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)

Histologic investigations together with histochemical and photometric measurements of enzyme activities were performed in retina of rabbits, whose blood supply had been totally interrupted for 1h. A retinal edema developed affecting the internal layers between the inner limiting membrane and the internal plexiform and ganglion cell layer. Although this edema was quite remarkable at the posterior pole of the eye, it diminished toward the periphery, disappearing near the ora serrata. The activities of the following enzymes were investigated: hexokinase, glucose 6-phosphate dehydrogenase, aldolase, glyceraldehydephosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, ATPase, and phosphorylase. The most striking finding was the total disappearance of phosphorylase activity under pressure ischemia. ATPase and aldolase showed a decreased activity in the ischemic retina, and malate dehydrogenase a slightly diminished one. Concerning the other enzymes, no significant differences between normal and ischemic retina were observed.
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PMID:Enzymologic and histologic investigations in normal and pressure-ischemic retina of rabbits. 108 79

The dynamics of glycolysis and glycogenolysis in the postnatal period, determined from the accumulation of lactate in the homogenate of the heart muscle, indicates that the glycolytic activity begins to subside right after the birth and becomes constant after a lapse of 15-20 days. The activity of the phosphorylase, phosphohexoisomerase, enolase and pyruvate-kinase in the heart muscle extract was found to remain virtually unchanged. Some decline is noted in the activity of the aldolase and hexokinase, while that of the phosphofructokinase and lactate-dehydrogenase rises by 50-60 per cent. These data suggest that in the early ontogenesis the increasing capacity of the mitochondrial system in the heart muscle is paralled by an adjustable conditioned inhibition of the glycolytic phosphorylation, with concurrently rising activity of the phosphofructokinas and, consequently, also of the potential capacity of glycolysis and glycogenolysis.
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PMID:[Dynamics of carbohydrate metabolism in the heart muscle in early ontogenesis]. 116 19

In the subcommissural organ (SCO) of the guinea pig, rat, golden hamster, and mouse the activity and distribution of enzymes related to the energy-supplying metabolism and of some marker enzymes of different cell organelles have been investigated by means of mostly modified histochemical methods. The results were compared with findings in the ciliated ependyma of the ventricular wall and with those in the ependyma of the choroid plexus of the third ventricle. In the ependymal part of the SCO only a moderate activity of hexokinase is observed in its specialized columnar cells whereas a high activity is present both in the ciliated ependyma and the choroid plexus. - The staining pattern of glucose-6-phosphatase is similar to that of hexokinase but this enzyme is found is the SCO only. - Likewise hexokinase, glycogen granules and enzymes related to glycogen metabolism (phosphoglucomutase, uridine-diphosphoglucose pyrophosphorylase, glycogen synthetase and phosphorylase) are regularly found most numerous and active in the nuclear and supra-nuclear area of the ependymal part. These enzymes are less active in both the other ependymal regions. - Uridine-diphosphoglucose dehydrogenase could not be demonstrated in the SCO. The NADP-linked enzymes of the pentose phosphate shunt, glucose-6-phosphate and 6-phosphogluconate dehydrogenase, show a moderate activity which decreases also from the nuclear towards the apical area of the ependymal cells of the SCO. Enzymes of the glycolytic pathway, such as glucosephosphate isomerase, fructose-6-phosphate kinase, fructose-I,6-diphosphate aldolase, glyceraldehyde-3-phosphate and lactate dehydrogenase, are highly active in the SCO and are located mainly in the supranuclear area, too. Fructose-1,6-diphosphatase could not be demonstrated thus indicating that in the SCO the pathway is most probably only glycolytic but not gluconeogenetic. Compared to the ependyma of the ventricular wall and of the choroid plexus, in the SCO the M type subunits of lactate dehydrogenase predominate. Glycolytic enzymes are also very active in the choroid plexus but less in the ciliated ependyma. Compared to the ciliated ependyma and especially to the ependyma of the choroid plexus, the activities of enzymes which are only present in mitochondria (NAD-linked isocitrate dehydrogenase, succinate dehydrogenase, NAD-linked malate dehydrogenase after preextraction, cytochrome oxidase, 3-hydroxybutyrate and glycerolphosphate and glutamate dehydrogenase) are relatively low. Mitochondria are accumulated near the superior pole of the nuclei as well as in the most apical part of the ependymal cells. - The staining pattern of NADP-linked isocitrate and malate dehydrogenase as well as of NADH dehydrogenase suggests that these enzymes are localized both in and out of mitochondria. The extramitochondrial activity of the first two enzymes might be localized in the cytosol. The extramitochondrial activity of NADH dehydrogenase might be localized in the endoplasmic reticulum...
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PMID:Enzymatic organization of the subcommissural organ. 123 49

Detailed histochemical studies have been conducted on the distribution of various enzymes such as thiamine pyrophosphatase, alpha-glucan phosphorylase, hexokinase, glucose-6-phosphate dehydrogenase, aldolase, lactate dehydrogenase and succinate dehydrogenase in various components of the nucleus Edinger-Westphali, nucleus n. oculomotorii, nucleus ruber and nucleus niger of healthy adult male Wistar strain rats. The thiamine pyrophosphatase reaction showed the morphological patterns of the Golgi apparatus characteristic for each nucleus. The Golgi apparatus was well developed in the nucleus Edinger-Westphali, composing a network of highly fenestrated plates in the nucleus n. oculomotorii and nucleus ruber, and a simple network in the nucleus niger. These results indicate that the former three nuclei need a rich energy supply and argue against the possibility that the four nuclei have a secretory role. The neurons of the nucleus Edinger-Westphali may derive their energy mainly from glucose of the circulating blood, but glial cells may serve as energy donators to the neurons in the pars compacta of the nucleus niger, and the neurons of the other nuclei may derive energy from both sources. These conclusions are consistent with the morphological patterns of the Golgi apparatus.
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PMID:Histochemical studies on the morphology of the Golgi apparatus and on the enzymes of carbohydrate metabolism in various nuclei of the rat mesencephalon. 124 52

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

Selected enzymes of energy metabolism were measured in random individual fibers of soleus and tibialis anterior (TA) muscles from rats exposed for 2 wk to spaceflight (F) aboard COSMOS 2044 or tail suspension (T) and from synchronous controls. Average size of soleus fibers (dry weight per unit length) was reduced 37% in F and T fibers; there was little change in TA fibers. Enzyme changes were more pronounced in soleus than in TA fibers. Three enzymes characteristic of fast-twitch muscles, pyruvate kinase, glycerol-3-phosphate dehydrogenase, and 1-phosphofructokinase, were elevated in F and T soleus fibers, but changes in phosphofructokinase were not statistically significant. 3-Ketoacid-CoA transferase, characteristic of slow-twitch muscles, did not change significantly in either F or T fibers. Hexokinase, usually moderately higher in slow- than in fast-twitch muscles, increased markedly in both F and T fibers. In TA fibers analyzed for hexokinase, malate dehydrogenase, phosphohexoisomerase, and pyruvate kinase, only hexokinase and malate dehydrogenase showed significant changes. Hexokinase increased 83% in one of two T muscles. Enzyme data for TA fibers typed by myosin adenosinetriphosphatase were more informative: phosphofructokinase, phosphorylase, and glycerol-3-phosphate dehydrogenase were increased in type IIb fibers of either F or T muscles or both. Malate dehydrogenase was not changed in fibers of any type in either F or T muscle.
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PMID:Effects of microgravity and tail suspension on enzymes of individual soleus and tibialis anterior fibers. 138 50

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

1. Replacement of fetal calf serum and chicken embryo extract by Ultroser G and rat brain extract during the proliferation phase resulted in a higher maturation grade of cultured rat muscle cells after 7 days of differentiation, on base of the percentage of the muscle specific isoenzyme of creatine kinase (CK-MM). 2. Furthermore, the activities of creatine kinase, citrate synthase, cytochrome c oxidase and hexokinase were significantly higher. 3. Compared to the enzyme activities in m. quadriceps of 10 day-old rat and m. quadriceps, m. soleus and m. extensor digitorum longus of young adult rats, the metabolic capacity of cultured myotubes most closely resembles that of the first muscle. 4. Paralysis with tetrodotoxin caused a slight decrease of the creatine kinase activity and the percentage of CK-MM of cultured myotubes and an increase of the activities of hexokinase, phosphorylase and AMP deaminase. 5. Electrical stimulation performed at different frequencies and time periods had no effect on the enzyme activities of cultured rat muscle cells. 6. Only the AMP deaminase activity was decreased after intense electrical stimulation.
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PMID:Effects of growth medium, electrical stimulation and paralysis on various enzyme activities in cultured rat muscle cells. Comparison with activities in rat muscles in vivo. 159 50

This study compared the exercise catecholamine and metabolic responses to a caffeine challenge in trained subjects before and after a 6-wk period of increased caffeine ingestion. Trained subjects (n = 6) were challenged with 500 mg of caffeine followed by prolonged exercise before and after 6 wk of increased caffeine ingestion (500 mg ingested before each daily run). A control group (n = 6) of trained subjects followed the same protocol except for caffeine ingestion. Acute caffeine ingestion resulted in increased plasma epinephrine and decreased respiratory exchange ratio (RER) during exercise. After 6 wk of caffeine supplementation, the epinephrine response to exercise or caffeine plus exercise was decreased, although the latter still resulted in a lower RER value compared with exercise without caffeine ingestion. Activity of key metabolic enzymes (hexokinase, citrate synthase, phosphorylase, and 3-hydroxyacyl-coenzyme A dehydrogenase) from biopsies of the gastrocnemius showed no response to 6 wk of this increased adrenergic receptor stimulation and, on the basis of the lower RER, enhanced fat metabolism. This study suggests that caffeine ingestion by trained subjects causes increases in plasma epinephrine and reduces the RER during exercise. However, habitual stimulation results in a general dampening of the epinephrine response to caffeine or exercise. There was no indication that increased adrenergic stimulation and fat oxidation caused any adaptation in the activity of metabolic enzymes.
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PMID:Acute and habitual caffeine ingestion and metabolic responses to steady-state exercise. 159 18

On the basis of the percentage creatine kinase-MM, human skeletal muscle cells cultured on growth and differentiation media containing the serum substitute Ultroser G reach a significantly higher maturation grade after 7 days of differentiation than cells cultured on serum-containing media. They also remain viable for longer periods. The myotubes are much longer, their nuclei are often localized in rows on the periphery, and they show cross-striation more frequently. The activities of creatine kinase, citrate synthase, cytochrome c oxidase, AMP deaminase, and phosphorylase are significantly higher. Extending the differentiation period to 3 weeks increases the maturation grade of the cultures and the activities of all the enzymes mentioned before, except phosphorylase. A correlation exists between the enzyme activities and the maturation grade of the muscle cells. The content of fatty acid-binding protein also increases significantly with the maturation grade in contrast to the palmitate oxidation rate. The AMP deaminase and creatine kinase activity and the percentage MM-type remain lower in cultured cells than in adult muscle and the hexokinase activity remains higher, but the other enzyme activities become comparable after 20 days of differentiation. The myotubes, derived from Ultroser G-containing culture media, show spontaneous contractions after 12 days and cross-striation after 20 days when immunostained for the M-subunit of creatine kinase. These cells possess clusters of acetylcholine receptors, but aggregation of desmin at the site of the clusters was never detectable. The possibility of cultivating muscle cells with a predictable maturation grade allows the study of muscle development and muscular diseases caused by differentiation defects or by deficiency of a maturation-dependent (iso)enzyme.
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PMID:The biochemical and structural maturation of human skeletal muscle cells in culture: the effect of the serum substitute Ultroser G. 164 54


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