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)

The cerebral metabolic effects of 2.5, 5, 7.5, 10, 20, 30 and 60 min exposure to 1% CO were studied in lightly anesthetized rats by measurement of cerebral cortical contents of selected glycolytic and citric acid cylce intermediates, as well as tissue energy phosphates. The initial change in the glycolytic sequence occurred at 2.5 min with decreases in tissue glucose and glucose-6-phosphate and increases in fructose-1-6-diphosphate which indicated an activation of phosphofructokinase and hexokinase. The "crossover" pattern between glucose-6-phosphate and fructose-1,6-diphosphate was present at 5, 7.5 and 10 min, but not at 20, 30 and 60 min and thus confirmed previous observations that detection of phosphofructokinase activation in acute unifactorial cerebral hypoxia requires tissue study during the early phases of the experimental exposure. The initial activation of phosphofructokinase occurred in the absence of detectable changes in the tissue content of ATP, ADP, AMP or phosphocreatine and therefore suggested that an imbalance of tissue energy homeostasis is not a prerequisite for the activation of glycolysis in CO intoxication. One percent CO resulted in an increasing malate/oxaloacetate ratio at 5 min, followed by a decrease in alpha-ketoglutarate and aspartate at 7.5 min which suggested a shift in the aspartate aminotransferase reaction towards the replenishment of oxaloacetate removed via the malate dehydrogenase reaction. Subsequent increases in alpha-ketoglutarate at 10, 20, 30 and 60 min were associated with increases in alanine, indicating a contributing role for a secondary shift of the alanine aminotransferase reaction in the replenishment of alpha-ketoglutarate. A comparison of the CO induced changes in the glycolytic and citric acid cycle pathways with those seen in acute hypoxemia indicates no basic qualitative differences in the metabolic responses of brain tissue to the two conditions.
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PMID:Cerebral carbohydrate metabolism during acute carbon monoxide intoxication. 1 62

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.
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PMID:Inhibition of glucose metabolism by n-hexadecane in Cladosporium (Amorphotheca) resinae. 13 54

Hepatic carbohydrate metabolism in genetically diabetic mice (db/db) and their normal littermates has been studied. In db/db mice, body water was below normal and declined with age. The liver of db/db mice was abnormally large in relation to the metabolic mass of the body at all ages studied. In db/db mice, hepatic glycogenolysis, glycogen synthesis, glycogen synthetase, and phosphorylase were markedly increased. Gluconeogenesis from alanine or lactate in perfused livers of db/db mice was greater than normal per 100 g body water. Activities of fructose-1, 6-biophosphatase, glucose-6-phosphatase, glucokinase + hexokinase, and pyruvate kinase were elevated in livers of db/db mice. Diabetic mouse livers perfused with lactate showed a markedly reduced concentration of P-enolpyruvate and clear "forward crossover" between fructose-1, 6-P2 and fructose-6-P. In vivo glucose clearance, measured with [3-3H]glucose, in db/db mice was 170% that of normal mice. Data presented indicate that in livers of db/db mice: 1) glucose production is elevated prior to hyperglycemia, 2) glycogen turns over more rapidly, and 3) glycolytic and gluconeogenic enzymes are elevated paradoxically. These abnormalities are discussed from the viewpoint of their etiology.
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PMID:Hepatic metabolism of genetically diabetic (db/db) mice. I. Carbohydrate metabolism. 17 48

A neutral SH-dependent proteinase was isolated from bovine spleen by a slight modification of the previous method (1) and its action on some natural and synthetic substrates was studied. The activity of the enzyme was increased 2000--2500-fold as compared to that of the original extract. The enzyme hydrolyzed various histones (H1, H2a, H2b, H3), casein and protamine but did not split hemoglobin, serum albumin and 14C-tryptophane-labelled total protein from chicken embryos. The enzyme possessed neither collagenolytic nor elastase activity; it did not inactivate aldolase, hexokinase, glyceraldehyde phosphate dehydrogenase and glucose-6-phosphate dehydrogenase, which makes the enzyme different from cathepsin B1 and some other previously described proteinases. The enzyme did not split BAPA, BAEE, ATEE, Boc-Ala-ONP, Leu-beta-NA and some other peptides. The molecular weight of the enzyme was found to be about 15 000.
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PMID:[Isolation and properties of neutral SH-dependent proteinase from bovine spleen]. 43 66

This report summarizes a one year evaluation of Abbott's ABA 100, with respect to mechanical parts (syringe plates, precision and linearity of photometry, band width of several filters, multicuvet precision, temperature control) and the reliability of several methods (endpoint procedures: determination of the glucose concentration with hexokinase- and the glucose dehydrogenase method, and of the protein concentration; enzyme activities: alanine and aspartate aminotransferase, creatine kinase, alkaline phosphatase). The critical batch size was estimated as an indicator of economy (about 40 samples per day for the glucose concentration). Various aspects of the instrument are discussed with respect to its use in clinical chemistry.
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PMID:Evaluation of the Abbott Bichromatic Analyzer 100 (A proposal for an evaluation scheme). 95 29

In a model system consisting of highly coupled rat liver mitochondria respiring in the presence of substrate, pyruvate kinase, phosphoenolpyruvate, ATP, hexokinase and glucose, the increase in the mitochondrial concentration results in a progressive decrease in the activity of pyruvate kinase. These results are in accord with a role of pyruvate kinase as a determinant of glycolytic activity by competing with mitochondrial oxidative phosphorylation for the available ADP. The addition of adequate amounts of the amino acids, cysteine, alanine and phenylalanine, known as inhibitors of pyruvate kinase, to living Ehrlich ascites tumor cell suspensions results in a stimulation of the respiratory rate and in a decrease of the glycolytic rate of the cells. Concomitant with these changes, there is an accumulation of intracellular phosphoenolpyruvate and ADP, and a decrease in pyruvate and ATP. These results provide additional evidence for paying attention to pyruvate kinase as another key enzyme whose properties and activities may be major determinants for the control of glycolysis and the Crabtree and Pasteur effects of tumor cells.
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PMID:Stimulation of tumor-cell respiration by inhibitors of pyruvate kinase. 117 5

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.
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PMID:Aerobic fermentation of glucose by trypanosomatids. 139 37

Despite the extensive sequence similarity between the N- and C-terminal halves of the 100-kDa molecular weight mammalian hexokinases (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1), reflecting their evolutionary origin by duplication and fusion of a gene coding for a smaller ancestral hexokinase, there is evidence for a functional division, with the C-terminal domain retaining a catalytic role while the N-terminal domain serves a regulatory function [binding of the product inhibitor, glucose 6-phosphate) (Glc-G-P)]. Conversion of Ser603 to Ala in the C-terminal domain of rat Type I hexokinase, expressed in COS-1 cells, resulted in drastic reduction of catalytic activity; Ser603 is analogous to Ser158, a residue of critical catalytic importance in the homologous yeast hexokinase. In contrast, conversion of Ser155 to Ala in the N-terminal domain (analogous to Ser603 in the C-terminal domain) of rat Type I hexokinase had no effect on catalytic activity or on inhibition of the enzyme by the Glc-6-P analog, 1,5-anhydroglucitol-6-P. Immunoreactivity with monoclonal antibodies recognizing conformationally sensitive epitopes was not affected, indicating that neither mutation resulted in gross structural perturbation. These results are consistent with the assignment of catalytic function, involving Ser603, to the C-terminal domain, and demonstrate that the analogous Ser155 is not critical for either catalytic or regulatory function. The Type I isozyme, expressed in COS-1 cells, retained the ability to bind to mitochondria in a Glc-6-P-sensitive manner, as previously found with the enzyme isolated from mammalian tissues.
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PMID:Functional consequences of mutation of highly conserved serine residues, found at equivalent positions in the N- and C-terminal domains of mammalian hexokinases. 152 37

1. The metabolism of glucose and glutamine was studied in the small intestine and the colon of rats after 4-5 weeks of hypothyroidism. 2. Hypothyroidism resulted in increases in the plasma concentrations of ketone bodies (P less than 0.05), cholesterol (P less than 0.001) and urea (P less than 0.001), but decreases in the plasma concentrations of free fatty acids (P less than 0.05) and triacylglycerol (P less than 0.001). These changes were associated with decreases in the plasma concentrations of total tri-iodothyronine, free tri-iodothyronine, total thyroxine and free thyroxine. 3. Hypothyroidism decreased both the DNA content (by 30.5%) and the protein content (by 23.6%) of intestinal mucosa, with the protein/DNA ratio remaining unchanged. The villi in the jejunum were shorter (P less than 0.05) and the crypt depth was decreased by about 26.5% in hypothyroid rats. 4. Portal-drained visceral blood flow showed no marked change in response to hypothyroidism, but was accompanied by decreased rates of extraction of glucose, lactate and glutamine and release of glutamate, alanine and ammonia. 5. Enterocytes and colonocytes isolated from hypothyroid rats showed decreased rates of utilization and metabolism of glucose and glutamine. 6. The maximal activities of hexokinase (EC 2.7.1.1), 6-phosphofructokinase (EC 2.7.1.11), pyruvate kinase (EC 2.7.1.40), citrate synthase (EC 4.1.3.28), oxoglutarate dehydrogenase (EC 1.2.4.2) and phosphate-dependent glutaminase (EC 3.5.1.2) were decreased in intestinal mucosal scrapings from hypothyroid rats. Similar decreases were obtained in colonic mucosal scrapings (except for citrate synthase and oxoglutarate dehydrogenase) from hypothyroid rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of hypothyroidism on glucose and glutamine metabolism by the gut of the rat. 165 36

Soluble rat liver glucokinase was expressed at high levels at 22 degrees C in the BL21(DE3)pLysS strain of Escherichia coli. Aspartate-211 of yeast hexokinase has been implicated as a catalytic residue from crystallographic data. The corresponding residue in rat liver glucokinase, aspartate-205, was mutated to alanine and the expressed mutant had 1/500th of the activity of the wild type, with no change in the Km values for glucose or ATP. The results support a role for this residue as a base catalyst in the glucokinase reaction and, most probably, a similar role in the reactions of all members of the hexokinase family.
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PMID:Expression and site-directed mutagenesis of hepatic glucokinase. 185 32


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