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

---

Query: EC:2.7.1.1 (hexokinase)
5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sex differences in development of spontaneous liver tumors were studied in mice of CBA strain. Content of mitochondrial proteins, activities of cytochrome oxidase, glucokinase, hexokinase as well as subcellular distribution of hexokinase were also studied in primary hepatomas and in normal liver tissue of the mice of CBA and C3HA strains. Liver tumors occurred in males of CBA strain 7-fold more frequently than in females. Activities of hexokinase, glucokinase, cytochrome oxidase and content of mitochondrial proteins were distinctly alterep both in primary spontaneous hepatomas and in transplantable strains. But, contrary to the transplantable tumors, in spontaneous hepatomas hexokinase, associated with mitochondria, was not found. Decrease in activities of glucokinase and cytochrome oxidase was observed at the early stages of development of CBA strain in males as compared with females of CBA and males of C3HA strains, i.e. distinct decrease in several functional patterns of liver tissue was observed. Subcutaneous administration of orthoamine azotoluene into mice of the C3HA strain caused alteration in activity of these enzymes from liver tissue, which was typical for hepatomas, already at the early steps of development.
...
PMID:[Biochemical features of the liver of high and low cancer mouse strains and primary spontaneous hepatomas]. 21 May 88

The noradrenaline and glycogen contents as well as hexokinase, glucokinase and glucose-6-phosphatase activities were determined in normal, embryonic and partially denervated (bilateral dissection of the Nervus splanchnicus or Nervus vagus) rat liver and in two transplantable hepatomas. In embryonic liver and hepatomas a strong decrease or complete loss of noradrenaline and glycogen levels and glucokinase and glucose-6-phosphatase activities is demonstrable as compared to the livers of adult animals, while the hexokinase activity is enhanced. Following bilateral splanchnicotomy the glycogen content and hexokinase activity are enhanced; the glucose-6-phosphatase activity is reduced, and the liver does not contain any noradrenaline. Bilateral vagotomy causes decrease of the glycogen content, of the hexokinase and glucokinase activities and an enhancement of glucose-6-phosphatase activity. The results lend support to the idea of antagonistic action of the sympathetic and parasympathetic nervous systems upon several partial reactions of carbohydrate metabolism of liver. In addition, it can be assumed that the alterations of the carbohydrate metabolism demonstrable in hepatomas as compared to normal liver are not solely attributable to disturbance or breakdown of the nervous regulation.
...
PMID:[Noradrenaline and glycogen content and the activity of several enzymes of carbohydrate metabolism in normal, embryonic, and partly denervated livers and in hepatomas of the rat]. 21 Jun 7

The conversion of glucose into glucose 6-phosphate in an extract of isolated rat hepatocytes incubated in the presence of MgATP was studied spectrophotometrically at 340nm and also by a radiochemical procedure based on the release of (3)H from [2-(3)H]glucose. Both methods gave similar results. The glucose-saturation curve was sigmoidal and the shape of this curve was not influenced by the ionic composition of the incubation medium. The activity at 0.5mm-glucose was only 1-2% of V(max.), indicating a virtual absence of low-K(m) hexokinase in the preparation. The radiochemical method was also used for the determination of glucose phosphorylation by intact hepatocytes. The glucose-saturation curve was also markedly sigmoidal, but the s(0.5) (substrate concentration at half-maximal velocity) and the Hill coefficient were larger than in extracts of hepatocytes. These two parameters became smaller when cells were incubated in a medium in which Na(+) ions were replaced by K(+) ions. The increased rate of phosphorylation at low glucose concentration in a K(+) medium was accompanied by an increased rate of metabolite recycling between glucose and glucose 6-phosphate and also by an increased uptake of glucose. In both media phosphorylation of glucose was inhibited co-operatively by N-acetylglucosamine. Calculations indicate that this inhibition would reach 100% at saturation of the inhibitor, although at lower concentrations of N-acetylglucosamine it was smaller than expected from the known K(i) of N-acetylglucosamine for glucokinase. The rate of phosphorylation of glucose was proportional to the amount of glucokinase in hepatocytes from newborn rats and in conditions such as starvation and diabetes in which the total amount of glucokinase in the liver is decreased. In the same conditions, glucose 6-phosphatase activity was either normal or increased. It is concluded that the phosphorylation of glucose in isolated hepatocytes follows sigmoidal kinetics, which can be explained by the activity of glucokinase alone with no participation of low-K(m) hexokinase or of glucose 6-phosphatase.
...
PMID:Phosphorylation of glucose in isolated rat hepatocytes. Sigmoidal kinetics explained by the activity of glucokinase alone. 21 56

A systematic study of adenosine triphosphate (ATP)-dependent hexose kinases among microorganisms has been undertaken. Sixteen hexose kinases of five major types were partially purified from 12 microorganisms and characterized with respect to specificity for sugar and nucleotide substrates and Michaelis constants for the sugar substrates. Glucokinase activities that phosphorylate glucose and glucosamine are inhibited by N-acetyl-glucosamine and xylose, were found to be present in the non-sulphur photosynthetic bacteria Rhodospirillum rubrum, the blue-green algae Anacystis montana, and the protists Chlorella pyrenoidosa and Chlamydomonas reinhardtii (green algae), Hypochytrium catenoides (Hypochytridiomycete) and Saprolegnia Iitoralis (Oomycete). The myxobacteria Stigmatella aurantiaca contains a glucokinase activity with a different specificity pattern. Anacystis and Chlorella, besides their glucokinase activities, contain highly specific fructokinases, although that from Anacystis can also phosphorylate fructosamine; fructokinase from Anacystis has a molecular weight of 20 000, and exhibits a sigmoidal saturation curve for ATP when the Mg2+/ATP ratio is 2; this curve is transformed to a Michaelian one when under the same conditions an excess of Mg2+ (5 mM) is added. Saprolegnia however, besides the glucokinase, contains a mannofructokinase activity that phosphorylates mannose (Km 0.06 mM) and fructose (1 mM). On the other hand, hexokinase, a low specificity enzyme, was detected in the protist Allomyces arbuscula (Chytridiomycete) and in fungi Mucor hiemalis and Phycomyces blakesleeanus (Zygomycetes), and Schizophyllum commune (Basidiomycete). Schizophyllum contains a glucomannokinase activity together with hexokinase activity. The pattern of distribution of ATP-dependent hexose kinases among microorganisms seems to parallel that reported for biosynthetic pathways for lysine. The correlation with other biochemical parameters is also considered.
...
PMID:Distribution of adenosine 5'-triphosphate (ATP)-dependent hexose kinases in microorganisms. 21 81

During the first 72 h after 67% partial hepatectomy of female Wistar rats (160 g) the specific activities [mumol X min-1 X (g liver)-1] of the glucogenic glucose-6-phosphatase and fructose-bisphosphatase and of the glycolytic hexokinase and 6-phosphofructokinase remained essentially constant. However, the activity of the glycolytic pyruvate kinase (L- plus M2-type) was decreased slightly and that of glucokinase was decreased markedly to below 30%, while the glucogenic phosphoenolpyruvate carboxykinase was increased to over 200%. Between 10 and 40 h after partial hepatectomy, when the proliferation started in the periportal area, a shift of the glucogenic glucose-6-phosphatase-rich zone from its normal periportal to an intermediate or even perivenous position was observed histochemically. After 48 h, when the proliferation was no longer restricted to the periportal zone, the normal glucose-6-phosphatase zonation (as before partial hepatectomy) was restored. Glycogen was degraded rapidly during the first 4 h after operation; it was later repeatedly resynthesized and degraded in correlation with the feeding rhythm of the animals. The zonation of glycogen metabolism was in accord with the observed zonation of glucose-6-phosphatase.
...
PMID:Increase of the gluconeogenic and decrease of the glycolytic capacity of rat liver with a change of the metabolic zonation after partial hepatectomy. 21 1

Activities of hexokinase, glucokinase, cytochrome oxidase as well as amount of mitochondrial protein and subcellular distribution of hexokinase were studied in rat liver tissue after administration of acetyl aminofluorene and diethyl nitrosamine. Activity of the enzymes was altered in the same direction both in the primary induced hepatomas and in transplantable tumors of liver tissue. Glucokinase was not found but the fraction of hexokinase bound to mitochondrial membranes was observed in all the primary hepatomas studied; in this property the tumors resembled the embryonal liver tissue, various tissues of mature animals and transplantable hepatomas. This pattern of distribution of the enzymes reflects biochemical and functional disdifferentiation of the hepatomas. Properties of the bound hexokinase from the hepatoma were similar to those of the enzyme from embryonal liver tissue and, hence, they were distinct as compared with the enzymatic properties of hexokinase in the transplantable hepatomas.
...
PMID:[Activity of the key glycolysis and respiration enzymes in the rat liver in chemical carcinogenesis]. 22

Hyperinsulinemia was produced in fetal rhesus monkeys for 21 days in the last third of gestation by subcutaneous pork insulin injected at 19 U a day. Plasma insulin concentrations in treated fetuses (N = 4) were 3525 microU/ml. There was no difference in paired pre- and post-treatment fetal plasma glucose concentration. Activity of the hepatic enzymes that promote glucose utilization (glucokinase and hexokinase) and glycolysis (phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase) was unaffected. Similarly, glycogen metabolism enzymes (active and inactive synthase and phosphorylase) were unaltered. Two gluconeogenic enzymes (PEPCK and glucose-6-phosphatase) were diminished in the treated group compared with controls. Fetal hyperinsulinemia enhanced lipogenic and NADPH-producing enzyme activities, as evidenced by a twofold increase in fatty acid synthase and in citrate cleavage enzyme activity. Malic enzyme was absent. Hyperinsulinemia with euglycemia (1) increases the activity of enzymes that participate in lipogenesis, (2) decreases some of those controlling gluconeogenesis, and (3) has no effect on the enzymes of glycolysis.
...
PMID:Chronic hyperinsulinemia in the fetal rhesus monkey: effects on hepatic enzymes active in lipogenesis and carbohydrate metabolism. 22 50

1. Angiostrongylus cantonensis contains a glucokinase which was isolated by DEAE-cellulose column chromatography. 2. This enzyme has a much higher affinity toward glucose (apparent Km, 0.2 mM) than fructose (apparent Km, 85 mM). Glucose-6-phosphate (10 mM) does not inhibit glucose phosphorylation. 3. Molecular weight obtained by a molecular sieve chromatography (60,000) is also close to the value of mammalian glucokinase. 4. While Vmax value for mannose is one-third smaller than that for glucose, Km for mannose is rather lower than that for glucose. 5. In addition to the cytosol enzyme, a particle bound hexokinase is found in the worm.
...
PMID:Hexokinase of Angiostrongylus cantonensis: presence of a glucokinase. 31 15

Using yeast mutants, it is shown that growth on glucose occurs even in the absence of both hexokinase A and hexokinase B; fructose growth requires at least one of these two enzymes. Expression of hexokinase A and of glucokinase seem to be regulated.
...
PMID:Yeast hexokinase mutants. 32 75

When strains of Saccharomyces cerevisiae carrying a single glucose-phosphorylating enzyme such as hexokinase Pl or hexokinase P2 or glucokinase, are subjected to the selection pressure against the toxic sugar 2-deoxyglucose, the majority of survivors are mutants lacking the respective enzymes. All the 2-deoxyglucose-resistant segregants recovered from backcrosses of these mutants to a wild type strain are glucose-negative and all the sensitive ones are glucose-positive. The hexokinase mutations are located in the same complementation groups as defined by the structural genes of hexokinase P1 and hexokinase P2. No interallelic complementation has been observed either in hexokinase P1 or in hexokinase P2 amongst a total of 4 X 64, and 5 X 60 different combinations of independent mutants at the hxk1 and hxk2 loci respectively. There appears to be neither a common genetic regulator controlling two or more of these glucose-phosphorylating enzymes nor a sugar carrier that can be dispensed with.
...
PMID:Resistance to 2-deoxyglucose in yeast: a direct selection of mutants lacking glucose-phosphorylating enzymes. 34 Sep 26


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---