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)

The enzyme phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), hexokinase (HK), adenylate kinase (AK), fructokinase (FK), mannose-6-phosphate isomerase (MPI), glucose-6-phosphate dehydrogenase (G-6-PDH) and malate dehydrogenase (MDH) were chosen to study the variation between isolates, cercariae and adults, individuals, and sexes of Schistosoma mansoni and S. rodhaini, using horizontal polyacrylamide gel electrophoresis. The method described allows combinations of six of the eight enzymes to be scored in the homogenate from one adult worm. In adult S. mansoni one phenotype of the eight enzymes was observed in all isolates. In addition, the enzyme PGI showed polymorphism in the isolates from Tala, Kenya and Uganda. PGM in the isolates from Tala, Kenya and South Africa showed polymorphism. The cercarial phenotype differs from the adult phenotype in G-6-PDH, where the cercarial enzyme mobility is slower than that in the adult worm. The low amount of intrastrain variation observed in this species is explained by the limited amount of material used to establish the laboratory stocks, whereas the genetic similarity between geographically widely separated stocks does suggest that only limited geographical variation is likely to occur in S. mansoni. It is suggested that the gene controlling the PGI polymorphism is located on the sex chromosomes of S. mansoni. Mobility differences were observed between S. mansoni and S. rodhaini in the enzyme PGI and PGM, and these characteristics might be useful for a quick identification of schistosome cercariae emerging from Biomphalaria sp. in Africa.U
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PMID:Isoenzyme studies on cercariae from monoinfections and adult worms of Schistosoma mansoni (10 isolates) and S. rodhaini (one isolate) by horizontal polyacrylamide gel electrophoresis and staining of eight enzymes. 621

A new and simple enzymatic assay for measuring D-mannose in serum is described. Endogenous glucose is eliminated from serum by use of glucose oxidase (EC 1.1.3.4) and catalase (EC 1.11.1.6). D-Mannose concentration is calculated from the increase in NADH formation after mannosephosphate isomerase (EC 5.3.1.8) is added. This increase is a result of coupling the following series of enzymes: hexokinase (EC 2.7.1.1), glucosephosphate isomerase (EC 5.3.1.9), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, NAD+-dependent). The study included subjects who were healthy volunteers and patients with suspected or proven fungal infections.
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PMID:Enzymatic determination of D-mannose in serum. 669 39

Uptake and metabolism of mannose were studied in astroglia-rich primary cultures derived from neonatal rat brains. A saturable component of mannose uptake was found with half-maximal uptake at 6.7 +/- 1.0 mM mannose. In addition, a non-saturable component dominated the uptake at high concentrations of mannose. Glucose, cytochalasin B, or phloretin in the incubation buffer inhibited the carrier-mediated uptake of mannose. Within the astroglial cells mannose is phosphorylated to mannose-6-phosphate. In cell homogenates, the KM value of mannose-phosphorylating activity was determined to be 24 +/- 7 microM. The Vmax value of this activity is only 40% that of glucose-phosphorylating activity. Mannose-6-phosphate was converted to fructose-6-phosphate by mannose-6-phosphate isomerase. The specific activity of this enzyme in homogenates of astroglial cultures was higher than that of hexokinase. Two products of mannose utilization in astroglial cells are glycogen and lactate. The amounts of each of these products increased with increasing concentrations of mannose. In contrast to the generation of lactate, that of glycogen from mannose was enhanced in the presence of insulin. In conclusion, we suggest that mannose is taken up into the cells of astroglia-rich primary cultures by the glial glucose transporter and is metabolized to fructose-6-phosphate within the astroglial cells.
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PMID:Utilization of mannose by astroglial cells. 813 58

Previous work has indicated that sugar sensing may be important in the regulation of fructan biosynthesis in grasses. We used primary leaves of barley (Hordeum vulgare cv Baraka) to study the mechanisms involved. Excised leaf blades were supplied in the dark with various carbohydrates. Fructan pool sizes and two key enzymes of fructan biosynthesis, sucrose (Suc):Suc-1-fructosyltransferase (1-SST; EC 2. 4.1.99) and Suc:fructan-6-fructosyltransferase (6-SFT; EC 2.4.1.10) were analyzed. Upon supply of Suc, fructan pool sizes increased markedly. Within 24 h, 1-SST activity was stimulated by a factor of three and 6-SFT-activity by a factor of more than 20, compared with control leaves supplemented with mannitol (Mit). At the same time, the level of mRNA encoding 6-SFT increased conspicuously. These effects were increased in the presence of the invertase inhibitor 2, 5-dideoxy-2,5-imino-D-mannitol. Compared with equimolar solutions of Suc, glucose (Glu) and fructose stimulated 6-SFT activity to a lesser extent. Remarkably, trehalose (Tre; Glc-alpha-1 and 1-alpha-Glc) had stimulatory effects on 6-SFT activity and, to a somewhat lesser extent, on 6-SFT mRNA, even in the presence of validoxylamine A, a potent trehalase inhibitor. Tre by itself, however, in the presence or absence of validoxylamine A, did not stimulate fructan accumulation. Monosaccharides phosphorylated by hexokinase but not or weakly metabolized, such as mannose (Man) or 2-deoxy-Glc, had no stimulatory effects on fructan synthesis. When fructose or Man were supplied together with Tre, fructan and starch biosynthesis were strongly stimulated. Concomitantly, phospho-Man isomerase (EC 5.3.1.8) activity was detected. These results indicate that the regulation of fructan synthesis in barley leaves occurs independently of hexokinase and is probably based on the sensing of Suc, and also that the structurally related disaccharide Tre can replace Suc as a regulatory compound.
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PMID:Disaccharide-mediated regulation of sucrose:fructan-6-fructosyltransferase, a key enzyme of fructan synthesis in barley leaves. 1080 43

Goldman, Manuel (The University of Michigan, Ann Arbor), and Harold J. Blumenthal. Pathways of glucose catabolism in Bacillus cereus. J. Bacteriol. 87:377-386. 1964.-Estimates by a radiorespirometric method of the pathways of glucose catabolism of resting-cell suspensions of Bacillus cereus strain terminalis indicate that the Embden-Meyerhof pathway predominates at every stage of development, including the sporogenic and germinative phases. At the filamentous, granular, forespore, and transitional stages, 98% of the glucose was catabolized by the Embden-Meyerhof pathway, and the remainder by the hexose monophosphate oxidative pathway. Estimates of the pathways in resting spore-suspensions arrested at defined stages of development indicate that 20% of the glucose was catabolized through the hexose monophosphate pathway in germinated spores, and 10% in the swollen and elongated stages of postgermination. In cells which had completed the first cell division, the figure fell to about 2%, a level similar to that found for vegetative cells at later stages of development. The key Embden-Meyerhof enzymes, hexokinase, phosphohexoisomerase, phosphofructokinase, and aldolase, as well as several other enzymes, were present at all stages of germination and postgerminative development, supporting the radioisotopic data obtained with whole cells. As indicated by the release of C(14)O(2) from glucose-6-C(14), terminal respiration of resting-cell suspensions operates maximally in vegetative cells at the granular, fore-spore, and transitional stages. There was marked inhibition of terminal respiration during the development of spores into vegetative cells. Only slight activity occurred in the earliest vegetative stages, and maximal operation developed after about ten cell divisions. Fumarase was absent in spores until sometime late in the elongation stage. At this point, a weak but definite activity appeared which increased during later stages of development so that, by the end of about the sixth cell division, fumarase had a specific activity about 80 times that observed at elongation.
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PMID:PATHWAYS OF GLUCOSE CATABOLISM IN BACILLUS CEREUS. 1415 Oct 60

Meloche, H. P., Jr. (Northern Regional Research Laboratory, Peoria, Ill.). Enzymatic utilization of glucose by a basidiomycete. J. Bacteriol. 83:766-774. 1962.-Cell-free extracts of acetone-dried Lactarius torminosus NRRL 2900 were prepared. These extracts contained hexokinase. They also contained triphosphopyridine nucleotide (TPN)-specific glucose-6-phosphate dehydrogenase and catalyzed the reduction of TPN in the presence of d-fructose-6-phosphate, 6-phospho-d-gluconic acid (6PG), and d-ribose-5-phosphate (R5P). Aged preparations oxidized d-glucose-6-phosphate (G6P) to 6PG, whereas fresh preparations oxidized G6P to a pentose with the uptake of 1 mumole of O(2) and the evolution of 1 mumole of CO(2) per mumole of G6P. Evidence for the action of transketolase in the metabolism of R5P by cell-free extracts was obtained.Cell-free preparations lacked hexosediphosphate enzymes. Triosephosphate isomerase and F6P kinase could not be demonstrated; however, aldolase activity was present. Evidence is presented for the conversion of d-glyceraldehyde-3-phosphate to pyruvate. In addition, phosphohexoisomerase was demonstrated. It appears that a hexosemonophosphate pathway operates in L. torminosus extracts and may be the major mechanism of glucose dissimilation in this organism.
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PMID:Enzymatic utilization of glucose by a basidiomycete. 1447 42

This study aims at assessing the conversion of exogenous D-[1-13C]fructose, D-[2-13C]fructose or D-[6-13C]-fructose (10 mM) to 13C-enriched and either hydrogenated or deuterated D-glucose, L-lactate and L-alanine released by rat liver cells prepared from Goto-Kakizaki rats and incubated for 120 min in the presence of unlabelled D-glucose (also 10 mM) and D2O. The results of this study are relevant to the relative contribution of fructokinase and hexokinase isoenzyme to the phosphorylation of D-fructose, the capacity of D-glucose to confer to glucokinase positive cooperativity towards D-fructose, the circulation of D-fructose 6-phosphate in the pentose phosphate pathway, the regulation of the cytosolic NADD/NADH ratio, the respective fate of D-fructose-derived D-glyceraldehyde and dihydroxyacetone phosphate, the deuteration of fructose-derived glycolytic intermediates at the phosphoglucoisomerase, phosphomannoisomerase, enolase, pyruvate kinase and glutamate-alanine transaminase levels, and the unequal generation of L-[1-13C]lactate by cells exposed to D-[1-13C]fructose or D-[6-13C]fructose versus D-[2-13C]-fructose.
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PMID:Metabolism of 13C-enriched D-fructose in hepatocytes from Goto-Kakizaki rats. 1506 73

MPI encodes phosphomannose isomerase, which interconverts fructose 6-phosphate and mannose 6-phosphate (Man-6-P), used for glycoconjugate biosynthesis. MPI mutations in humans impair protein glycosylation causing congenital disorder of glycosylation Ib (CDG-Ib), but oral mannose supplements normalize glycosylation. To establish a mannose-responsive mouse model for CDG-Ib, we ablated Mpi and provided dams with mannose to rescue the anticipated defective glycosylation. Surprisingly, although glycosylation was normal, Mpi(-/-) embryos died around E11.5. Mannose supplementation even hastened their death, suggesting that man-nose was toxic. Mpi(-/-) embryos showed growth retardation and placental hyperplasia. More than 90% of Mpi(-/-) embryos failed to form yolk sac vasculature, and 35% failed chorioallantoic fusion. We generated primary embryonic fibroblasts to investigate the mechanisms leading to embryonic lethality and found that mannose caused a concentration- and time-dependent accumulation of Man 6-P in Mpi(-/-) fibroblasts. In parallel, ATP decreased by more than 70% after 24 h compared with Mpi(+/+) controls. In cell lysates, Man-6-P inhibited hexokinase (70%), phosphoglucose isomerase (65%), and glucose-6-phosphate dehydrogenase (85%), but not phosphofructokinase. Incubating intact Mpi(-/-) fibroblasts with 2-[(3)H]deoxyglucose confirmed mannose-dependent hexokinase inhibition. Our results in vitro suggest that mannose toxicity in Mpi(-/-) embryos is caused by Man-6-P accumulation, which inhibits glucose metabolism and depletes intracellular ATP. This was confirmed in E10.5 Mpi(-/-) embryos where Man-6-P increased more than 10 times, and ATP decreased by 50% compared with Mpi(+/+) littermates. Because Mpi ablation is embryonic lethal, a murine CDG-Ib model will require hypomorphic Mpi alleles.
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PMID:Ablation of mouse phosphomannose isomerase (Mpi) causes mannose 6-phosphate accumulation, toxicity, and embryonic lethality. 1633 37

Macroconidia of Fusarium solani f. phascoli have no detectable capacity to respire glucose anaerobically; germinated spores and mycelium, on the other hand, ferment glucose, although slowly.Extracts of ungerminated spores contain hexokinase, phosphohexoisomerase, phosphofructokinase, aldolase, triose phosphate dehydrogenase, triose phosphate isomerase, phosphoglyceric kinase, enolase, phosphoglyceric mutase, pyruvate kinase, and pyruvate decarboxylase. It follows, therefore, that the appearance of fermentative capacity during spore germination cannot be ascribed to the de novo synthesis of any of these enzymes.During germination and mycelial development the specific activity of all of the enzymes named except phosphohexoisomerase and aldolase increases 2- to 8-fold. Specific activity of all of the enzymes is substantially higher than the fermentative capacity of intact cells, i.e., none is limiting to anaerobic respiration.The enzymatic assay data are consistent with a conclusion reached earlier on the basis of studies of aerobic glucose metabolism, that the process of germination involves an acceleration of pre-existing metabolic systems rather than an appearance of new pathways.
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PMID:Spore Germination and Carbon Metabolism in Fusarium solani V. Changes in Anaerobic Metabolism and Related Enzyme Activities during Development. 1665 24

Enzyme activity changes in reagent and neoplastic glia are examined. In the case of reagent glia, considerably increased ADPase, ATPase and AMPase values have been observed in experimental elective parenchymal necrosis in the rat, in hypertrophic astrocytes from recent plaques in multiple necrosis, in demyelinisation associated with cyanide encephalopathy, and in reagent astrocytes surrounding tumours and arteriosclerosis sites. Depressed ATPase values have been observed in experimental oedema, as compared with increased TPPase in human oedema. BuChE and ChE activity disappears in both oligodendro- and astroglia near old cerebral infarct sites, whereas there is marked BuChE activity peripherally to multiple sclerosis plaques and in areas of phenylpyruvic oligophrenia demyelinisation. In neoplastic glia, ADPase is clearly evident in malignant gliomas, ATPase is related to the extent of the cell body, AMPase is positive in medulloblastoma cell cytoplasm and beta-glucuronidase increases in anaplasia. Above-normal ChE activity has been observed in astrocyte tumors, while BuChE is greater than that of AChE. Phosphorylase reaction is intense in astrocytoma and in glioblastoma giant cells. Phosphoglucomutase values are below-normal in tumours, except in the case of ependymoma, while both phosphohexoisomerase and hexokinase display increased activity in atypical forms.
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PMID:[Histochemical demonstration of glial enzyme activity. II. Reagent and neoplastic glia]. 1734 Aug 8


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