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)

I have re-examined optimum reaction conditions for measurement of creatine kinase (EC 2.7.3.2). The optimum pH is 6.45, and 2,2-bis(hydroxymethyl)-2,2',2''-nitrotriethanol acetate, 200 mmol/liter, is the buffer of choice. Thioglycerol, 20 mmol/liter, is superior for both in-assay reactivation and for storage stability of sera. Fluoride, 25 mmol/liter, a broad inactivator of adenylate kinase (EC 2.7.4.3), has little effect on creatine kinase and is superior to AMP for adenylate kinase inhibition in the assay of creatine kinase. Magnesium ion, ADP, and buffer concentrations are interdependent and their optima must be determined together. The hexokinase/glucose-6-phosphate dehydrogenase activity ratio should not exceed 1.6. The range of linearity is limited by the glucose-6-phosphate dehydrogenase and NAD+ concentrations. Glucose-6-phosphate dehydrogenase, ADP, and NAD+ are the constituents most likely to result in unacceptable blanks. Creatine kinase is inhibited noncompetitively by anions: acetate and fluoride inhibit slightly, but sulfates, nitrates, and excessive chlorides should be avoided.
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PMID:Creatine kinase: re-examination of optimum reaction conditions. 1 66

Pyrimidine 5'-nucleotidase (P5N, EC 3.1.3.5) appears to be a sensitive index of exposure to low level lead. In 21 children 2 to 5 years old with blood leads of 7 to 80 micrograms/dl there was a negative linear correlation of blood lead and red cell P5N: r = -0.60 (P less than 0.01), Y = -0.11X + 12.3. In rats, the enzyme assay was quantitatively similar to that of the human. A treatment group of 12 rats received lead acetate, 36 mg/kg/day, of lead as 0.17 M lead acetate for 24 days. The blood lead of treated rats increased from the control value of 8.3 +/- 1.3 to 36.0 +/- 0.5 on day 24; P5N decreased from 18.3 +/- 0.8 units to 9.0 +/- 1.0 and was below control values at a blood lead of 25. There was a significant negative linear correlation of blood lead and P5N: r = -0.85; n = 17; P less than 0.001; Y = 0.34X + 20.9 that was independent of the correlationship with the reticulocytes. At these levels of blood lead and P5N there was no significant change in the hexokinase, hemoglobin or red cell count and no evidence of stippling.
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PMID:Low level lead and inhibition of erythrocyte pyrimidine nucleotidase. 23 17

Small angle x-ray scattering measurements on dimeric yeast hexokinase B at pH 5.5 in acetate buffer yield a radius of gyration of 31.28 +/- 0.23 angstrom. This measured value is comparable to the radius of gyration of 31.5 angstrom calculated from the refined coordinates of the dimer in the BII crystal form. The hexokinase dimer found in the BI crystal form has a radius of gyration of 42 angstrom calculated from the atomic coordinates. Thus, the measured radius of gyration is consistent with the BII dimer being the predominant species in solution and rules out the existence of the BI dimer as a major species under these conditions.
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PMID:Small angle X-ray scattering of dimeric yeast hexokinase in solution. 37 85

The correlation between deltamuH, the proton electrochemical potential difference, and the rate of controlled respiration is analyzed. deltamuH (the proton concentration gradient) is measured on the distribution of [3H]acetate, and deltapsi (the membrane potential) on the distribution of 86Rb+, 45Ca2+ and [3H]triphenylmethylphosphonium used either alone or simultaneously. The effects of the addition of ADP + hexokinase (state-3 ADP) and of carbonylcyanide trifluoromethoxyphenylhydrazone (state-3 uncoupler) on respiration and deltamuH are not equivalent: the uncoupler depresses deltamuH more than ADP at equivalent respiratory rates. The effects of the additions of nigericin-valinomycin and of ionophore A23187 (state-3 cation transport) and of carbonylcyanide trifluoromethoxy-phenylhydrazone (state 3-uncoupler) on respiration and deltamuH are also not equivalent: the uncoupler depresses deltamuH more than A23187 and nigericin + valinomycin at equivalent respiratory rate. A23187 is very efficient in stimulating respiration with negligible deltamuH changes.
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PMID:Proton electrochemical gradient and rate of controlled respiration in mitochondria. 62 17

1. The development of the total rat brain creatine kinase was studied in brain homogenates. Until approx. 14-15 days after birth, the activity remains less than one-third that of the adult activity (207+/-6 units/g wet wt. s.d.; n=3). Over the next 10 days the activity increases markedly to the adult value and thereafter remains essentially constant. 2. In the adult brain, approx. 5% (11.9+/-2.2 units/g wet wt. s.d.; n=5) of the total creatine kinase is associated with the mitochondrial fraction. This creatine kinase could not be solubilized by sodium acetate solutions of up to 0.8m concentration, whereas 66% of the hexokinase associated with brain mitochondria was released under these conditions. 3. Rat brain mitochondria incubated in the presence of various concentrations of creatine (1, 5 and 10mm) and ADP (100mum) synthesized phosphocreatine at rates of approx. 4.5, 11 and 17.5nmol/min per mg of mitochondrial protein. Atractyloside (50mum) or oligomycin (1.5mug/mg of mitochondrial protein) completely inhibited the synthesis of phosphocreatine. 4. The apparent K(m) and V(max.) values of the mitochondrially bound rat brain creatine kinase were determined in both directions. The V(max.) in the direction of phosphocreatine synthesis is 237nmol/min per mg of mitochondrial protein, with an apparent K(m) for creatine of 1.67mm and for MgATP(2-) of 0.1mm, and in the reverse direction V(max.) is 489nmol/min per mg of mitochondrial protein, with an apparent K(m) for phosphocreatine of 0.4mm and for MgADP(-) of 27mum. 5. The results are discussed with reference to the role that the mitochondrially bound creatine kinase may play in the development of brain energy metabolism.
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PMID:Studies on the mitochondrially bound form of rat brain creatine kinase. 62 73

A micromethod for the determination of glucose in 20 microliter of capillary blood using glucose dehydrogenase is described. After deproteinisation with uranyl acetate, the samples are analysed by an Autoanalyzer II method or by a manual procedure. Precision and accuracy are well correlated with the hexokinase-glucose-6-phosphate dehydrogenase method. Eleven months experience have shown the practicability and economic advantages of this method.
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PMID:[Microdetermination of glucose using glucose dehydrogenase, with independent sample preparation in the routine laboratory (author's transl)]. 64 49

The free and unprecipitated activity of succindehydrogenase and glucose-6-phosphatase, as well as of that of glucose-6-phosphate-dehydrogenase in the rats liver was determined. The animals received for a long time (1--3 and 6 months) a new organophosphorus pesticide valexon (0.0-diethyl thiophosphoryl-oxyiminophenylnitryle acetate) by mouth in doses of 31 mg/kg and 3.1 mg/kg which corresponds to 1/20 and 1/200 LD50. The earliest changes (after 1 month) include: falling activity of hexokinase and a rise in that of glucose-6-phosphatase and succindehydrogenase, pointing to the damage of microsomes and mitochondria supervenes in 1 and 6 months time after introduction, respectively. The role of an early injury of microsomes and of disturbed first stages of glucose metabolism in the mechanism of the valexon action is suggested.
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PMID:[Activity of the indicator enzymes of liver subcellular structures with the prolonged administration of Valexon]. 71 33

There was a close correlation between the hexokinase-glucose-6-phosphate-dehydrogenase method and reflomat/Reflotest-glucose on capillary blood samples without addition of glycolysis-inhibitors. The relative deviations were less than 10% over the entire range. In systematic studies set up to determine the influence of sodium fluoride and sodium monoiodo-acetate on the reflomat/Reflotest glucose system it was demonstrated that sodium monoiodo-acetate can be used when determining glucose with reflomat/Reflotest glucose, while sodium fluoride produced false values with this system.
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PMID:[Results of using the reflomat for determining glucose concentration, and the influence of glycolysis inhibitors on Reflotest-glucose (author's transl)]. 72 78

Previous reports that rabbit adipose tissue does not synthesize fatty acids at significant rates led us to study in detail the pathways of lipogenesis and glyceroneogenesis in this tissue. We found that rabbit adipose tissue has a low capacity for denovo fatty acid synthesis from glucose but a high capacity for synthesis from pyruvate and acetate. The tissue can also convert pyruvate to glyceride-glycerol via the dicarboxylic acid shuttle and gluconeogenic pathways. Experiments with hydroxycitrate, a potent inhibitor of citrate cleavage enzyme, demonstrated that this is an obligatory enzyme in lipogenesis from pyruvate. The lipogenic system of rabbit adipose tissue resembles that of a ruminant in that it is adapted to utilize acetate rather than glucose. However, in contrast to ruminant tissues, the limited ability to convert glucose to fatty acid results not from a deficiency in the enzymes concerned with the transport of acetyl units out of the mitochondria but from a block prior to the level of pyruvate, most likely at the hexokinase and pyruvate kinase reactions.
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PMID:Lipogenesis in rabbit adipose tissue. 114 72

In the hexokinase isoenzyme pattern on the cellulose acetate membrane electropherogram of the supernatant fraction of Ehrlich ascites tumor cells, a band was detected moving slower than of common Type I isoenzyme. This band was assumed to be due to the presence of a variant of the hexokinase isoenzymes in the cells, since such a band was not detected in the normal tissues, and a change in the intensity of the band in response to a sulfhydryl agent, etc., differed from that of the common Type I and II isoenzymes. The band was also found in AH-7974 and MH-134 ascites tumor cells, in spite of the difference in the species of the tumor-bearing animals and originating tissue.
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PMID:A variant of hexokinase isoenzymes detected in ascites tumor cells. 115 3


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