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)

Clinical and hematological studies were performed on ten homozygous and seven heterozytous individuals with pyruvate kinase deficiency, aged between 2 and 71 years. Five of the homozygotes were splenectomized. With the exception of a decreased enzyme activity between 41 and 55 per cent and minor changes in their red cell metabolism the heterozygotes showed no abnormal results. In the homozygotes the following results could be demonstrated: 1. Pyruvate kinase activity was decreased to 11 to 35 per cent of normal enzyme activity. 2. There is no relation between the severity of hemolysis and the degree of the enzyme defect. 3. The reticulocyte counts correlated inversely with the hemoglobin concentrations. 4. There is a close correlation between the activities of hexokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase and glutamate oxalacetate transaminase on the one side and reticulocyte counts on the other. 5. Adenosine triphosphate or adenosine reduced the increased autohemolysis in all cases. 6. Following splenectomy, anemia was less pronounced than before. Splenectomized patients did not need further transfusions, though hemolysis persisted.
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PMID:[Pyruvate kinase deficiency. I. Clinical and hematological observations (author's transl)]. 12 93

15 cases of congenital haemolytic anaemia have thus far been attributed to hexokinase (HK) deficiency in erythrocytes. We report some clinical, biochemical and genetic findings from 5 members of a Finnish family with this deficiency. The proband, a 1-year-old girl, was the only patient with anaemia. All subjects had either mild or marked reticulocytosis. Red cell ATP levels were at the lower range of normal in all subjects and 2,3-DPG was abnormally low in one. The activities of red cell enzymes, other than HK, were within or above the normal range, respectively. The Km-values for glucose and fructose were elevated (ATP normal) in the subjects with HK deficiency. We speculate that the family represents heterozygosity of a mutant allele and that there is phenotypic variation associated with the HK mutant. The locus might be subject to mutations which lead to a variety of HK variants and to a spectrum of diseases. This point of view is in accordance with the overwhelming variation of reaction kinetics and metabolic effects of this and other reported cases.
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PMID:Hexokinase deficiency in erythrocytes: a new variant in 5 members of a Finnish family. 45 52

The isoenzyme pattern of hexokinase in rabbit red cells (erythrocytes, fetal erythrocytes and reticulocytes) were determined by means of agarose gel and disc electrophoresis. One duplicated hexokinase (4a and 4b according to the IUPAC-nomenclature) was detected in rabbit erythrocytes as also described for human erythrocytes. Besides the isoenzymes 4a and 4b reticulocytes also contain hexokinase 2 and 3 like rabbit and rat liver. The high KM glucose phosphorylating enzyme, hexokinase 1 could be demonstrated only under specific conditions in the reticulocytes during the initial stage of the anemia. After the fractionation of reticulocyte homogenates the total hexokinase activity was recovered in the mitochondria and cytosol to nearly equal amounts as revealed by the distribution of markers. Hexokinase 2 and 3 were detectable in reticulocytes and in isolated mitochondria only after the addition of certain dissociating agents. In contrast to the tightly bound mitochondrial hexokinases 2 and 3 the type 4a and 4b are more loosely bound and exhibit a bilocal distribution between mitochondria and cytosol of reticulocytes.
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PMID:Electrophoretic characterization and subcellular distribution of hexokinase isoenzymes in red blood cells of rabbits. 53 87

The activity of hexokinase, glucose-6-phosphoric dehydrogenase, lactic dehydrogenase, succinic dehydrogenase, acid and alkaline phosphatases was determined in the rat kidney tissue with phenylhydrazine anemia and posttransfusion polycytemia. The blood supply of the cortical and medullary layers of the kidneys was studied at the same time. The purpose of this work was to ascertain possible connections between the changes in the activity of the enzymes under study with the renal erythropoietin producing function of the kidneys. The blood supply of the kidneys of rats with phenylhydrazine anemia was sharply decreased, but it was markedly elevated in case of posttransfusion polycytemia. There were no significant changes in the activity of the mentioned enzymes. These data suggest that the activity of the kidney enzymes is not a controlling factor in the renal erythropoietin production.
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PMID:[Activity of kidney tissue enzymes in phenylhydrazine anemia and post-transfusion polycythemia]. 89 Jan 28

1. The relationship between red cell aging and enzyme activities was studied in rabbit, guinea-pig, hamster, rats (F344/N and SD), and mice (BALB/c and DBA/2). 2. The activities of six enzymes: glucose-6-phosphate dehydrogenase (G-6-PD), 6-phosphogluconate dehydrogenase (6-PGD), hexokinase (Hx), glutamate oxaloacetate transminase (GOT), lactate dehydrogenase (LDH) and acetylcholinesterase (AChE), were measured in the red cells of different ages which were obtained either by centrifugation or experimental anaemia. 3. Hx, AChE and GOT activities were much higher in younger red cells than in older cells, hence the activities of these enzymes may be used as an indicator of age of the cells.
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PMID:The relationship between red cell aging and enzyme activities in experimental animals. 176 9

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

Normal fetal ranges for red cell glycolytic intermediates at 18-24 weeks gestation, which are useful as reference values for the prenatal diagnosis of erythroenzymopathies, were established for the first time. Characteristic increases in glucose-6-phosphate (G6P), fructose-6-phosphate (F6P) and particularly fructose-1,6-diphosphate (FDP) suggest that there is no metabolic block at the phosphofructokinase (PFK) step of glycolysis as previously suggested by others for premature infants on the first day of life. Neither reticulocytosis nor anaemia consistently led to further increases in the early metabolites as occurs in adults. However, very large increases in G6P, F6P and particularly FDP may occur independently of anaemia and reticulocytosis. This suggests that activation of hexokinase (HK) and/or PFK can take place as in adults but the stimulus is probably different to adults. The 2,3-DPG in normal fetuses is higher than in adults and increases still further in anaemic fetuses with or without transfusion of adult blood. The pattern of intermediates found in the fetus suggests that the controlling mechanism for the increased 2,3-DPG may be an in vivo relative preponderance of PFK activity over that of pyruvate kinase (PK) rather than regulation of HK as proposed for adult subjects with anaemia or high altitude hypoxia.
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PMID:Red cell glycolytic intermediates in normal, anaemic and transfused human fetuses. 260 26

The hematological parameters of young (2-month-old) and old (2-year-old) mice were compared. No differences could be detected with the exception of an increased percentage of reticulocytes in the old animals suggesting that anemia in senescent mice does not occur. Red blood cell mean half-life in old mice was 8 +/- 0.8 days compared to 12 +/- 1 days in young mice. This reduced survival of red blood cell is not due to a different rate of cell phagocytosis in the reticulohistiocytic system of young and old animals since erythrocytes from young mice have the same mean half-life when injected both in young and old animals and vice versa. Thus, the old mice have a reduced red cell life-span but the same hematocrit of the young, suggesting that old animals possess a chronologically younger population of erythrocytes than do young animals. This has been confirmed by measuring the specific activities of some red blood cell age-dependent enzymes (hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase) that were found to be higher in the older animals, and by the separation of erythrocytes into different density (age) groups by Percoll/albumin density gradient centrifugation. However, the erythrocytes osmotic fragility, and the cellular contents of adenine and pyridine nucleotides, as well as the content of 2,3-diphosphoglycerate and reduced glutathione, show that circulating erythrocytes in old animals constitute an heterogeneous cell population whose properties cannot be explained on the basis of a chronologically younger erythrocyte population. Furthermore, evaluation of cell components in hemopoietic tissues have shown an increased porportion of erythroid precursor cells in old animals confirming that old mice compensate for reduced red cell survival with an increased erythropoiesis.
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PMID:Effect of age on some properties of mice erythrocytes. 334 96

Erythrocyte glycolysis has been studied in the anaemia associated with protein-energy malnutrition (PEM) in Kivu. Several results were compatible with a lowering of the mean age of the erythrocyte population, notably raised levels of glucose-6-phosphate, hexokinase, Na+-K+- adenosinetriphosphatases and potassium, and low sodium concentration. Non-significant differences were observed for glucose utilization, lactate formation, and for concentrations of fructose-6-phosphate, fructose-1,6-diphosphate, adenosine diphosphate and pyruvate kinase; there was no gross disturbance of cation transport. The level of adenosine triphosphate was slightly decreased and that of 2,3-bisphosphoglycerate was not elevated, in spite of anaemia. The latter could not be explained by an instability of this metabolite. It is concluded that slight erythrocyte glycolytic abnormalities may occur in the anaemia of Kivu PEM, but that they are not the main cause of the haemolysis observed in this syndrome.
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PMID:Erythrocyte glycolysis in protein-energy malnutrition. 629 Jan 7

Rabbit red blood cells contain hexokinase type I whereas in the reticulocyte two distinct molecular forms (HK Ia and Ib) are present. One (HK Ia) corresponds to hexokinase type I from other tissues, while the other differs from any previously reported isozyme. Rabbit bone marrow cells contain hexokinase type I and II. However, when the erythroid precursor cells become predominant over the non-erythroid cells (during phenylhydrazine anemia) a great increase of HK Ia can be observed concomitant with the appearance of HK Ib. Fractionation of the bone marrow cells on density gradients provides evidence that basophil erythroblasts and proerythroblasts contain only HK Ia while HK Ib appears at the reticulocyte stage. Maturation and ageing of circulating reticulocytes are associated with the decrease of hexokinase activity. Since the decay rate of HK Ib is about three times higher than the decay rate of HK Ia, the mature erythrocytes do not contain appreciable amounts of HK Ib. Furthermore, in vitro, HK Ia and Ib possess similar stabilities so that a cellular mechanism must be responsible of their in vivo different decay rates. This mechanism, as reported in this paper, is ATP-dependent, could be found in the soluble fraction, and is active only at the reticulocyte stage. These properties are similar to those of the ATP-dependent proteolytic system. Pure ubiquitin, an essential polypeptide of the ATP-dependent proteolytic system, is also able to catalyze the decay of hexokinase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rabbit red blood cell hexokinase. Mechanism of decay during cell life-span. 667 10


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