predominant form in skeletal muscle. This selective inhibition by Glc-1,6-P2 was demonstrated on the multiple hexokinases which were resolved by cellogel electrophoresis or isolated by chromatography on DEAE-cellulose. Based on the in vitro studies it is suggested that during periods of highly active epinephrine-induced glycogenolysis in muscle, the Glc-1,6-P2, produced by the cyclic AMP-stimulated reaction of phosphofructokinase with glucose 1-phosphate, will release the phosphoglucomutases from ATP or citrate inhibition, and will depress the activity of muscle type II hexokinase.
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PMID:Complementarity in the regulation of phosphoglucomutase, phosphofructokinase and hexokinase; the role of glucose 1,6-bisphosphate. 12 9

The control theory of steady states, previously presented for linear enzymatic systems (Heinrich and Rapoport, 1974) is extended to nonlinear systems. On the basis of three theorems a new procedure for the calculation of the control strength and of the control matrix is developed. The theory is applied to the extended model of glycolysis of erythrocytes, which includes also ATP-consuming processes. Also in this model the glycolytic flux is mainly controlled by the hexokinase-phosphofructokinase-system. The control strengths of the pyruvate kinase and of the enzymes of the 2.3 P2G-bypass are negligibly small. The control strength of the ATPase is negative, i.e. an activation of this enzyme leads to a decrease of the flux. For transition states of multienzyme systems definitions are given for the mean time required for the transition of the metabolites and for the "transient control" of enzymes. Enzymes with a pronounced influence on the transition time are called time-limiting enzymes. Enzymes which excert strong control on the time-dependent processes may have little influence under steady state conditions and vice versa. The transition times of ATP have been calculated for transient states of glycolysis.
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PMID:Mathematical analysis of multienzyme systems. II. Steady state and transient control. 12 16


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