Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Hexokinase, glucokinase, and phosphofructokinase activity in supernatant hepatic fluid obtained by centrifugation of the homogenate at 20,000 g for 20 minutes was studied during the development of experimental necrosis of the heart muscle. The activity of these enzymes was lowest in the 12th and 24th hour following arterial occlusion. Phosphofructokinase and glucokinase activity returned to the initial level on the 6th and 9th days, respectively; hexokinase activity was still diminished after the 12th day.
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PMID:[Activity of key enzymes of glycolysis in the rat liver during the development of experimental myocardial necrosis]. 14 17

The possible presence of hexokinase in basal lateral membranes from rat kidney proximal tubules was investigated. Basal lateral membranes were obtained from homogenates of rat kidney cortex by differential centrifugation and free flow electrophoresis. They were further purified by density gradient centrifugation. Hexokinase activity was measured as the phosphorylation of D-[U14C]glucose. Throughout the purification of the membranes, the specific activity of hexokinase decreased while that of (Na+ + K+)-ATPase increased. Hexokinase activity in all fractions could be quantitatively accounted for in terms of cytosolic and mitochondrial enzyme contributions. It is concluded that there is no hexokinase activity in basal lateral membranes from rat kidney.
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PMID:Is hexokinase present in the basal lateral membranes of rat kidney proximal tubular epithelial cells? 14 9

The investigations carried out have shown that not only AMP but ADP also undergoes direct deamination in both soluble and mitochondrial fractions of rat brain tissue. Deamination of AMP is stimulated by the addition of ATP and the activity of one of the isoenzymes of AMP-aminohydrolase is markedly enhanced by both yeast and brain hexokinase. Activation by hexokinase is mainly due to its SH groups, through which hexokinase reacts with AMP-aminohydrolase, forming, probably, a protein-protein complex in which AMP aminohydrolase activity is considerably increased. Hexokinase does not affect the deamination of ADP and NAD. Further experiments are needed to find out whether the activation of AMP-aminohydrolase is accomplished by hexokinase itself or by an other protein contaminating it. Deamination of NAD, in contrast to AMP and ADP, takes place only in mitochondria and does not occur in the soluble fraction. In mitochondria besides deamination, AMP and ADP undergo intensive dephosphorylation, while the deamination of NAD is not accompanied by an increase of phosphate, i. e. mitochondria lack enzymes which breakdown NAD to mono nucleotides. Our data indicate that the formation of deamino -NAD from NAD and reamination of deamino-NAD by aspartate to NAD by the formation of intermediary NAD-succinate is of greater importance. The formation of the latter and that of deamino-NAD from NAD as well as the presence of preformed deamino-NAD in mitochondria have been demonstrated by Movsessian. The occurrence of these processes in mitochondria and their role in the formation of ammonia from amino acids is of importance in as much as oxaloacetate formation and its conversion to aspartate, which is necessary for the reamination of deamino-NAD, are localized in mitochondria. The main source of the amino nitrogen of aspartate is known to be glutamate, which incorporates the amino nitrogen of most amino acids. alpha-Keto-glutarate, which is necessary for the synthesis of glutamate, is also formed in mitochondria are the most favourable site for the formation of ammonia from amino acids with the participation of pyridine nucleotides. Of the purine mono and dinucleotides studied deamino-NAD is most effective in the formation of ammonia from amino acids in mitochondria since in contrast to purine mono nucleotides, deamino-NAD and NAD are not dephosphorylated in mitochondria. According to some authors the reamination of IMP by aspartate is of importance in the formation of ammonia from amino acids in brain tissue. In our studies, however, IMP was not effective in the formation of ammonia from aspartate in mitochondrial fractions. IDP was found to be more effective. IMP and IDP may probably participate in the formation of ammonia in the soluble fraction, where nucleotidase activity is considerably low.
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PMID:[Role of adenine mono- and dinucleotides in ammonia formation in brain tissue]. 18 42

Hexokinase activity was detected in cytosols and homogenates from different developmental stages of Bufo bufo embryos starting from stage 17. Free glucose was measured in the embryo cytosol and was detected at each stage tested. At stage 15, a large increase of glucose content of the embryo cytosol occurs. Hexokinase expression in the embryo thus occurs after the increase of cytosol glucose content occurring at stage 15. The findings rule out that glucose by itself is the hexokinase inducer in vivo. The very low glucose utilization found by many authors during early amphibian development may be related to the late hexokinase expression during Bufo bufo development.
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PMID:Late hexokinase activity expression during Bufo bufo development. 40 52

Brain hexokinase (ATP:D-hexose-6-phosphotransferase, EC 2.7.1.1) binds selectively to the outer membrane of rat liver mitochondria but not to inner mitochondrial or microsomal membranes nor to the plasma membrane of human erythrocytes. A protein having subunit molecular weight of 31,000, determined by sodium dodecyl sulfate-gel electrophoresis, has been highly purified from the outer mitochondrial membrane by repetitive solubilization with octyl-beta-D-glucopyranoside followed by reconstitution into membranous vesicles when the detergent is removed by dialysis. When incorporated into lipid vesicles, the protein confers the ability to bind brain hexokinase in a Glc-6-P-sensitive manner as is seen with the intact outer mitochondrial membrane. Hexokinase binding ability and the 31,000 subunit molecular weight protein co-sediment during sucrose density gradient centrifugation. Both hexokinase binding ability and the 31,000 subunit molecular weight protein are resistant to protease treatment of the intact outer mitochondrial membrane while other membrane proteins are extensively degraded. It is concluded that this protein, designated the hexokinase-binding protein (HBP), is an integral membrane protein responsible for the selective binding of hexokinase by the outer mitochondrial membrane.
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PMID:Purification of a hexokinase-binding protein from the outer mitochondrial membrane. 44 25

Recent evidence has suggested a role for the polyol pathway in pathogenesis of cell damage in diabetes Glucose may be phosphorylated to glucose-6-phosphate via hexokinase and enter glycolysis or reduced to sorbitol via aldose reductase to enter the polyol pathway. The poorly diffusible sorbitol is converted via sorbitol dehydrogenase to fructose. Hexokinase, aldose reductase and sorbitol dehydrogenase activities were measured in glomeruli (G) and small arteries (SA) taken from normal and diabetic human kidneys, Hexokinase in diabetic G was 1688, which was significantly decreased from normal, 3147 mmoles/kg-1/h-1. Alodse reductase was significantly elevated in diabetic G,56-6, compared to normal G,10-8 mmoles/kg-1/h-1. In contrast, sorbitol dehydrogenase was significantly depressed in diabetic G, 3-7 VERSUs 10-9 mmoles/kg-1/h-1. The enzymatic changes observed in diabetic G would facilitate accumulation of sorbitol and therefore could contribute to the progression of glomerulosclerosis. The activity of hexokinase was also significantly reduced in SA, whereas aldose reductase and sorbitol dehydrogenase were unchanged.
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PMID:Quantitative histochemistry of the sorbitol pathway in glomeruli and small arteries of human diabetic kidney. 48 51

The isoenzyme pattern of hexokinase in rabbit red cells (erythrocytes, fetal erythrocytes and reticulocytes) were determined by means of agarose gel and disc electrophoresis. One duplicated hexokinase (4a and 4b according to the IUPAC-nomenclature) was detected in rabbit erythrocytes as also described for human erythrocytes. Besides the isoenzymes 4a and 4b reticulocytes also contain hexokinase 2 and 3 like rabbit and rat liver. The high KM glucose phosphorylating enzyme, hexokinase 1 could be demonstrated only under specific conditions in the reticulocytes during the initial stage of the anemia. After the fractionation of reticulocyte homogenates the total hexokinase activity was recovered in the mitochondria and cytosol to nearly equal amounts as revealed by the distribution of markers. Hexokinase 2 and 3 were detectable in reticulocytes and in isolated mitochondria only after the addition of certain dissociating agents. In contrast to the tightly bound mitochondrial hexokinases 2 and 3 the type 4a and 4b are more loosely bound and exhibit a bilocal distribution between mitochondria and cytosol of reticulocytes.
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PMID:Electrophoretic characterization and subcellular distribution of hexokinase isoenzymes in red blood cells of rabbits. 53 87

Hexokinase isozymic profiles from the liver of 68 vertebrate species are presented. The comparison of the diverse patterns observed, as well as the kinetic and physicochemical properties of the isozymes, reveals that the hexokinases from mammals are very similar to those from turtles and amphibians. The hexokinases from birds, lizards and snakes on the other hand are similar within themselves and different from the enzymes from mammals and amphibians. Liver pyruvate kinases show about the same behavior. The hexokinase system from vertebrate muscle however is very uniform in all the species studied consisting mainly of hexokinase B.
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PMID:Glucose utilization in vertebrates as a molecular probe for the study of evolution. 54 31

1. The changes with the time of the activities of some energy-supplying enzymes and of the hydrolytic enzyme, acid phosphatase, were studied over 2 weeks of complete ischaemia, produced in the rat soleus muscle by section of the abdominal aorta and terminal devascularization, leaving nerve and tendon intact. 2. Activities of glycolytic enzymes, oxidative enzymes, hexokinase and acid phosphatase are affected in a different manner. Activities of the glycolytic enzymes, lactate dehydrogenase, triosephosphate dehydrogenase and glycerolphosphate dehydrogenase, are lowest on the 1st day and increase thereafter. The first two reach the control values again on the 4th and 14th day, respectively, while glycerolphosphate dehydrogenase reaches about 50% of the control value on the 14th day. The maximum decrease in activity of the oxidative enzymes, citrate synthase, beta-hydroxyacyl-CoA-dehydrogenase and malate dehydrogenase occurs later (4th day); thereafter their activity returns slowly to control values, but does not reach them even on the 14th day. Hexokinase activity is slightly decreased on the 1st day; then it increased and reached on the 7th day twice the control value. Thus on the 1st day the activity of the enzymes of aerobic metabolism prevail, and on the 4th day those of anaerobic carbohydrate (glucose) metabolism; the recovery of enzyme activity of aerobic oxidation occurs later. 3. Acid phosphatase activity increased from the 2nd day onwards, reaching up to 3 times the control value on the 4th day and still twice that value on the 14th day. This agrees well with the histochemical picture of acid phosphatase. 4. Histochemical changes of alkaline phosphatase activity reveal destruction of capillary endothelial cells during the first few days after operation and their later proliferation from the periphery, correlating with the loss and recovery of oxidative enzyme activity.
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PMID:Effects of ischaemia on enzyme-activities in the soleus muscle of the rat. 57 Nov 16

Muscle hexokinase was ascertained in the gastrocnemius muscles of 160 male chicks. Observations were made in four age groups and two diets. No differences in enzyme activity were observed which could be attributed to the feeding of either the high-carbohydrate or high-fat diet. Hexokinase activity declined significantly between 6 and 12 days of age in the chicks fed the respective diets.
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PMID:The effect of non-protein energy source and age on hexokinase concentration in chick muscle. 60 32


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