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)

A cross-sectional study was carried out to examine the activities of certain enzymes representing aerobic and anaerobic energy metabolism as well as the biosynthesis of collagen of M. vastus lateralis in 23 male endurance athletes in habitual training, aged 33 to 70 years. 23 sedentary healthy men of corresponding ages were selected for the control group. The mean maximal oxygen uptake of the trained subjects was 53.6 ml-kg--1. min--1 and that of the control subjects 36.3 ml-kg--1. min--1. As compared to the control group the trained subjects had significantly higher values in the muscle malate dehydrogenase, succinate dehydrogenase and prolyl hydroxylase activities, whereas the opposite was true in the activity of lactate dehydrogenase. In hexokinase and creatine phosphokinase no marked differences between the groups were observed. The results showed that endurance training leads to increased activities of oxidative enzymes in the skeletal muscle. The adaptation changes were also observed in old men. The increased activity of prolyl hydroxylase may reflect the general enzymatic adaptation to physical training. A possibility exists that the turnover of muscle collagen in endurance athelets is continuously faster than that in sedentary men of corresponding ages.
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PMID:Enzyme activities in muscle and connective tissue of M. Vastus lateralis in habitually training and sedentary 33 to 70-year-old men. 17 30

Two new methods of activation were developed to graft enzymes on collegen films. They involved chemical modifications of surface groups of collagen either by Woodward's reagent "K" or by EDC, a water-soluble derivative of carbodiimide. EDC was a better coupling agent and a detailed study was conducted with this agent. It could be used either in a global method of activation and coupling, or in a two-step procedure of activation of collagen, followed by spontaneous coupling of enzyme. All enzymes tested were successfully bound: malate dehydrogenase, lactate dehydrogenase, aspartate aminotransferase, urease, creatine kinase, hexokinase. The influence on the yield of grafted enzyme, of pretreatment of films, time and temperature of EDC activation, concentration of EDC and enzyme, protecting agents was studied. Stability of enzyme activity on storage was greatly increased after grafting. A co-grafted dual system creatine kinase/heoxkinase, was achieved which exhibited a good efficiency. A striking renaturing process at 0-4degreesC after thermal denaturation, was observed with hexokinase.
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PMID:Grafting of enzymes on collagen films using Woodward's reagent "K" and a water-soluble carbodiimide derivative. 95 53

The contents of collagen, hexosamine, phospholipids, and cholesterol and the activities of acid and alkaline phosphatases, glutamic oxalo-acetate transaminase, glutamic pyruvate transminase, aldolase, hexokinase, and lactic dehydrogenase were determined in the lungs of rats 150 days after the intratracheal injection of amosite, anthophyllite, and chyrsotile. Anthophyllite did not cause any significant change, while amosite and chrysotile caused significant increases in the contents of collagen and mucopolysaccharides. Lactic dehydrogenase and acid phosphatase activities were increased by all the dusts, while the othe enzymes were not seriously affected. The biochemical significance of the findings in relation to abestosis was discussed.
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PMID:Biochemical changes caused by asbestos dust in the lungs of rats. 123 58

Polyphosphate glucokinase (EC 2.7.1.63, polyphosphate:glucose phosphotransferase) was covalently coupled to collagen-coated silica gel beads. The immobilized enzyme, as a packed-bed reactor, was used to determine glucose in serum and other samples. The method was based on a spectrophotometric measurement of NADPH produced by two consecutive reactions, similar to the hexokinase method. The described approach takes advantage of the greater stability of polyphosphate compared to that of ATP, the greater specificity of polyphosphate glucokinase versus that of hexokinase, and the reusability of the immobilized enzyme. Linearity, precision, and accuracy of the method were tested and found to be very good. The results were linear between 10 and 50 nmol of glucose in a 50-microliter sample and the coefficient of variation was less than 4% in five successive determinations. The recovery of glucose was about 100% after calibration of the method. The results of the measurements correlated well with those obtained with soluble polyphosphate glucokinase (r = 0.997, y = 1.036x - 0.016). The immobilized-enzyme reactor showed good operational stability during a month of use, losing about 12% of its initial activity.
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PMID:Glucose determination using immobilized polyphosphate glucokinase. 166 65

1. The maximum activities of the glycolytic enzymes hexokinase (HK) and phosphofructokinase (PFK) were measured in defatted homogenates of adipose tissue from nine homologous depots of 57 wild and captive mammals belonging to 17 species and eight orders and differing in body mass by six orders of magnitude. 2. Site-specific differences in the enzyme activities were similar in all terrestrial species and were not consistently related to adipocyte volume. 3. The specimen-mean maximum activities of HK and PFK did not correlate with body mass, body composition or natural diet. 4. When specimens of different body composition and body mass were compared, glycolytic enzyme activity per adipocyte was directly proportional to adipocyte volume. 5. Site-specific differences in collagen content of adipose tissue did not correspond to those adipocyte volume. When homologous depots of different specimens were compared, the collagen content of adipose tissue was directly proportional to body mass. 6. Adipose tissue of large cetaceans contains more collagen than predicted from the allometric equations fitted to the data from terrestrial mammals. 7. Neither the scaling of the collagen content with body mass nor the site-specific differences in its abundance are consistent with a role as protection or support for adjacent tissues. 8. There are consistent site-specific differences in the extracellular components of adipose tissue as well as in the structure and metabolism of the adipocytes. 9. Adipose tissue differs from most other tissues in that its maximum metabolic capacities do not scale to body mass. 10. Adjustment of the biochemical activity of adipose tissue to changes in body mass and body composition must depend upon neural and endocrine controls, not upon intrinsic differences in its metabolic capabilities.
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PMID:Biochemical correlates of the structural allometry and site-specific properties of mammalian adipose tissue. 256 96

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

Carbohydrate intolerance was investigated in 8 alcoholics with liver cirrhosis and in controls. Indices of carbohydrate metabolism, glucose and insulin levels after glucose loading, were compared with glucose phosphorylating (glucokinase, hexokinase) and releasing (glucose-6-phosphatase) enzymes. Comparison was also made with pericellular collagen in liver biopsies and with insulin sensitivity assessed by the euglycemic clamp technique and with conventional liver function tests including oral antipyrine test. Glucokinase activity was low or absent, hexokinase activity increased and the GK/HK ratio reduced. Glucose-6-phosphatase activity was lowered and insulin sensitivity decreased. Pericellular collagen was increased (P less than 0.001) and related to the fasting glucose (r0.593) and insulin levels (r0.526). Blood glucose was related to antipyrine metabolism (r-0.727) but not to the other liver tests. Glucose intolerance in cirrhosis seems to be associated with reduced glucose phosphorylating and liberating enzyme activities. Hyperinsulinaemia, developing secondarily, may then lead to insulin resistance.
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PMID:Carbohydrate intolerance associated with reduced hepatic glucose phosphorylating and releasing enzyme activities and peripheral insulin resistance in alcoholics with liver cirrhosis. 299 23

(i) Hepatocytes isolated from adult rats were cultured for 2 to 3 weeks on collagen in a modified, serum-free Waymouth medium containing fatty acids and varying concentrations of glucocorticoid, insulin and glucagon. (ii) In the presence of all three hormones, it was possible to maintain the content of DNA, the activity of glucokinase, pyruvate kinase, hexokinase and lactate dehydrogenase at initial levels for 2 to 3 weeks. The activity of glucokinase and pyruvate kinase was affected by the concentration of insulin. (iii) The activity of alcohol dehydrogenase was stable for 3 days and declined to about 25% of the initial level after 2 weeks of culture, irrespective of the presence of hormones. (iv) Maintenance of albumin secretion was dependent on the presence of glucocorticoid, and glucocorticoid and insulin showed an additive or, at some time points, a synergistic effect on its secretion. (v) The content of cytochrome P-450 could be kept at 65% of the initial level, provided that a relatively high concentration of dexamethasone was present (10(-6) M). (vi) In the absence of hormones, urea synthesis was 70% of initial levels throughout the experimental period. With insulin and glucocorticoid present, a high concentration of glucagon (10(-8) M) was required to maintain the synthesis of urea at this level. (vii) It is concluded that hepatocyte cultures as described in the present study may be a useful, well-defined system for long-term metabolic, pharmacologic and toxicologic studies.
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PMID:Long-term culture of hepatocytes: effect of hormones on enzyme activities and metabolic capacity. 327 89

A method has been developed for measuring the adhesion of platelets to purified collagen fibers obtained from bovine tendon. This method differs from others in that: (a) platelet adhesion is measured in the absence of platelet aggregation; (b) platelet-rich plasma collected in ACD (acid citrate dextrose) or EDTA, or washed platelets can be employed; (c) adherent platelets are enumerated directly; (d) erythrocytes and leukocytes do not adhere. Washed platelets suspended in human Ringer solution exhibit negligible adhesion (at the platelet concentrations employed) in contrast to washed platelets suspended in plasma. Addition of purified human fibrinogen (95% clottable, 2-4 mg/ml) to human Ringer solution completely restores the ability of washed platelets to adhere to collagen fibers. Albumin (fatty acid free, 50 mg/ml) is also capable of restoring adhesion. Albumin and seven other proteins at concentrations of 5-10 mg/ml, with varying molecular weights, isoelectric points, and frictional coefficients are incapable of supporting the adhesion of washed platelets. The proteins tested were human globulin, hexokinase, hemoglobin, cytochrome-C, insulin, thyroglobulin, and muramidase. Platelet adhesion is proportional to both platelet concentration and fibrinogen concentration, but is independent of temperature or glycogen stores. Modification of fibrinogen by acylation of amino groups or removal of sialic acid has no effect on its ability to support platelet adhesion. Degradation of fibrinogen with purified plasmin results in decreased support of platelet adhesion. This accompanied formation of early breakdown products with clottability ranging from 84-0%. Formation of fibrinogen degradation products was monitored by SDS-polyacrylamide gel electrophoresis of the corresponding fibrins after reduction of disulfide bonds (a method capable of distinguishing alpha-, beta- and gamma-chains). Decreased support of platelet adhesion is associated with the disappearance of intact alpha- chains and early modification of the beta-chains. Purified proteinpolysaccharide macromolecules obtained from bovine nasal and humeral cartilage, and from nucleosus pulposus are as effective as fibrinogen on a weight basis and ten to thirty times more effective on a molar basis in supporting platelet adhesion. The purified mucopolysaccharide side chains: chondroitin-4-sulfate, chondroitin-6-sulfate, and keratan-sulfate are incapable of supporting platelet adhesion.
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PMID:Biochemical and biophysical aspects of human platelet adhesion to collagen fibers. 556 92

The concentrations of ten or 12 enzymes involved in the metabolism of DNA, collagen, amino acids, or glucose have been determined in variants of human intestinal and pulmonary tissues. In comparison to nonneoplastic adult colon, normal fetal colon had elevated concentrations of thymidine kinase, peptidyl proline hydroxylase, phosphoserine phosphatase, ornithine transcarbamylase, gamma-glutamyl transpeptidase, and ornithine aminotransferase. Raised activities of the first five of these enzymes, and of hexokinase, glucose-6-phosphate dehydrogenase, and pyrroline-5-carboxylate reductase distinguishes neoplastic from nonneoplastic sections of adult colon. Study of a wide range of pulmonary specimens permitted comparisons of different types of tumors, and revealed some subtle differences between lungs of noncancer patients and nonneoplastic portions of host lungs. The concentrations of eight previously identified enzymic indicators were less in moderately or well differentiated than in poorly differentiated pulmonary adenocarcinomas. The latter differed from epidermoid carcinomas (also poorly differentiated) by containing lower concentrations of thymidine kinase (both soluble and particulate) and hexokinase.
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PMID:Enzyme activities in human fetal and neoplastic tissues. 625 48


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