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)

It is generally recognized that the activities of some of the red cell enzymes decline as the cell ages. However, there is still a controversy regarding the rate at which this aging occurs. In the present study we applied newly developed technology for the specific isolation of maturing reticulocytes/erythrocytes for a more comprehensive study of in vivo aging of red cell enzymes in rabbits. Anemia was induced by repeated phlebotomy, and reticulocyte-rich erythrocytes were labeled with N-hydroxy succinimido-biotin and then transfused into a normal rabbit. These biotinylated cells were isolated at various time points by their affinity for an avidin support, and the enzymatic activity of 19 red cell enzymes was measured. We observed a biphasic pattern of decay for the activity of six age-dependent enzymes--aldolase, glutamate-oxaloacetate transaminase, glucose 6-phosphate dehydrogenase, hexokinase, pyrimidine 5'-nucleotidase, and pyruvate kinase.
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PMID:In vivo aging of red cell enzymes: study of biotinylated red blood cells in rabbits. 231 8

Red cell enzymes of three children with transient erythroblastopenia of childhood were measured and compared with those of age-matched normal children and children with hemolytic anemia. While the activity of "age-dependent" enzyme such as hexokinase, aldolase, glucose-6-phosphate dehydrogenase, glutamic-oxaloacetic transaminase, and pyruvate kinase were greatly increased in the red cells of children with hemolytic anemia, they were not decreased in the red cells of children with erythroblastopenia of childhood. Only the activity of pyrimidine 5'-nucleotidase was consistently low red cells of these children. These findings are inconsistent with the usual concept that red cell enzyme activities decline throughout red cell life span. Rather, they suggest that there may be very rapid loss in the activity of some red cell enzymes during the first few days of red cell life with little further decline in enzyme activity.
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PMID:Age-related red cell enzymes in children with transient erythroblastopenia of childhood and with hemolytic anemia. 298 25

Since pyrimidine nucleotides avidly bind magnesium, we tested the hypothesis that the haemolytic anaemia in hereditary pyrimidine 5'-nucleotidase (P5N) deficiency is due to a state of functional magnesium depletion in the red cell (RBC). In haemolysates from normal subjects, cytidine triphosphate (CTP) inhibited the activity of pyruvate kinase in a competitive manner for magnesium. The CTP Ki was 0.4 mmol/l. CTP inhibited the activity of hexokinase in a competitive manner for ATP (Mg-ATP2-) with a Ki of 4 mmol/l. The inhibitory effect of CTP on both enzymes was overcome by increasing the magnesium content of the test system. Since CTP appeared to inhibit enzymes which required magnesium as a cofactor or Mg-ATP2- as a substrate, we tested the effect of exogenous magnesium on the metabolism of P5N deficient RBC. The autohaemolysis test, the incubated Heinz body assay and the rate of glucose oxidation by the pentose phosphate shunt were abnormal in the intact RBC from a patient with hereditary P5N deficiency. The addition of MgCl2 (6-10 mmol/l) did not improve these abnormal in vitro measures of metabolism in the P5N deficient RBC. This lack of effect of exogenous magnesium may be due to the slow uptake of magnesium by the human RBC.
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PMID:Red cell metabolism in hereditary pyrimidine 5'-nucleotidase deficiency: effect of magnesium. 301 91

Since organotin compounds represent an environmental health hazard, we determined the effect of triethyltin bromide (TTB) on red blood cell (RBC) enzyme activity. TTB produced a concentration-dependent inhibition of hexokinase and pyrimidine 5'-nucleotidase for both adult and cord RBC. D-Glucose, but not ATP or MgCl2, prevented the hexokinase inhibition by TTB. Glucose-6-phosphate dehydrogenase, adenylate kinase, and hypoxanthine-guanine phosphoribosyltransferase were also inhibited by TTB. Cord RBC enzymes were more resistant to the effects of TTB than were adult RBC enzymes. Although TTB is a potent inhibitor of hexokinase, physiologic concentrations of glucose appear to protect the RBC during clinical tin intoxication.
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PMID:Effect of triethyltin on enzyme activity in human adult and cord red cells. 301 93

The present study was conducted to determine the cause of low parasitemia and simultaneous reticulocytosis in canine babesiosis. The parasitemia was significantly decreased in in vitro cultures of Babesia gibsoni by the pretreatment of host canine erythrocytes with lead acetate, which is a specific inhibitor of pyrimidine 5'-nucleotidase subclass I (P5N-I). The serum from dogs chronically infected with B. gibsoni did not decrease the activities of hexokinase, glucose-6-phosphate dehydrogenase or 6-phosphogluconate dehydrogenase in canine reticulocytes, although it was previously reported that this serum had inhibitory effects on both the maturation of reticulocytes and the canine P5N-I and purine-specific 5'-nucleotidase activities. Furthermore, the in vitro multiplication of B. gibsoni was significantly inhibited by pyrimidine nucleotides such as cytidine 5'-monophosphate (5'-CMP), which is preferentially catalyzed by P5N-I and also inhibits the morphological maturation of canine reticulocytes. Purine nucleotides such as inosine 5'-monophosphate (5'-IMP) also had an inhibitory effect on the multiplication of this parasite. These results suggest that nucleotides such as 5'-CMP and 5'-IMP might accumulate in young erythrocytes and/or serum in dogs infected with B. gibsoni as a result of the decreased activity of erythrocyte 5'-nucleotidase, and the accumulation of these nucleotides might inhibit the multiplication of this parasite and simultaneously retard the maturation of reticulocytes. The results obtained from the in vitro examinations in the present study may partially clarify the relationship between low parasitemia and simultaneous reticulocytosis in vivo in canine babesiosis.
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PMID:Inhibitory effect of pyrimidine and purine nucleotides on the multiplication of Babesia gibsoni: possible cause of low parasitemia and simultaneous reticulocytosis in canine babesiosis. 1513 68

Deficiencies in erythrocyte metabolic enzymes are associated with hereditary hemolytic anemia. Here, we report the development of a novel multiplex enzyme assay for six major enzymes, namely glucose-6-phosphate dehydrogenase, pyruvate kinase, pyrimidine 5'-nucleotidase, hexokinase, triosephosphate isomerase, and adenosine deaminase, deficiencies in which are implicated in erythrocyte enzymopathies. To overcome the drawbacks of traditional spectrophotometric enzyme assays, the present assay was based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The products of the six enzymes were directly measured by using ion pairing UPLC-MS/MS, and the precision, linearity, ion suppression, optimal sample amounts, and incubation times were evaluated. Eighty-three normal individuals and 13 patients with suspected enzymopathy were analyzed. The UPLC running time was within 5min. No ion suppression was observed at the retention time for the products or internal standards. We selected an optimal dilution factor and incubation time for each enzyme system. The intra- and inter-assay imprecision values (CVs) were 2.5-12.1% and 2.9-14.3%, respectively. The linearity of each system was good, with R2 values >0.97. Patient samples showed consistently lower enzyme activities than those from normal individuals. The present ion paring UPLC-MS/MS assay enables facile and reproducible multiplex evaluation of the activity of enzymes implicated in enzymopathy-associated hemolytic anemia.
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PMID:Ultra-performance liquid chromatography-tandem mass spectrometry-based multiplex enzyme assay for six enzymes associated with hereditary hemolytic anemia. 2860 Sep 63