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)

Training and detraining had little effect on the activity of glycogen synthase, hexokinase, glycerol 3-phosphate dehydrogenase or total protein. The activity of 3-hydroxyacyl-CoA dehydrogenase increased markedly during training. After 5 weeks of detraining, the activity of 3-hydroxyacyl-CoA dehydrogenase was returning to pre-training values, whilst by 10-week detraining, the levels were increasing again.
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PMID:The effect of training and detraining on several enzymes in horse skeletal muscle. 9 93

1. Developmental enzyme alterations were investigated in skeletal muscle of the hereditary progressive muscular dystrophy (PMD) mice of C57BL/6J strain. 2. Enzymes examined were classified into three groups according to changes of activities in dystrophy muscle during ageing. Activities of creatine kinase (EC 2.7.3.2), pyruvate kinase (EC 2.7.1.40), glycogen phosphorylase (EC 2.4.1.1), and fructose-biphosphate aldolase (EC 4.1.2.13), each of which had the respective muscle specific isoenzyme of extremely high activity in normal adult skeletal muscle, decreased rapidly in dystrophy muscle from the early stage of the disease with ageing. Activities of glycogen synthase (EC 2.4.1.11) and hexokinase (EC 2.7.1.1) were higher in dystrophy muscle in the early stage but decreased gradually to lower levels than those in the control with ageing. Activities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) were always much higher in dystrophy muscle than in the control, with no relation to ageing. 3. Isoenzymes of creatine kinase, pyruvate kinase and phosphorylase in dystrophy muscle were mainly the muscle types, indicating that muscle differentiation was not blocked profoundly even in dystrophy muscle. In limited cases, especially in the early stage of the disease, very weak activities of the non-muscle fetal type isoenzymes of creatine kinase and phosphorylase were detected, apparently associated with partial muscle regeneration in dystrophy muscle.
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PMID:Enzyme alteration in skeletal muscle of mice with muscular dystrophy. 41 23

There are important differences between the short- and long-term effects of adrenaline on determinants of glucose tolerance. To assess this metabolic adaptation at tissue level, the present study examined the effect of acute and prolonged in vivo elevation of adrenaline on glycogen metabolism and glycolysis in skeletal muscle. Adrenaline (50 ng.kg-1.min-1) was infused for 2 h or 74 h and the results compared with 1 h 0.9% NaCl infusion in six trained dogs. Muscle glycogen content was reduced by long-term adrenaline (161 +/- 17 vs NaCl 250 +/- 24 mumol/g dry weight; p less than 0.05) but not short-term adrenaline (233 +/- 21) indicating a sustained effect of adrenaline on glycogen metabolism. Acutely, glycogen synthase I was reduced (short-term adrenaline 12 +/- 6 vs NaCl 22 +/- 7 mumol glycosyl units.g-1.min-1; p less than 0.05) but returned to normal with prolonged adrenaline infusion (20 +/- 5). In contrast, Km for glycogen phosphorylase alpha was not changed acutely (short-term adrenaline 31 +/- 6 vs NaCl 27 +/- 7 mmol/l inorganic phosphate) but was reduced during long-term infusion (19 +/- 4; p less than 0.05 vs short-term adrenaline). Thus, with short- and long-term adrenaline infusion, there were different enzyme changes, although likely to promote glycogenolysis in both cases. In the glycolytic pathway the substrates glucose 6-phosphate and fructose 6-phosphate did not change significantly and hexokinase was not inhibited. Acutely, phosphofructokinase had reduced Vmax (short-term adrenaline 34 +/- 6 vs NaCl 44 +/- 5 U/g; p less than 0.05) but was still above the maximal operating rate in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contrasting action of short- and long-term adrenaline infusion on dog skeletal muscle glucose metabolism. 138 57

Renal clear cell tubules and clear/acidophilic cell tumors were induced in male Sprague-Dawley rats by 7 weeks oral administration (stop model) of N-nitrosomorpholine (NNM) at a concentration of 12 mg/100 ml in the drinking water. Twelve, 23 and 34 weeks after withdrawal of NNM serial cryostat sections of the kidneys were histochemically analyzed for the following parameters: glucose transporter proteins (GLUT1, GLUT2), glycogen content and the activities of glycogen synthase (SYN), glycogen phosphorylase (PHO), glucose-6-phosphatase (G6Pase), glucose-6-phosphate dehydrogenase (G6PDH), hexokinase (HK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), alkaline phosphatase (ALP), acid phosphatase (ACP) and gamma-glutamyltransferase (GGT). Clear cell (glycogenotic) tubules first appeared at 23 weeks, and clear/acidophilic cell tumors at 34 weeks after withdrawal of the carcinogen. G6Pase, ALP, GGT and GLUT2 were absent in clear cell tubules, clear/acidophilic cell tubules, and clear/acidophilic cell tumors indicating a sequential origin of all these types of lesions from the collecting duct system, in line with previous morphological findings. In comparison to the collecting duct epithelium, glycogenotic tubules demonstrated an increased activity of PHO and reduced activities of glycolytic and mitochondrial enzymes, which were accompanied by a strongly reduced expression of GLUT1. Moderately increased activities of glycolytic and mitochondrial enzymes were observed in the clear cells of clear/acidophilic cell tubules and tumors compared with those in glycogenotic tubules. They had slightly increased activities of the glycolytic enzymes GAPDH and PK compared with normal collecting duct epithelium, while most of them were nearly lacking in GLUT1. Our findings suggest that glycogen storage is not due to an increased uptake of glucose from the blood, but results from a disturbance in intracellular flux of metabolites. The development of clear cell tubules from the normal collecting duct epithelium is accompanied by a markedly decreased expression of GLUT1 along with a reduction in glycolytic and mitochondrial enzymes. This reduction of enzyme activities is replaced by an increase in enzyme activities in clear/acidophilic cell tumors indicating a fundamental shift in carbohydrate metabolism during progression from preneoplastic to neoplastic lesions.
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PMID:Sequential changes in glycogen content, expression of glucose transporters and enzymic patterns during development of clear/acidophilic cell tumors in rat kidney. 147 41

The effect of hyperglycemia on whole body substrate utilization and the metabolic profile of skeletal muscle has been investigated. Eight glucose-tolerant men were infused with somatostatin (S) for 190 min. During the last 120 min of S infusion, glucose was infused to achieve a steady-state plasma level of 26 mmol/l. Biopsies were obtained from the quadriceps femoris muscle immediately before and 35 and 120 min after induction of hyperglycemia. Steady-state glucose disposal during hyperglycemia averaged (+/- SE) 33.8 +/- 3.2 mumol.kg fat-free mass-1.min-1, and approximately 70% of the glucose disposal was accounted for by skeletal muscle. Intracellular glucose increased from 0.9 +/- 0.2 mmol/kg dry wt during S to 9.5 +/- 2.5 during hyperglycemia (P less than 0.01). It was estimated that approximately 35% of the glucose taken up by muscle during 120 min of hyperglycemia was not phosphorylated. Muscle contents of alpha-D-glucose 1,6-diphosphate, D-glucose 6-phosphate, ATP, ADP, and AMP (both of which are based on the phosphocreatine-to-creatine ratio), which have been shown to inhibit hexokinase in vitro, did not change significantly during hyperglycemia, nor were there any significant changes in any of the other postphosphofructokinase intermediates, D-fructose 2,6-diphosphate, and citrate. Hyperglycemia did not alter the fractional activities of glycogen synthase or phosphorylase, nor total phosphorylase activity. However, hyperglycemia resulted in a 55% increase in glycogen synthase-specific activity (P less than 0.01). It is concluded that hyperglycemia results in a marked increase in muscle glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hyperglycemia induces accumulation of glucose in human skeletal muscle. 167 95

The effect of epinephrine (E) infusion on insulin-mediated glucose metabolism in humans has been studied. Eight glucose-tolerant men were studied on two separate occasions: 1) during 120 min of euglycemic hyperinsulinemia (UH, approximately 5 mM; 40 mU.m-2.min-1); and 2) during UH while E was infused (UHE, 0.05 microgram.kg-1.min-1). Biopsies were taken from the quadriceps femoris muscle before and after each clamp. Glucose disposal, correcting for endogenous glucose production, was 36 +/- 3 and 18 +/- 2 (SE) mumol.kg fat-free mass (FFM)-1.min-1 during the last 40 min of UH and UHE, respectively (P less than 0.001). Nonoxidative glucose disposal (presumably glycogenesis) averaged 23.0 +/- 3.0 and 4.0 +/- 1.1 (P less than 0.001), whereas carbohydrate oxidation (which is proportional to glycolysis) averaged 13.1 +/- 1.4 and 15.3 +/- 1.1 mumol.kg FFM-1.min-1 (P less than 0.05) during UH and UHE, respectively. UHE resulted in significantly higher contents of UDP-glucose, hexose monophosphates, postphosphofructokinase intermediates, and glucose 1,6-bisphosphate (G-1,6-P2) in muscle (P less than 0.05-0.001), but there were no significant differences in high-energy phosphates or fructose 2,6-bisphosphate (F-2,6-P2) between treatments. Fractional activities of phosphorylase increased (P less than 0.01), and glycogen synthase decreased (P less than 0.001) during UHE. It is concluded that E inhibits insulin-mediated glycogenesis because of an inactivation of glycogen synthase and an activation of glycogenolysis. E also appears to inhibit insulin-mediated glucose utilization, at least partly, because of an increase in G-6-phosphate (which inhibits hexokinase) and enhances glycolysis by G-1,6-P2-, fructose 6-phosphate-, and F-1,6-P2-mediated activation of PFK.
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PMID:Epinephrine inhibits insulin-mediated glycogenesis but enhances glycolysis in human skeletal muscle. 190 Jun 69

Effect of feeding isolated dietary fiber from M. paradisiaca on the metabolism of carbohydrates in the liver has been studied. Fiber fed rats showed significantly lower levels of fasting blood glucose and higher concentration of liver glycogen. Activity of glycogen phosphorylase, glucose-1-phosphate, uridyl transferase and glycogen synthase was significantly higher while phosphoglucomutase activity showed lower activity. Activity of some glycolytic enzymes, viz. hexokinase and pyruvic kinase was lower. Glucose-6-phosphatase showed higher activity while fructose 1-6 diphosphatase activity was not affected. Glucose-6-phosphate dehydrogenase on the other hand showed higher activity. The changes in these enzyme activities have been attributed due to the effect of higher concentration of bile acids produced in the liver as a result of feeding fiber. Evidence for this has been obtained by studying the in vitro effect of cholic acid and chenodeoxy cholic acid.
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PMID:Effect of dietary fiber from banana (Musa paradisiaca) on metabolism of carbohydrates in rats fed cholesterol free diet. 255 80

Twenty-one enzymes of different metabolic systems were measured in the rabbit fast-twitch tibialis anterior (TA) muscle after electrical stimulation (10 Hz, 24 h/day) for 1 day to 10 wk. Nine analytical methods are either new, (3-oxoacid CoA-transferase, branched-chain-amino-acid aminotransferase, carnitine acetyltransferase, thiolase), improved (glutamate dehydrogenase, glycogen synthase, adenylic acid deaminase), or specially adapted (hexokinase, phosphoglucomutase). The activities (based on protein) of 12 mitochondrial or partly mitochondrial enzymes were lower in control TA than in control (slow) soleus (30-84% of soleus level). After 2 wk, 11 of these had surpassed the control soleus level. Maximal increases (3- to 14-fold) occurred after 2-5 wk, and thereafter six of the enzymes declined, whereas the other five maintained or increased their levels. Five glycolytic and two high-energy phosphate transfer enzymes, originally much higher in control TA than in control soleus, decreased gradually to levels at 8-10 wk only 27-123% higher than in soleus. Noncollagen protein concentration dropped 46%, explained largely by a sixfold increase in extracellular (chloride) space and a modest increase in collagen. The data constitute strong evidence for coordinate regulation of (mainly cytosolic) enzymes of glycolysis, glycogenolysis, gluconeogenesis, and high-energy phosphate transfer. Changes in the (mainly mitochondrial) enzymes of oxidative metabolism were more divergent, partly because of a hitherto undescribed secondary phase in the metabolic response. This phase may reflect a lower energy consumption in muscles adapted to continuous activity.
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PMID:Chronic stimulation of mammalian muscle: changes in enzymes of six metabolic pathways. 294 40

Polymyxin B (PMB), a cyclic decapeptide antibiotic, inhibits the hypoglycemic effect of insulin in vivo. To elucidate the mechanism of PMB action, we have studied its effect in vitro on insulin-stimulated pathways in the mouse skeletal muscle. PMB, added to the incubation mixture, specifically inhibited insulin-stimulated 2-deoxyglucose transport and alpha-aminoisobutyric acid uptake in the isolated soleus muscle but did not affect the basal rates of transport (measured in the absence of insulin). PMB did not alter insulin binding and hexokinase activity. PMB effect was observed at all deoxyglucose concentrations tested, and PMB was also able to inhibit vanadate-stimulated glucose transport. By contrast, insulin activation of glycogen synthase was not prevented by PMB. Basal and maximally insulin-stimulated insulin receptor tyrosine kinase activity, tested in a cell-free system, was similar for both autophosphorylation and phosphorylation of exogenous substrates in the absence or in the presence of PMB. Furthermore, the insulin sensitivity of the kinase was increased in the presence of PMB. Our results suggest that the anti-insulin effect of PMB observed in vivo is due to an inhibition of insulin-stimulated glucose transport in the skeletal muscle perhaps through a specific blockade of the insulin-induced translocation of the glucose carriers.
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PMID:Polymyxin B selectively inhibits insulin effects on transport in isolated muscle. 303 Jan 25

The state of activation of glycogen synthase enhanced by glucose, other sugars and gluconeogenic precursors shows a strong positive correlation with the intracellular concentrations of glucose 6-P when ATP concentrations remain constant. The concentrations of glucose 6-P achieved upon incubation of hepatocytes with glucose plus mannoheptulose, an inhibitor of glucokinase and hexokinase, were lower than those found when the incubation was carried out with glucose alone. Under these conditions, in keeping with the decrease in glucose 6-P, the activation of glycogen synthase by glucose was also impaired. On the other hand the inactivation of glycogen phosphorylase was not altered in the presence of mannoheptulose.
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PMID:Glucose 6-phosphate plays a central role in the activation of glycogen synthase by glucose in hepatocytes. 310 79


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