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)

Three cell lines established from human gliomas were found to differ in the capacity to phosphorylate the glycolytic enzyme pyruvate kinase in vitro. Phosphorylation in the glioblastoma cell line U-138 was more pronounced than in the glioma cell line Hs 683 and in the glioblastoma cell line A-172. All 3 cell lines showed similar pyruvate kinase isozyme patterns and expressed about 90% K-type and 10% M-type subunits. So, differences in pyruvate kinase phosphorylation could not be explained by differences in the availability of the appropriate substrate, being pyruvate kinase type K. As in gliomas, phosphorylation could specifically and almost completely be inhibited by fructose-1,6-bisphosphate. In order to investigate a potential physiological significance of the phosphorylation of pyruvate kinase, we have characterized these cell lines for several glycolytic parameters. In U-138 cells, the production of lactate appeared to be 2 times higher as compared with A-172 and Hs 683 cells under normal growth conditions and even 4 times higher under low glucose culture regime. The efflux of lactate correlated with the pyruvate kinase phosphorylation pattern in the cell lines. In none of the cell lines could the lactate production be stimulated by glutamine as additional energy source under low glucose culture conditions. The higher glycolytic flux in U-138 cells was not accompanied by higher glycolytic enzyme activities. The isozyme patterns of hexokinase, pyruvate kinase, aldolase, enolase and lactate dehydrogenase in the cell lines were nearly identical and resembled the patterns previously described for solid gliomas. However, the isozyme composition of phosphofructokinase in the cell lines differed from the situation in gliomas. While in gliomas the expression of L-type phosphofructokinase is favored, in the glioma cell lines, we found an increase in the expression of C-type subunits.
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PMID:Phosphorylation of pyruvate kinase and glycolytic metabolism in three human glioma cell lines. 179 9

The 11.5-kDa Zn(2+)-binding protein (ZnBP) was covalently linked to Sepharose. Affinity chromatography with a cytosolic subfraction from liver resulted in purification of a predominant 38-kDa protein. In comparable experiments with brain cytosol a 39-kDa protein was enriched. The ZnBP-protein interactions were zinc-specific. Both proteins were identified as fructose-1,6-bisphosphate aldolase. Experiments with crude cytosol showed zinc-specific interaction of additional enzymes involved in carbohydrate metabolism. From liver cytosol greater than 90% of the following enzymes were specifically retained: aldolase, phosphofructokinase-1, hexokinase/glucokinase, glucose-6-phosphate dehydrogenase, glycerol-3-phosphate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and fructose-1,6-bisphosphatase. Glucose-6-phosphate isomerase, phosphoglycerate kinase, enolase, lactate dehydrogenase, and most of triosephosphate isomerase remained unbound. From L-type pyruvate kinase only the phosphorylated form seems to interact with ZnBP. Using brain cytosol hexokinase, phosphofructokinase-1, and aldolase were completely bound to the affinity column, whereas glucose-6-phosphate isomerase, phosphoglycerate kinase, enolase, lactate dehydrogenase, pyruvate kinase, and most of triose-phosphate isomerase remained unbound. The behavior of glucose-6-phosphate dehydrogenase and glycerol-3-phosphate dehydrogenase from this tissue could not be followed. A possible function of ZnBP in supramolecular organization of carbohydrate metabolism is proposed.
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PMID:Key enzymes of carbohydrate metabolism as targets of the 11.5-kDa Zn(2+)-binding protein (parathymosin). 183 54

It is well known that brain function is critically dependent upon energy metabolism and that the brain has a relatively high metabolic rate. Experiments using intact brain preparations do not provide information about metabolism in the different cell types that constitute brain tissue. Progress in primary culture techniques has facilitated biochemical investigations and analysis of the metabolic pathways prevailing in specific cerebral cell types. We found that, in the presence of pyruvate or succinate as the substrate, oxygen consumption by neurons grown in culture was always higher than that by glial cells. The relatively low values of hexokinase, malate dehydrogenase and glutamate dehydrogenase activities observed in glial cells and, in contrast, the high levels of lactate dehydrogenase and enolase activities may be the result of a less aerobic metabolism prevailing in this type of brain cell, compared to neurons. On the other hand, the predominance of the aerobic, lactate dehydrogenase, isoenzymatic form in neurons can be associated with a more aerobic metabolism in this type of cell. In the case of severe hypoxia, we observed that astrocytes were the most damaged cells. An increased lactate dehydrogenase level with a modification of its isoenzymatic profile and a decreased glutamine synthetase activity under hypoxic conditions indicated severe derangement of important biochemical functions within the astrocytes. By antagonizing some of these changes, almitrine and raubasine (both present in Duxil) seem to exert some protective effect. One may consider that, among the different cell types present in brain tissue, astroglial cells may represent a target particularly sensitive to hypoxia-induced injury.
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PMID:[Neuronal and astrocytic plasticity: metabolic aspects]. 208 81

The alterations in specific activity and/or isozyme pattern of hexokinase, phosphofructokinase, aldolase, enolase, pyruvate kinase and glucose-6-phosphate dehydrogenase were studied in the tissue specimens of 26 patients with lipoblastic tumors and 28 patients with tumors of neurogenic origin. Although the biochemical data demonstrated that the activities of most enzymes studied were elevated in the specimens of the malignant tumors, only the differences in activity of hexokinase, pyruvate kinase and glucose-6-phosphate dehydrogenase measured between benign and malignant neurogenic tumors were significant. In malignant tumors, especially those of neurogenic origin, the isozyme pattern of pyruvate kinase showed a shift towards K-type subunits.
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PMID:Activity of glycolytic enzymes and glucose-6-phosphate dehydrogenase in lipoblastic and neurogenic proliferations. 216 88

The combination of phorbol 12-myristate 13-acetate (PMA) and concanavalin A induces the expression of a new set of glycolytic isozymes in human peripheral lymphocytes. The induced isozyme for each enzyme tested (hexokinase, phosphofructokinase, enolase, pyruvate kinase and lactate dehydrogenase) is usually the muscle form, which is often associated with rapidly dividing tumor cells. Increases in a specific isozyme can account for the 2-5-fold increase in specific activities of the enzyme induced by Con A plus PMA. Increased specific activities and the appearance of the new isozyme forms both occur relatively late, and are probably associated with the G1 or S phase of the cell cycle.
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PMID:Expression of a new set of glycolytic isozymes in activated human peripheral lymphocytes. 216 15

Selected aspects of the metabolism of Plasmodium falciparum are reviewed, but conclusions based on the study of other species of plasmodia are intentionally not included since these may not be applicable. The parasites increase glucose consumption 50-100 fold as compared to uninfected red cells; most of the glucose is metabolized to lactic acid. The parasite contains a complete set of glycolytic enzymes. Some enzymes such a hexokinase, enolase and pyruvate kinase are vastly increased over corresponding levels in uninfected red cells. However, the pathway for synthesizing 2,3-diphosphoglycerate (2,3-DPG) is absent. Parasitized red cells show a decline in the concentration of 2,3-DPG which may function as an inhibitor for certain essential enzyme pathways. Pentose shunt activity is increased in absolute terms, but as a percent of total glucose consumption, there is a decrease during parasite infection of the red cell. The parasite contains a gene for G6PD and can produce a small quantity of parasite-encoded enzyme. It is not clear if the production of this enzyme can be up-regulated in G6PG deficient host red cells. The NADPH normally produced by the pentose shunt can be obtained from other parasite pathways (such as glutamate dehydrogenase). NADPH may subserve additional needs in the infected red cell such as driving diribonucleotide reductase activity--a rate limiting enzyme in DNA synthesis. The role of NADPH in protecting the parasite-red cell system against oxidative stress (via glutathione reduction) remains controversial. Parasitized red cells contain about 10 times more NAD(H) than uninfected red cells, but the NADP(H) content is unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasmodium falciparum carbohydrate metabolism: a connection between host cell and parasite. 225 22

The specific activity of hexokinase, phosphofructokinase, aldolase, enolase, pyruvate kinase and glucose-6-phosphate dehydrogenase was measured in 41 smooth muscle cell tumors: 20 leiomyomas and 21 cases of leiomyosarcoma. Statistical analysis revealed no significant differences in specific activity between normal smooth muscle tissue and the benign and malignant tumors originating from it. Quantification of the isozyme composition of pyruvate kinase showed a significant shift in isozyme pattern towards K-type subunits in leiomyosarcomas as compared to leiomyomas.
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PMID:Activity of glycolytic enzymes and glucose-6-phosphate dehydrogenase in smooth muscle proliferation. 237 98

The glycolytic enzyme 6-phosphofructokinase (EC 2.7.1.11) was studied in adult and fetal type II pneumocytes which had been isolated from rat lung at different days of development. In addition, the activities of the enzymes hexokinase (EC 2.7.1.1), enolase (EC 4.2.1.11) and pyruvate kinase (EC 2.7.1.40) were assayed. The specific activities of the latter enzymes decrease during perinatal development and reach about adult values shortly after birth. In contrast, 6-phosphofructokinase activity increases slightly until 2 days before birth, and drops sharply afterwards. The 6-phosphofructokinase subunit composition was determined in fetal and adult type II cells. The ratio of the three subunits of 6-phosphofructokinase in type II cells isolated on fetal days 19 and 21 (term is at day 22) and in adult type II cells was identical: the three subunits were present in a ratio of 68: 14: 18 for types L, M and C, respectively. In addition, we investigated some regulatory properties of 6-phosphofructokinase from alveolar type II cells. 6-Phosphofructokinase from alveolar type II cells is strongly inhibited by increasing MgATP concentrations. This inhibition is reflected by an increase in the S0.5 for fructose 6-phosphate. Fructose 2,6-bisphosphate stimulates alveolar type II 6-phosphofructokinase. Half-maximal stimulation occurs at 1.6 and 2.0 microM fructose 2,6-bisphosphate for fetal and adult type II cells, respectively. The level of the most potent positive effector of 6-phosphofructokinase, fructose 2,6-bisphosphate, was also determined. The level of the hexose bisphosphate decreases during prenatal development; however, the level in the adult type II cells is considerably lower. The concentration of fructose 2,6-bisphosphate appears to be sufficient to fully activate 6-phosphofructokinase both in fetal and adult type II cells.
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PMID:Phosphofructokinase in alveolar type II cells isolated from fetal and adult rat lung. 252 36

A study on the enzyme activity of glucose metabolism in the lymphocytes of patients with solid malignant tumors is reported. The results have shown a 30% mean increase of the hexokinase (HK) activity in patients with solid malignant tumors as compared to the mean value observed in a group of healthy subjects. A relationship between level of HK increase and stage of tumor was also observed. The other examined enzyme activities, phosphofructokinase (PFK), pyruvate-kinase (PK), phosphoglycerate-kinase (PGK), phosphoglucoisomerase (PGI), glyceraldehyde-phosphate dehydrogenase (GAPD) glucose-6-phosphate dehydrogenase (G-6PD), 6-phosphogluconate dehydrogenase (6-PGD) and enolase did not show significant changes. It is concluded that even though the use of HK as tumor marker cannot be hypothesized at the present time, a significant relation between an increased activity of this enzyme and presence of the tumor is unquestionable. Therefore, this biochemical effect induced away from the neoplastic tissue deserves further study.
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PMID:Solid tumors and enzyme activity in human lymphocytes. 283 4

1. A comparative study was carried out on blood glucose partition and glucose metabolism of penguin erythrocytes and somatic tissues. Pygoscelidae penguins (Pygoscelis antarctica and P. papua) were used in these experiments. 2. Blood glucose partition was established by assaying whole blood and plasma glucose in several individuals of the gentoo and chinstrap penguins. 3. It was found that almost all the whole blood sugar is compartmentalized at the plasma site, the red blood cells being ineffective in regard to glucose metabolism. 4. Levels of hexokinase, phosphoglucose isomerase, phosphofructokinase, fructose bisphosphate aldolase, glyceraldehyde phosphate dehydrogenase, phosphoglycerate kinase, phosphopyruvate hydratase (enolase), pyruvate kinase, alpha-glycerolphosphate dehydrogenase and fructose bisphosphate phosphatase were estimated in the erythrocytes of both gentoo and chinstrap penguins, the same determinations being carried out also on the somatic tissues (leg muscle, breast muscle, heart muscle, liver and brain) of the gentoo.
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PMID:Blood glucose partition and levels of glycolytic enzymes in erythrocytes and somatic tissues of penguins. 292 38


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