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:1.1.1.49 (glucose-6-phosphate dehydrogenase)
7,794 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibition by adenosine 5'-monophosphate (AMP) of the forward reaction of fructose 1,6-bisphosphatase (FBPase) has been studied by means of progress curve analysis. The full time course of the FBPase reaction was followed by coupling the reaction to the enzymes phosphoglucoisomerase and glucose-6-phosphate dehydrogenase. The data were analyzed by using three different methods of regression and these methods are compared. During these progress curve experiments, it was noticed that fructose 1,6-bisphosphate (Fru-P2) was not fully utilized in the presence of AMP. This anomaly could be best explained by proposing the formation of an AMP.Fur-P2 complex that was inactive with FBPase. Besides reducing the level of substrate available to FBPase, AMP caused slope-parabolic, intercept-parabolic noncompetitive inhibition with respect to Fru-P2. A kinetic model for AMP inhibition of the forward reaction of FBPase is presented. Initial rate kinetics were used to study the reverse reaction of FBPase; AMP was a slope-parabolic, intercept-parabolic noncompetitive inhibitor with respect to both fructose 6-phosphate and inorganic phosphate. Initial velocity experiments in which both fructose 6-phosphate and inorganic phosphate were varied were carried out in the absence and presence of AMP. The results of these experiments indicated to which reverse-reaction enzyme forms AMP was binding. The possible physiological significance of the AMP inhibition of FBPase and of the proposed AMP.Fru-P2 complex is discussed.
...
PMID:Studies on the mechanism of adenosine 5'-monophosphate inhibition of bovine liver fructose 1,6-bisphosphatase. 624 53

In order to evaluate properly red cell metabolic data obtained in newborns with congenital hemolytic disorders, the unique metabolic characteristics and normal developmental changes that occur prenatally and postnatally are presented. The age-dependent red cell glycolytic enzymes (hexokinase, aldolase, pyruvate kinase) and glucose-6-phosphate dehydrogenase and most glycolytic intermediates are elevated at birth and at 11 to 12 months of age, consistent with the presence of a young red cell population the entire first year of life. However, certain red cell enzymes are elevated out of proportion to the age of the red cell population [phosphoglucose isomerase. glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase (PGK), and enolase (ENO)] whereas others are decreased [phosphofructokinase (PFK), glutathione peroxidase, carbonic anhydrase, and others]. These metabolic characteristics are felt to be unique and representative of "fetal erythropoiesis." Activities of PGK and ENO decrease the PFK increases toward normal adult values beginning at eight to nine weeks of age. The concentration of glucose-6-phosphate steadily increases after birth and peaks at three to four weeks of age, at a time when PFK activity remains relatively unchanged, suggesting a relative block in glycolysis at the PFK step secondary to an enzyme with both decreased activity and altered kinetic properties (a "fetal" isozyme). Thus, evaluation of red cell enzyme and glycolytic intermediate data obtained in the first year of life should be related to the knowledge that a young red cell population is present and the characteristic unique metabolic red cell alterations described in cord blood persist beyond the immediate neonatal period.
...
PMID:Red cell enzymopathies in the newborn. I. Evaluation of red cell metabolism. 628 May 78

Growth rate, histological course, and polymorphic enzyme pattern (glucose 6-phosphate dehydrogenase, glucose phosphate isomerase, and phosphofructokinase) were studied in eight childhood tumors xenotransplanted serially to nude mice. The growth rate of these tumors (three nephroblastomas, one hypercalcemic renal tumor, three rhabdomyosarcomas, and one malignant histiocytosis) appeared stable for any one particular tumor line. The time interval between two grafts varied from 1 to 3 weeks to 1 to 2 months in correlation with the clinical course of each malignant process. Histological changes were mostly in relation with a progressive dedifferentiation of the grafts. Immunoneutralization of glucose-6-phosphate dehydrogenase and glucose phosphate isomerase made possible the quantification of the stroma reaction in the grafts. A series of ten passages showed the amount of stroma to be constant for a given tumor type but variable from one tumor type to another, except for the malignant histiocytosis which showed an increase in stroma constituent after the sixth passage. One nephroblastoma tumor line showed, during the third passage, a sudden acceleration in the growth rate and complete transformation of the histological and isozymic patterns, which were interpreted as being the result of a murine lymphoma. The fibroblastic form of phosphofructokinase increased in every tumor line, whatever the tumor type. This change may be linked to a progressive dedifferentiation during the passage.
...
PMID:Isozyme pattern in serially xenotransplanted childhood tumors. 631 82

A marked reduction of granulocyte chemotactic function accompanies the storage of granulocyte concentrates. Since chemotaxis is energy dependent, we studied energy metabolism in stored neutrophils. We and others have reported that stored neutrophils have a defect in their energy metabolism. We found that defective adenosine triphosphate maintenance in stored neutrophils was occult in resting cells, but was unmasked by an energy-intensive stimulus, phagocytosis. In studies reported here, we sought to determine if defective adenosine triphosphate maintenance during granulocyte storage was related to altered glycolytic enzyme activity. We studied the activity of glycolytic enzymes in fresh and stored, resting and stimulated (opsonized zymosan) neutrophils. The following enzyme activities showed no major changes during storage, in resting or stimulated neutrophils: hexokinase, phosphofructokinase, aldolase, glucose phosphate isomerase, triose phosphate isomerase, glyceraldehyde phosphate dehydrogenase, phosphoglycerate kinase, phosphoglyceromutase, enolase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, glutathione reductase, and glutathione peroxidase. In contrast, pyruvate kinase activity consistently increased during storage. In 6 units, pyruvate kinase activity increased by 75 percent after 24 hours of storage at room temperature and by 198 percent after 48 hours. The storage-associated increase in pyruvate kinase activity was not inhibited by cycloheximide. Stimulation of neutrophils by phagocytosis of opsonized zymosan also produced striking increases in the pyruvate kinase activity of both fresh and stored cells. Additional studies indicated that the increases in pyruvate kinase activity observed during storage and after phagocytosis were associated with an increase in the availability of pyruvate kinase activity in the supernatant fraction of neutrophil sonicates. Total pyruvate kinase activity in sonicates of neutrophils was unchanged by storage or particle ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Glycolytic enzymes of stored granulocytes. 632 24

Five alleles representing three electromorphs of phosphoglucose isomerase (PGI) have been transferred from natural isolates of E. coli into the genetic background of E. coli K12 and examined for their effect on growth rate in chemostats limited for glucose or fructose. With glucose limitation, all alleles are selectively neutral or nearly neutral within the limit of resolution of the technique, whether the genetic background is nonmutant or whether it contains a deletion of the locus of glucose-6-phosphate dehydrogenase, the enzyme that provides an alternative metabolic pathway for the substrate of PGI. With fructose limitation, one of the naturally occurring alleles has a small but reproducible detrimental effect on growth rate. A kinetic difference in this detrimental allozyme, apparently relating to an inhibition constant, has been observed in some, but not all, lots of substrate, and a similar difference has also been noted in one of the rare electromorphs that could not be transferred into E. coli K12. These results support a model of genetic variation in which the alleles are neutral or nearly neutral in the prevailing environment but have a potential for selection that can be expressed under the appropriate conditions of environment or genetic background. This hypothesis is discussed in the context of allozyme polymorphisms observed in other organisms.
...
PMID:Functional effects of PGI allozymes in Escherichia coli. 635 6

Monocytes purified with cell scatter monitored counterflow centrifugation were cultured in plastic (adherent) and in teflon culture bags (suspension). Sequential changes were monitored during 15 days by measuring intracellular activity of three enzymes of intermediary metabolism: glucose-6-phosphate dehydrogenase (G-6-PDH), phosphohexose isomerase (PHI) and isocitrate dehydrogenase (ICDH), and the two acid hydrolases: acid phosphatase (ACP) and N-acetyl-beta-glucosaminidase (NAG). In teflon grown macrophages a significantly lower G-6-PDH activity was seen after 15 days in comparison to plastic adherent macrophages (P less than 0.0002). For the other enzymes similar values for both culture modalities were found. The significantly, cycloheximide insensitive, higher values for G-6-PDH, PHI and ICDH in 2 h plastic adherent monocytes in comparison with plastic non-adherent monocytes, suggest a relationship between adherent capacity and the level of intermediary metabolism. The overall yield of plastic adherent macrophages after 15 days was 35% in contrast with 89% for the in suspension cultured macrophages. This corroborates the existence of adherent and non-adherent monocytes, both capable of differentiation in vitro. In 14 patients with advanced Hodgkin's disease (HD) and 14 normal controls, monocyte differentiation was studied applying both culture modalities. The enzyme levels, reflecting growth and intermediary metabolism, were similar for both groups. The adherent capacity and yield, both in teflon and in plastic, after 15 days was comparable for both groups. It was concluded that in vitro monocyte differentiation in the presence of autologous serum was qualitatively and quantitatively normal in advanced HD; this is in favour of an intrinsically normal function of monocytes in HD.
...
PMID:Characterization of monocyte maturation in adherent and suspension cultures and its application to study monocyte differentiation in Hodgkin's disease. 636 Apr 44

Mutant cells of mucoid Pseudomonas aeruginosa isolated from cystic fibrosis patients were examined for their ability to synthesize alginic acid in resting cell suspensions. Unlike the wild-type strain which synthesizes alginic acid from glycerol, fructose, mannitol, glucose, gluconate, glutamate, or succinate, mutants lacking specific enzymes of carbohydrate metabolism are uniquely impaired. A phosphoglucose isomerase mutant did not synthesize the polysaccharide from mannitol, nor did a glucose 6-phosphate dehydrogenase mutant synthesize the polysaccharide from mannitol or glucose. Mutants lacking the Entner-Doudoroff pathway dehydrase or aldolase failed to produce alginate from mannitol, glucose, or gluconate, as a 3-phosphoglycerate kinase or glyceraldehyde 3-phosphate dehydrogenase mutant failed to produce from glutamate or succinate. These results demonstrate the primary role of the Entner-Doudoroff pathway enzymes in the synthesis of alginate from glucose, mannitol, or gluconate and the role of glyceraldehyde 3-phosphate dehydrogenase reaction for the synthesis from gluconeogenic precursors such as glutamate. The virtual absence of any activity of phosphomannose isomerase in cell extracts of several independent mucoid bacteria and the impairment of alginate synthesis from mannitol in mutants lacking phosphoglucose isomerase or glucose 6-phosphate dehydrogenase rule out free mannose 6-phosphate as an intermediate in alginate biosynthesis.
...
PMID:Alginic acid synthesis in Pseudomonas aeruginosa mutants defective in carbohydrate metabolism. 640 61

An increase in lactate production, and in activities of phosphohexoisomerase, phosphofructokinase and pyruvate kinase was found in erythrocytes of patients with advanced cancer disease. Phosphofructokinase isolated from patients' erythrocytes showed enhanced affinity for substrate and coenzyme, diminished thermal stability and changed dependence of the activity on pH. Allosteric properties of the enzyme were modified. A decrease in glucose-6-phosphate dehydrogenase activity was observed in hemolysate. The partially purified enzyme showed decreased affinity for glucose-6-phosphate, and markedly reduced stability at 45 degrees C and in the acid and alkaline pH range. Changes in kinetic and molecular properties of the two key enzymes of glucose metabolism may contribute to hemolysis observed in many cancer patients. Incubation in vitro of normal human erythrocytes with blood sera of patients resulted in increasing of phosphofructokinase, and decreasing of glucose-6-phosphate dehydrogenase activity, indicating that an acquired enzymopathy may be present in cancer.
...
PMID:Alterations in erythrocyte enzymes in cancer. 645 Mar 30

Zymogram analysis was used to identify the barley chromosomes that carry the structural genes for particular isozymes. Wheat, barley, and wheat-barley hybrid derivative lines (which contained identified barley chromosomes) were tested by gel electrophoresis for isozymes of particular enzymes. It was found that barley chromosome 4 carries structural genes for acid phosphatase and beta amylase isozymes, barley chromosome 5 carries genes for phosphoglucose isomerase and male dehydrogenase isozymes, and that barley chromosome 2 carries a gene for at least one glucose-6-phosphate dehydrogenase protomer. These results reinforce previous conclusions that barley chromosome 4 shows homoeology with wheat chromosome group 4 and that barley chromosome 5 shows homoeology with wheat chromosome group 1.
...
PMID:Isozymes in wheat-barley hybrid derivative lines. 645 13

The role of metabolic energy in cell maturation-associated loss of membrane functions has been studied using sheep reticulocytes incubated in vitro at 37 degrees C for periods up to 41 hours. ATP either was maintained with glucose, adenosine plus inosine or depleted with 2-deoxyglucose plus arsenate. Two membrane transport systems were studied: Na+-dependent glycine transport and the sodium pump, estimated from the number of specific [3H] ouabain binding sites per cell. Although both transport systems decreased during maturation, the decrease was much less in ATP-depleted cells compared to ATP-replete cells. The phenomenon is relatively specific: not all maturation-associated changes are similarly affected. Thus, the decreases in activity of the cytoplasmic enzymes glucose-6-phosphate dehydrogenase, hexokinase and phosphoglucose isomerase were not prevented by energy depletion. It is concluded that the loss of certain functions during reticulocyte maturation is retarded by metabolic depletion.
...
PMID:The role of metabolic energy in the maturation-associated loss of reticulocyte membrane transport. 650 12


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

---