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

Bacterial luciferase and NADH:FMN oxidoreductase have been immobilized onto arylamine glass beads. These immobilized enzymes can detect as little as 0.2 pmol of NADH per assay sample. Glucose-6-phosphate dehydrogenase has been co-immobilized with these enzymes, and with this system it is possible to quantitate 1 pmol of glucose 6-phosphate. By co-immobilizing a fourth enzyme, hexokinase, onto the glass beads, the system can reproducibly detect 20 pmol of glucose per liter. These immobilized enzyme systems are potentially superior to soluble enzymes by being reusable and much more stable. We compared the light-emitting properties of the immobilized enzyme systems with that of an equivalent mixture of the soluble enzymes. The most striking difference was the apparently more efficient conversion of NADH or glucose 6-phosphate to light by the immobilized enzymes. We used hydroxysteroid dehydrogenase in developing a soluble coupled system for the assay of androsterone and testosterone. The lower limit of detection was 100 pmol.
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PMID:Properties and uses of immobilized light-emitting enzyme systems from Beneckea harveyi. 3 21

The denaturation of eight purified yeast enzymes, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, 3-phosphoglycerate kinase, alcohol dehydrogenase, beta-fructosidase, hexokinase and glucose-6-phosphate isomerase, promoted under controlled conditions by the free fatty acids myristic and oleic, is selective. Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1 oxidoreductase, EC 1.1.1.49) is extremely sensitive to destabilization and was studied in greater detail. Results show that chain length and degree of unsaturation of fatty acids are important to their destabilizing effect, and that ligands of the enzyme can afford protection. The denaturation process results in more than one altered form. These results can be viewed in the perspective of the possibility that amphipathic substances, and in particular free fatty acids, may play a role for enzyme degradation in vivo, by initiating steps of selective denaturation.
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PMID:Selective denaturation of several yeast enzymes by free fatty acids. 35 87

We have investigated whether portal delivery of insulin as a result of intrahepatic islet cell autografts would prevent the development of metabolic alterations. Seven pancreatectomized dogs received islet autografts transplanted into the liver through the portal vein (PD). One year after transplantation, their intravenous glucose tolerance and insulin responses were similar to age-matched control (C) dogs (n = 5). Also, normal triglyceride content in arterial smooth muscle and striated muscle was observed in the dogs with portal insulin delivery in contrast to the substantial increases we observed in pancreatectomized dogs (n = 7) with pancreatic autografts that drained into the systemic circulation (SD). In these dogs, the tissue samples were taken at the age of 3 to 4 years. Triglyceride content (mean +/- SEM) in the aorta was 4.9 +/- 1.2 versus 2.6 +/- 0.6 versus 20.7 +/- 8.0 mumol/g (P less than .01) in C, PD, and SD models, respectively. The corresponding values for triglyceride content in striated muscles were 29.1 +/- 1.2, 25.9 +/- 1.5, and 171.4 +/- 46.6 mumol/g (P less than .01). Glucose-6-phosphate dehydrogenase (G-6-PDH) and malic enzyme, key enzymes for lipid synthesis, were also normal in the PD model, in contrast to the fivefold increased activity of these enzymes in the SD model (P less than .01). The glycolytic enzymes, hexokinase (HK) and phosphofructokinase (PFK), were normal compared with the decreased values in the SD. These data indicate that it is possible to normalize glucose and lipid metabolism in arterial walls by portal delivery of insulin, following intrahepatic islet cell transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Influence of portal delivery of insulin on intracellular glucose and lipid metabolism. 198 69

A histochemical analysis of reaction rates of a series of enzymes was performed in electromotor neurons of the weakly electric fish Apteronotus leptorhynchus. These neurons were selected because of their functional homogeneity. The high metabolic activity of these cells as well as their large size facilitate cytophotometric analysis in cryostat sections. Sections were incubated for the activity of hexokinase, glucose-6-phosphate dehydrogenase, succinate dehydrogenase, NADPH dehydrogenase, NADPH ferrihaemoprotein reductase and beta-hydroxybutyrate dehydrogenase. All media contained polyvinyl alcohol as tissue stabilizer and Nitro BT as final electron acceptor. Measurements were performed with a Vickers M85a cytophotometer. Linear relationships between the specific formation of formazan (test minus control reaction) and incubation time were obtained for all enzymes although some reactions showed an initial lag phase or an intercept with the ordinate. The relatively high activities of hexokinase, succinate dehydrogenase and the extremely low activity of hydroxybutyrate dehydrogenase indicate that energy is mainly supplied by glycolysis. Glucose-6-phosphate dehydrogenase showed a high activity whereas NADPH reductase and dehydrogenase activity were low in electromotor neurons, indicating that the NADPH generated is largely used for biosynthesis. Despite their synchronous firing pattern activity, electromotor neurons showed a considerable heterogeneity with respect to their metabolic activity.
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PMID:Enzyme reaction rate studies in electromotor neurons of the weakly electric fish Apteronotus leptorhynchus. 251 71

In order to further investigate insulin insensitivity in pregnancy, the activities of key enzymes in glycolysis and lipid metabolism were measured in adipose and muscle tissue biopsies from 20 normal pregnant women undergoing caesarean section at term, and 23 non-pregnant women of similar age and body weight undergoing gynaecological surgery. The activity of pyruvate kinase was decreased in pregnant women in both adipose tissue (0.015 (0.009-0.024) (median and range) vs 0.020 (0.009-0.038) Ug-1 wet weight, p less than 0.05) and muscle tissue (6.7 (3.6-10.9) vs 12.0 (2.8-16.2) U g-1 wet weight, p less than 0.001). The activity of hexokinase was decreased in adipose tissue only (0.045 (0.022-0.085) vs 0.057 (0.025-0.097) U g-1 wet weight, p less than 0.05), while the activity of phosphofructokinase was decreased in muscle tissue only (1.3 (0.7-2.6) vs 2.1 (0.3-4.5) U g-1 wet weight, p less than 0.01). Glucose-6-phosphate dehydrogenase activity was increased in muscle tissue (0.30 (0.11-0.59) vs 0.17 (0.09-0.48) U g-1 wet weight, p less than 0.05), while the activity of hydroxyacyl-CoA dehydrogenase was decreased in adipose tissue (0.5 (0.3-1.1) vs 1.0 (0.5-2.3) U g-1 wet weight p less than 0.001) from the pregnant women. Similar results were found when enzyme activities were calculated per gram of protein, but with poorer reproducibility.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Activity of enzymes of glucose and triglyceride metabolism in adipose and muscle tissue from normal pregnant women at term. 252 54

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

1. The maximum activities of some key enzymes, which provide a quantitative indices of flux through several important pathways have been measured in brain, liver, muscle, white and brown adipose tissue and lymphocytes of mature and aged rats. 2. The results were expressed as mumol/min per g fresh weight and nmol/min per mg protein. 3. On the both basis, as compared to mature rats, hexokinase activity is decreased in brown adipose tissue and increased in soleus muscle. 4. Glucose-6-phosphate dehydrogenase activity is decreased in most tissues and increased in brain. 5. Citrate synthase activity, which provides a qualitative index of the Krebs cycle, is decreased in white adipose tissues and lymphocytes. 6. Glutaminase activity is decreased in brain, white and brown adipose tissues but is increased in lymphocytes.
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PMID:Maximal activities of key enzymes of glutaminolysis, glycolysis, Krebs cycle and pentose-phosphate pathway of several tissues in mature and aged rats. 258 60

The rate at which the activities of red cell enzymes decay during maturation of the reticulocyte and ageing of the erythrocyte is poorly understood. It has recently been suggested that loss of enzyme activity may be rapid during reticulocyte maturation and occur slowly thereafter. We have now devised a rabbit model in which reticulocytosis is combined with transfusional polycythaemia. This makes it possible to follow the enzymatic activity of a cohort of reticulocytes without the interfering effect of newly formed cells. In this model the reticulocyte count of the experimental animals falls from about 60% to subnormal levels within 4 d. Red cell hexokinase activity declined rapidly with more than half of the activity being lost within 7 d, little change occurring thereafter. Glucose-6-phosphate dehydrogenase activity declined more gradually, but also followed a biphasic course. The fall of pyrimidine 5' nucleotidase activity was the slowest of the three age-dependent enzymes studied. This is consistent with our observations in children with transient erythroblastopenia of childhood, in which this enzyme, alone of the age-dependent enzymes, was found to be decreased in a senescent red cell population. In contrast to the three age-dependent enzymes studied, the activity of lactate dehydrogenase remained unchanged during the course of the experiment. These studies provide direct verification of the suggestion that the decline of red cell enzyme activities may be biphasic. They show, moreover, that enzyme decay is not only rapid in reticulocytes, but also in young erythrocytes.
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PMID:The in vivo ageing of red cell enzymes: direct evidence of biphasic decay from polycythaemic rabbits with reticulocytosis. 283 67

Abnormal glucose and lipid metabolism in striated muscles and arterial wall has been demonstrated in 3 species: the pig, the dog, and human Type 2 diabetic patients, sharing the common feature of peripheral hyperinsulinaemia. In this study eighteen consecutive patients undergoing coronary bypass surgery and eight control patients were examined. Prior to surgery an oral glucose tolerance test showed that eleven out of eighteen patients had impaired glucose tolerance and significantly elevated fasting immune reactive insulin (IRI) and C-peptide concentrations. There was a statistically significant correlation between the 2 hour blood glucose value and the fasting plasma insulin level (R = 0.55, p less than 0.05). During the operation, aortic and muscle biopsies were taken. The eighteen patients undergoing coronary bypass surgery showed disturbances in glucose metabolism, i.e. decreased activity of glycolytic enzymes (hexokinase 0.30 +/- 0.06 versus 0.40 +/- 0.06 U/g, p less than 0.001, and phosphofructokinase 0.48 +/- 0.09 versus 0.61 +/- 0.07 U/g, p less than 0.01). Malic enzyme activity was increased in all patients (0.17 +/- 0.03 versus 0.06 +/- 0.02 U/g, p less than 0.001). Glucose-6-phosphate dehydrogenase was increased in the eleven patients with impaired glucose tolerance (0.55 +/- 0.10 versus 0.30 +/- 0.07, p less than 0.01) parallel to a significant increase in triglyceride content in the aortic wall (16.1 +/- 4.8 versus 3.7 +/- 3.2 mumol/g, p less than 0.01) as well as in the striated muscles (374 +/- 44 versus 48 +/- 6 mumol/g, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intracellular metabolism in biopsies from the aorta in patients undergoing coronary bypass surgery. 295 78


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