Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When Cladosporium resinae is provided with n-hexadecane and glucose, n-hexadecane is used preferentially. Studies using [14C]glucose indicated that n-hexadecane did not inhibit glucose uptake but did retard oxidation of glucose to CO2 and assimilation of glucose carbon into trichloroacetic acid-insoluble material. Glucose could be recovered quantitatively from hydrocarbon-grown cells that had been transferred to glucose. Four enzymes that may be involved in glucose metabolism, hexokinase, glucose-6-phosphate dehydrogenase, glucose-phosphate isomerase, and succinate dehydrogenase, were not detected in cells grown on hexadecane but were present in cells grown on glucose. Addition of hexadecane to extracts of glucose-grown cells resulted in immediate loss of activity for each of the four enzymes, but two other enzymes did not directly involved in glucose metabolism, adenosine triphosphatase and alanine-ketoacid aminotransferase, were not inhibited by hexadecane in vitro. Cells grown on hexadecane and transferred to glucose metabolize intracellular hexadecane; after 1 day, activity of hexokinase, glucose-6-phosphate dehydrogenase, glucosephosphate isomerase, and succinate dehydrogenase could be detected and 22% of the intracellular hydrocarbon had been metabolized. Hexadecane-grown cells transferred to glucose plus cycloheximide showed the same level of activity of all the four enzymes as cells transferred to glucose alone. Thus, intracellular n-hexadecane or a metabolite of hexadecane can inthesis of those enzymes is not inhibited.
 ...
PMID:Inhibition of glucose metabolism by n-hexadecane in Cladosporium (Amorphotheca) resinae. 13 54

The interconnections between EEG, intermediary and energy metabolism of the brain cortex and CSF potassium level are studied during severe hypercapnia in anaesthetized, artificially ventilated cats. Hypercapnic animals were ventilated with 40 to 50% to CO2 in oxygen. During severe hypercapnia the EEG becomes isoelectric. The CSF potassium concentration is raised and the changes in metabolism suggest an acidosis-induced inhibition of phosphofructokinase and, probably, of hexokinase. The energy charge potential remains unchanged whereas the cortical ATP concentration increases slightly. It is assumed that the changes in P-creatine and creatine levels are related to the pH-dependency of creatine phosphokinase. Recovery animals were ventilated with 40% CO2 in O2 and subsequently with room air. After termination of CO2 inhalation the EEG reappears, the CSF potassium concentration normalizes, and the inhibition of the glycolytic enzymes disappears. The energy charge potential shows a small decrease. It is not possible to trace back the disappearance of the EEG to only one of the recorded parameters. Cortical P-creatine levels, CSF potassium concentration, changes in membrane permeability and cortical amino acid concentrations are considered in this context.
 ...
PMID:Influence of severe hypercapnia upon cerebral cortical metabolism, CSF electrolyte concentrations and EEG in the cat. 13 59

The metabolic and morphologic adaptation to physical training in skeletal muscle tissue of eleven middle-aged, physically untrained men was studied. Muscle biopsies were taken from the vastus lateralis before, after 8 weeks and after 6 months of physical training for analysis of metabolic and morphologic variables. Glucose tolerance test indicated increased insulin sensitivity after 6 months of physical training. The activities of glycogen phosphorylase, hexokinase and glucose-6-P-dehydrogenase were increased but other enzymes involved in glycogen turnover and glycolysis were unchanged after 6 months of physical traning. The activities of citrate synthase and cytochrome-c-oxidase, representing the oxidative capacity were significantly increased already after 8 weeks of physical training. The incorporation rate of palmitate-carbon into CO2 and triglycerides increased, and the incorporation rate of leucine-carbon into CO2 decreased with 6 months of physical training. The fiber diameter of both Type 1- and Type 2-fibers increased, while the mitochondrial volume increased predominantly in Type 2-fibers. Significant correlations were found between metabolic, physiologic and morphologic variables before and after physical training. The results indicate an increased oxidative capacity, mainly located to Type 2-fibers, and an increased utilization of fatty acids in response to this type of physical training.
 ...
PMID:Physical training in man. Skeletal muscle metabolism in relation to muscle morphology and running ability. 32 4

Glucose turnover was measured in normal and disbetic dogs by the dilution of glucose-1-13C and glucose-1-14C tracers infused simultaneously at constant rates. In order to quantify the stable isotope, an enzymatic assay for the analysis of glucose-1-13C was developed and evaluated. CO2 from C-1 glucose was evolved by coupling hexokinase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconic dehydrogenase activities. The 13C/12C ratio of the CO2 was measured with a high-precision magnetic-deflection double-collector mass spectrometer, and the radioactivity of 14CO2 was quantified by liquid scintillation. The ratio of 13C/12C was reproducible in assays of CO2 evolved from either naturally occurring or 13C-enriched glucose. Furthermore, systemic glucose production rates measured with 13C- and 14C-labeled tracers were similar over a wide range from 2 to 12 mg./kg.-min. Thus, glucose-1-13C may be employed as a tracer for glucose metabolism in human subjects without incurring the risk of radiation.
 ...
PMID:Estimation of glucose turnover with stable tracer glucose-1-13C. 83 67

The marked stimulatory effect of insulin on the conversion of 20 mM D-[6-14C]glucose to CO2, glyceride-glycerol, and fatty acid observed in small rat adipocytes was greatly diminished in large cells from older rats. Similarly, total glucose utilization as estimated by summing the total metabolites accumulated intracellularly plus the release of labeled CO2 and lactate was substantially lower in large cells in the presence of insulin and 5 mM labeled glucose. However, under conditions of 0.2 mM medium glucose where transport of the hexose into adipocytes is relatively more rate-limiting for subsequent metabolism, large cells actually utilized slightly greater total amounts of glucose than small cells in the presence of insulin. Increments of total glucose utilization due to both submaximal and maximal doses of insulin were similar in large and small cells incubated with a low glucose concentration. Under these conditions, conversion of labeled glucose to CO2 and fatty acid in response to insulin was somewhat diminished in large cells, while conversion to glyceride-glycerol was enhanced. The activity of the D-glucose transport system in large and small cells was estimated by monitoring initial rates and small cells was estimated by monitoring initial rates of 3-O-[3H]methylglucose uptake by a rapid filtration method. Transport system activity on a per cell basis was actually severalfold higher in large adipocytes in the basal state as well as in the presence of submaximal and maximal concentrations of insulin compared to small cells. However, the percent stimulation by insulin was less in the large cells. Uptake of 2-deoxyglucose under basal conditions and in response to insulin was also higher in large cells compared to small cells. Analysis of the accumulated label in extracts from fat cells incubated with D-[14C]deoxyglucose revealed the presence of free deoxyglucose, deoxyglucose-6-phosphate, and 6-phosphodeoxygluconate. The levels of these metabolites were significantly higher in large cells compared to small cells indicating hexokinase activity appears not to account for the defective glucose utilization in large cells at high glucose concentrations. It is concluded that (a) possible defects in insulin receptor components, the D-glucose transport system, and the coupling mechanism which links these entities do not significantly contribute to the apparent insulin-insensitivity of large fat cells and (b) the principal cellular defect which confers this blunted insulin response to large rat adipocytes involves one or more intracellular enzymes involved in glucose metabolism.
 ...
PMID:Cellular basis of insulin insensitivity in large rat adipocytes. 93 92

Photosynthetic oxygen evolution by a reconstituted chloroplast system utilising sn-phospho-3-glycerol (3-phosphoglycerate) ceases upon the addition of ribose 5-phosphate even though the presence of this metabolite permits a rapid and immediate CO2 fixation. The period of cessation is appreciable at 0.1 mM ribose 5-phosphate. It is lengthened as the amount of added ribose 5-phosphate is increased and by the addition of dithiothreitol, a known activator of ribulose-5-phosphate kinase. Ribulose 1,5-bisphosphate is without effect. A similar interruption of O2 evolution may also be brought about by the addition of ADP or by ADP-generating systems such as glucose plus hexokinase. Spectrophotometric experiments indicate that the reoxidation of NADPH in the presence of sn-phospho-3-glycerol is similarly affected. The transient inhibition by ribose 5-phosphate is not observed in the presence of an active ATP-generating system or in the presence of sufficient DL-glyceraldehyde to inhibit ribulose-5-phosphate kinase activity. It is concluded that ribose 5-phosphate inhibits photosynthetic O2 evolution by adversely affecting the steady-state ATP/ADP ratio and consequently the reduction of sn-phospho-3-glycerol to glyceraldehyde 3-phosphate. The results are discussed in their relation to ADP regulation of photosynthetic carbon assimilation and metabolite transport.
 ...
PMID:Transient inhibition by ribose 5-phosphate of photosynthetic O2 evolution in a reconstituted chloroplast system. 126 44

The consumption of glucose by trypanosomatid protozoa such as Trypanosoma brucei, Trypanosoma cruzi, Leishmania spp., and Crithidia spp. is characterized by the excretion of reduced products such as succinate, pyruvate, ethanol, L-alanine, or lactate (depending on the species) not only in anaerobiosis, but also under aerobic conditions. The "aerobic fermentation" of glucose is accompanied by a complete lack, or even a reversal, of the Pasteur effect. This peculiar catabolism is mediated by a so-far unique compartmentation of the glycolytic enzymes, most of which are placed in an organelle called the glycosome; by an almost complete lack of inhibitory controls at the level of hexokinase and phosphofructokinase; and by a central role of CO2 fixation through the reaction catalyzed by phosphoenolpyruvate carboxykinase. The production of fermentative products seems to be due to a relative inefficiency of the respiratory chain, which lacks NADH dehydrogenase and the first phosphorylation site and preferentially uses succinate as substrate.
 ...
PMID:Aerobic fermentation of glucose by trypanosomatids. 139 37

Glucose metabolism has been studied in Salmo trutta red blood cells. From non-metabolizable analogue (3-O-methyl glucose and L-glucose) uptake experiments it is concluded that there is no counterpart to the membrane transport system for glucose found in mammalian red blood cells. Once within the cells, glucose is directed to CO2 and lactate formation through both the Embden-Meyerhoff and hexose monophosphate shunts; lactate appears as the most important end-product of glucose metabolism in these cells. From experiments under anaerobic conditions, and in the presence of an inhibitor of pyruvate transfer to mitochondria, most of the CO2 formed appears to derive from the hexose monophosphate pathway. Appreciable O2 consumption has been detected, but there is no clear relationship between this and substrate metabolism. Key enzymes of glucose metabolism, hexokinase, fructose-6-phosphate kinase and, probably, pyruvate kinase are out of equilibrium, confirming their regulatory activity in Salmo trutta red blood cells. The presence of isoproterenol, a catecholamine analogue, induces important changes in glucose metabolism under both aerobic and anaerobic conditions, and increases the production of both CO2 and lactate. From the data presented, glucose appears to be the major fuel for Salmo trutta red blood cells, showing a slightly different pattern of glucose metabolism from rainbow trout red blood cells.
 ...
PMID:Glucose metabolism by trout (Salmo trutta) red blood cells. 140 38

Spirochaeta thermophila RI 19.B1 (DSM 6192) fermented glucose to lactate, acetate, CO2, and H2 with concomitant formation of cell material. The cell dry mass yield was 20.0 g/mol of glucose. From the fermentation balance data and knowledge of the fermentation pathway, a YATP of 9.22 g of dry mass per mol of ATP was calculated for pH-uncontrolled batch-culture growth on glucose in a mineral medium. Measurement of enzyme activities in glucose-grown cells revealed that glucose was taken up by a permease and then subjected to ATP-dependent phosphorylation by a hexokinase. Glucose-6-phosphate was further metabolized to pyruvate through the Embden-Meyerhof-Parnas pathway. The phosphoryl donor for phosphofructokinase activity was PPi rather than ATP. This was also found for the type strain of S. thermophila, Z-1203 (DSM 6578). PPi was probably formed by pyrophosphoroclastic cleavage of ATP, with recovery of the resultant AMP by the activity of adenylate kinase. All other measured kinase activities utilized ATP as the phosphoryl donor. Pyruvate was further metabolized to acetyl coenzyme A with concomitant production of H2 and CO2 by pyruvate synthase. Lactate was also produced from pyruvate by a fructose-1,6-diphosphate-insensitive lactate dehydrogenase. Evidence was obtained for the transfer of reducing equivalents from the glycolytic pathway to hydrogenase to produce H2. No formate dehydrogenase or significant ethanol-producing enzyme activities were detected.
 ...
PMID:Glucose catabolism by Spirochaeta thermophila RI 19.B1. 155 64

It has been shown previously that glucose-induced insulin release is completely absent in rat pancreatic islets that had been cultured for 1 day at low glucose (1 mM) and that it is restored by culturing islets for a 2nd day at high (20 mM) glucose (MacDonald, M. J., Fahien, L. A., McKenzie, D. I., and Moran, S. M. (1991) Am. J. Physiol. 259, E548-E554). It has been suggested that the incapacitation of glucose's insulinotropism is due to down-regulation of the synthesis of enzymes that process glucose's metabolic signal for insulin release. In the current study, results of metabolic, enzymic, and molecular biologic experiments were each consistent with (an) intramitochondrial site(s) of down-regulation in islets cultured at low glucose. Glucose metabolism was inhibited 80% in islets cultured at 1 mM glucose. The suppression of release of 14CO2 from [6-14C]glucose greater than from [U-14C]glucose greater than [3,4-14C]glucose greater than from [1-14C]glucose in islets cultured at low glucose indicated a mitochondrial site of down-regulation because C-6 of glucose can only be converted to CO2 in the citric acid cycle, whereas C-1 can be released as CO2 in the 6-phosphogluconate dehydrogenase [corrected] reaction, and C-6 of glucose dwells in the citric acid cycle longer than carbons 2-5 of glucose. Since carbons 3 and 4 of glucose can be decarboxylated in the pyruvate dehydrogenase reaction, incomplete suppression of CO2 formation from these carbons is consistent with suppression of pyruvate carboxylation as well as decarboxylation. Formation of 3HOH from [5-3H]glucose was equal in the two groups of islets, indicating that glycolysis as far as phosphoenolpyruvate was intact. This idea was supported by assays which showed that activities of enzymes of the glycolytic pathway between glucokinase/hexokinase and pyruvate kinase were equal in both types of islets. Additional studies indicated that regulation by glucose was at transcription of genes coding for some mitochondrial enzymes. Glucokinase, malic enzyme, and fumarase mRNAs were not affected by glucose, whereas the pyruvate dehydrogenase E1 alpha subunit and pyruvate carboxylase mRNAs were decreased 85-90% in islets cultured at 1 mM glucose. Pyruvate dehydrogenase enzyme activity was decreased to a similar extent in these islets. About 24 h was required for maximal (de)induction of pyruvate dehydrogenase E1 alpha and pyruvate carboxylase mRNAs, and the amounts of transcripts were proportional to the concentrations of glucose between 1 and 20 mM.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Pyruvate dehydrogenase and pyruvate carboxylase. Sites of pretranslational regulation by glucose of glucose-induced insulin release in pancreatic islets. 193 63


1 2 3 4 5 6 Next >>