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)

The present study was aimed to evaluate the hypoglycemic efficacy in an aqueous extract of seeds of two varieties, namely a country and a hybrid variety of Momordica charantia (MCSEt1 and MCSEt2) respectively in streptozotocin (STZ) induced diabetic rats. STZ-induced diabetic rats were treated with aqueous extracts of MCSEt1 and t2 for a period of 30 days. MCSEt1 and t2 extract treatment to diabetic rats resulted in a significant reduction in blood glucose, glycosylated hemoglobin, lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase and glycogen phosphorylase, and a concomitant increase in the levels of hemoglobin, glycogen and activities of hexokinase and glycogen synthase. These results clearly show the antidiabetic properties of Momordica charantia. Both the varieties showed safe and significant hypoglycemic effects which were more pronounced in MCSEt1 compared to MCSEt2 and glibenclamide.
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PMID:Antidiabetic activity of Momordica charantia seeds on streptozotocin induced diabetic rats. 1591 91

In the present study, we investigated the mechanisms by which resistin (100 nM, 1 h) affects glycogen synthesis in L6 skeletal muscle cells. The activity of glycogen synthase, the major enzyme in glycogen synthesis, is determined by both its covalent phosphorylation and allostery through intracellular glucose-6-phosphate. Covalent phosphorylation of glycogen synthase was not altered by resistin and, accordingly, phosphorylation of GSK-3alpha/beta and Akt remained unchanged. The rate of glucose-6-phosphate formation, however, was decreased by resistin both in the absence and presence of insulin; in the absence of insulin, resistin decreased glucose-6-phosphate formation by reducing hexokinase type I activity without affecting glucose uptake; by contrast, in the presence of insulin, resistin decreased glucose-6-phosphate formation by reducing the Vmax of glucose uptake without changing hexokinase type I activity. In conclusion, short-term resistin incubation impairs glycogen synthesis by reducing the rate of glucose-6-phosphate formation involving, however, differential mechanisms in basal and insulin-stimulated states.
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PMID:Resistin impairs basal and insulin-induced glycogen synthesis by different mechanisms. 1704 21

1. Diabetes mellitus is a serious metabolic disorder with micro- and macrovascular complications that results in significant morbidity and mortality. 2. The aim of the present study was to evaluate the hypoglycaemic efficacy of commonly used traditional Indian plants, such as Murraya koenigii, Mentha piperitae, Ocimum sanctum and Aegle marmelos, in streptozotocin (STZ)-induced experimental rats. 3. Oral administration of the ethanolic extract of these plants resulted in a significant decrease in the levels of blood glucose, glycosylated haemoglobin and urea, with a concomitant increase in glycogen, haemoglobin and protein, in diabetic rats. Treatment with these plant extracts also resulted in an increase in insulin and C-peptide levels and glucose tolerance. 4. The decreased activities of carbohydrate-metabolising enzymes, such as hexokinase, glucose-6-phosphate dehydrogenase and glycogen synthase, in diabetic rats were significantly elevated towards near normal in rats treated with extracts of M. koenigii, O. sanctum and A. marmelos; the increased activities of lactate dehydrogenase, fructose-1,6-bisphosphatase, glucose-6-phosphatase and glycogen phosphorylase in STZ diabetic rats were significantly reduced following treatment with the plant extracts. 5. Elevated specific binding of [(125)I]-labelled insulin to the receptor found in diabetic rats was markedly decreased in extract-treated groups. However, treatment of diabetic rats with M. piperitae did not result in any significant modification in all parameters. 6. Phytochemical screening conducted by us revealed the presence of biologically active ingredients in the ethanolic extracts of M. koenigii, O. sanctum and A. marmelos, which may readily account for the observed hypoglycaemic activity.
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PMID:Biochemical evaluation of antidiabetogenic properties of some commonly used Indian plants on streptozotocin-induced diabetes in experimental rats. 1718 94

Different values exist for glucose metabolism in white matter; it appears higher when measured as accumulation of 2-deoxyglucose than when measured as formation of glutamate from isotopically labeled glucose, possibly because the two methods reflect glycolytic and tricarboxylic acid (TCA) cycle activities, respectively. We compared glycolytic and TCA cycle activity in rat white structures (corpus callosum, fimbria, and optic nerve) to activities in parietal cortex, which has a tight glycolytic-oxidative coupling. White structures had an uptake of [(3)H]2-deoxyglucose in vivo and activities of hexokinase, glucose-6-phosphate isomerase, and lactate dehydrogenase that were 40-50% of values in parietal cortex. In contrast, formation of aspartate from [U-(14)C]glucose in awake rats (which reflects the passage of (14)C through the whole TCA cycle) and activities of pyruvate dehydrogenase, citrate synthase, alpha-ketoglutarate dehydrogenase, and fumarase in white structures were 10-23% of cortical values, optic nerve showing the lowest values. The data suggest a higher glycolytic than oxidative metabolism in white matter, possibly leading to surplus formation of pyruvate or lactate. Phosphoglucomutase activity, which interconverts glucose-6-phosphate and glucose-1-phosphate, was similar in white structures and parietal cortex ( approximately 3 nmol/mg tissue/min), in spite of the lower glucose uptake in the former, suggesting that a larger fraction of glucose is converted into glucose-1-phosphate in white than in gray matter. However, the white matter glycogen synthase level was only 20-40% of that in cortex, suggesting that not all glucose-1-phosphate is destined for glycogen formation.
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PMID:Evidence for a higher glycolytic than oxidative metabolic activity in white matter of rat brain. 1731 1

Culturing hepatocytes with a combination of LPS, TNF-alpha, IL-1beta and IFN-gamma resulted in an inhibition of glucose output from glycogen and prevented the repletion of glycogen in freshly cultured cells. The reduced glycogen mobilisation correlated with the lower cell glycogen content and reduced rate of glycogen synthesis from [U-(14)C]glucose rather than alterations in either total phosphorylase or phosphorylase a activity. There was no change in the percentage of glycogen exported as glucose nor the production of lactate plus pyruvate indicating that redistribution of the Gluc-6-P cannot explain the failure of the liver to export glucose. Although changes in glycogen mobilisation correlated with NO production, inhibition of NO synthase by inclusion of L-NMMA in the culture medium failed to prevent the inhibition of either glycogen accumulation or mobilisation by the proinflammatory cytokines, precluding the involvement of NO in this response. LPS plus cytokine treatment had no effect on total glycogen synthase activity although the activity ratio was lowered, indicative of increased phosphorylation. The inhibition of glycogen synthesis correlated with a fall in the intracellular concentrations of Gluc-6-P and UDP-glucose and in the absence of measured changes in kinase activity, it is suggested that the fall in Gluc-6-P reduces both substrate supply and glycogen synthase phosphatase activity. The fall in Gluc-6-P coincided with a reduction in total glucokinase and hexokinase activity within the cells, but no significant change in either the translocation of glucokinase or glucose-6-phosphatase activity. This demonstrates direct cytokine effects on glycogen metabolism independent of changes in glucoregulatory hormones.
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PMID:The control of hepatic glycogen metabolism in an in vitro model of sepsis. 1793 98

Resveratrol, a ubiquitous stress-induced phytoalexin, has demonstrated a wide variety of biological activities which make it a good candidate for the treatment of diabetes mellitus. The present study was aimed to evaluate its therapeutic potential by assaying the activities of key enzymes of carbohydrate metabolism in streptozotocin-nicotinamide-induced diabetic rats. The daily oral treatment of resveratrol (5 mg/kg body weight) to diabetic rats for 30 days demonstrated a significant (p<0.05) decline in blood glucose and glycosylated hemoglobin levels and a significant (p<0.05) increase in plasma insulin level. The altered activities of the key enzymes of carbohydrate metabolism such as hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen phosphorylase in liver and kidney tissues of diabetic rats were significantly (p<0.05) reverted to near normal levels by the administration of resveratrol. Further, resveratrol administration to diabetic rats improved hepatic glycogen content suggesting the antihyperglycemic potential of resveratrol in diabetic rats. The obtained results were compared with glyclazide, a standard oral hypoglycemic drug. Thus, the modulatory effects of resveratrol on attenuating these enzymes activities afford a promise for widespread use for treatment of diabetes in the future.
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PMID:Modulatory effects of resveratrol on attenuating the key enzymes activities of carbohydrate metabolism in streptozotocin-nicotinamide-induced diabetic rats. 1905 88

The dominant RN mutation in pigs results in excessive glycogen storage in skeletal muscle. The mutation is situated in the PRKAG3 gene, which encodes a muscle-specific isoform of the AMP-activated protein kinase (AMPK) gamma3 subunit. AMPK is an important regulator of carbohydrate and fat metabolism in mammalian cells. The aim of the present study was to examine the effect of exercise on glycogen synthesis signalling pathways in muscle and to study enzyme activities of importance in carbohydrate metabolism in pigs with or without the PRKAG3 mutation. Glycogen content, metabolic enzyme activities and expression or phosphorylation of signalling proteins were analysed in skeletal muscle specimens obtained at rest, after a single treadmill exercise bout and after 3 h recovery. The PRKAG3 mutation carriers had higher glycogen content, a tendency for lower expression of AMPK (P < 0.07) and higher hexokinase and phosphorylase activities, whereas citrate synthase, 3-hydroxyacyl-CoA dehydrogenase and glycogen synthase activities did not differ between genotypes. Carriers and non-carriers of the RN mutation showed a similar degradation of glycogen after exercise, whereas the rate of resynthesis was faster in the carriers. Acute exercise stimulated Akt phosphorylation on Ser(473) in both genotypes, and the effect was greater in the carriers than in the non-carriers. Acute exercise also stimulated phosphorylation of Akt substrate of 160 kDA and Glycogen synthase kinase 3 in the carriers and GSK3alpha in the non-carriers. In conclusion, the increased rate of glycogen synthesis following exercise in pigs carrying the PRKAG3 mutation correlates with an increased signalling response of Akt and its substrate, AS160, and a higher activity of hexokinase, indicating an increased glucose influx and phosphorylation of glucose, directed towards glycogen synthesis.
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PMID:Effects of exercise on muscle glycogen synthesis signalling and enzyme activities in pigs carrying the PRKAG3 mutation. 2002 49

During diabetes mellitus, endogenous hepatic glucose production is increased as a result of impaired activities of the key enzymes of carbohydrate metabolism, which leads to the condition known as hyperglycemia. D-pinitol, a bioactive constituent isolated from soybeans, has been shown to reduce hyperglycemia in experimental diabetes. We therefore designed this study to investigate the effect of oral administration of D-pinitol (50 mg/kg b. w. for 30 days) on the activities of key enzymes in carbohydrate and glycogen metabolism in the liver tissues of streptozotocin-induced diabetic rats. The efficacy was compared with glyclazide, a standard hypoglycemic drug. Oral administration of D-pinitol to diabetic group of rats showed a marked decrease in the levels of blood glucose, glycosylated hemoglobin and an increase in plasma insulin and body weight. The activities of the hepatic enzymes such as hexokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase, glycogen synthase and hepatic glycogen content were significantly (p < 0.05) increased whereas the activities of glucose-6-phosphatase, fructose-1,6-bisphosphatase, lactate dehydrogenase and glycogen phosphorylase were significantly (p < 0.05) decreased in diabetic rats treated with D-pinitol. The results suggest that alterations in the activities of key metabolic enzymes of carbohydrate metabolism could be one of the biochemical rationale by which D-pinitol attenuates the hyperglycemic effect in diabetic rats.
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PMID:D-pinitol attenuates the impaired activities of hepatic key enzymes in carbohydrate metabolism of streptozotocin-induced diabetic rats. 2003 88

Identifying the mechanisms by which insulin regulates glucose metabolism in skeletal muscle is critical to understanding the etiology of insulin resistance and type 2 diabetes. Our knowledge of these mechanisms is limited by the difficulty of obtaining in vivo intracellular data. To quantitatively distinguish significant transport and metabolic mechanisms from limited experimental data, we developed a physiologically based, multiscale mathematical model of cellular metabolic dynamics in skeletal muscle. The model describes mass transport and metabolic processes including distinctive processes of the cytosol and mitochondria. The model simulated skeletal muscle metabolic responses to insulin corresponding to human hyperinsulinemic-euglycemic clamp studies. Insulin-mediated rate of glucose disposal was the primary model input. For model validation, simulations were compared with experimental data: intracellular metabolite concentrations and patterns of glucose disposal. Model variations were simulated to investigate three alternative mechanisms to explain insulin enhancements: Model 1 (M.1), simple mass action; M.2, insulin-mediated activation of key metabolic enzymes (i.e., hexokinase, glycogen synthase, pyruvate dehydrogenase); or M.3, parallel activation by a phenomenological insulin-mediated intracellular signal that modifies reaction rate coefficients. These simulations indicated that models M.1 and M.2 were not sufficient to explain the experimentally measured metabolic responses. However, by application of mechanism M.3, the model predicts metabolite concentration changes and glucose partitioning patterns consistent with experimental data. The reaction rate fluxes quantified by this detailed model of insulin/glucose metabolism provide information that can be used to evaluate the development of type 2 diabetes.
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PMID:Computational model of cellular metabolic dynamics: effect of insulin on glucose disposal in human skeletal muscle. 2033 60

Muscle glycogen synthase (GYS1) is the rate-limiting enzyme in glycogen synthesis, and its activity is regulated by the phosphorylation states of certain amino acid residues encoded by the GYS1 gene. In the present study, the authors molecularly characterized the full-length equine GYS1 (eGYS1) cDNA and found that it contains a less common polyadenylation signal (AATACA). An amino acid alignment with other mammalian GYS1 showed that the phosphorylation sites in eGYS1 are completely conserved. Genomic DNA analysis revealed that the equine-specific substitutions (Glu 16 Asp and Ala 252 Thr) were completely conserved among six equine species. The tissue expression profiles of eGYS1, equine type II hexokinase (eHKII) and muscle-type phosphofructokinase (ePFKM) were determined by real-time PCR and western blot analysis. The mRNA expression level of eGYS1 was significantly higher in the cervical muscle as compared to other tissues. The cervical muscle and heart tissue samples contained a broad range of eGYS1 protein bands that appeared to reflect multiple phosphorylation states. eHKII was predominately expressed only in the cervical muscle; unlike its expression in other mammals, eHKII was not substantially expressed in the insulin-responsive heart or adipose tissue of horse. The expression level of ePFKM mRNA was significantly higher in the heart than in the cervical muscle, which differs from the PFKM expression pattern of other mammals. These tissue expression profiles are fundamental for the understanding of equine glucose metabolism.
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PMID:Molecular characterization of glycogen synthase 1 and its tissue expression profile with type II hexokinase and muscle-type phosphofructokinase in horses. 2038 48


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