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)

Erythrocyte enzyme activities in patients with reticulocytosis or transient erythroblastopenia show that loss of age-dependent enzyme activity is not a simple exponential process occurring throughout the life-span of the cell. In vivo studies of reticulocyte maturation in rabbits indicate that there are multiple mechanisms of enzyme decay, and that proteolysis continues after the maturation of (morphologically recognisable) reticulocytes into young erythrocytes. Most reticulocyte hexokinase is degraded by lysosomal proteolysis, apparently triggered by an initial attack by lipoxygenase.
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PMID:The loss of enzyme activity from erythroid cells during maturation. 180 84

The rate at which the activities of red cell enzymes decay during maturation of the reticulocyte and ageing of the erythrocyte is poorly understood. It has recently been suggested that loss of enzyme activity may be rapid during reticulocyte maturation and occur slowly thereafter. We have now devised a rabbit model in which reticulocytosis is combined with transfusional polycythaemia. This makes it possible to follow the enzymatic activity of a cohort of reticulocytes without the interfering effect of newly formed cells. In this model the reticulocyte count of the experimental animals falls from about 60% to subnormal levels within 4 d. Red cell hexokinase activity declined rapidly with more than half of the activity being lost within 7 d, little change occurring thereafter. Glucose-6-phosphate dehydrogenase activity declined more gradually, but also followed a biphasic course. The fall of pyrimidine 5' nucleotidase activity was the slowest of the three age-dependent enzymes studied. This is consistent with our observations in children with transient erythroblastopenia of childhood, in which this enzyme, alone of the age-dependent enzymes, was found to be decreased in a senescent red cell population. In contrast to the three age-dependent enzymes studied, the activity of lactate dehydrogenase remained unchanged during the course of the experiment. These studies provide direct verification of the suggestion that the decline of red cell enzyme activities may be biphasic. They show, moreover, that enzyme decay is not only rapid in reticulocytes, but also in young erythrocytes.
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PMID:The in vivo ageing of red cell enzymes: direct evidence of biphasic decay from polycythaemic rabbits with reticulocytosis. 283 67

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