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)

Factors that influence hemoglobin (Hb)A(Ic) synthesis by intact erythrocytes were studied in vitro. After incubation cells were lysed, and hemoglobins were separated by isoelectric focusing on polyacrylamide slab gels and quantitated by microdensitometry. HbA(Ic) increased with time, glucose concentrations (5-500 mM), and incubation temperature (4 degrees -37 degrees C). Low temperatures allowed prolonged incubations with minimal hemolysis. At 4 degrees C HbA(Ic) increased linearly with time for 6 wk; after incubation at the highest glucose concentration, HbA(Ic) comprised 50% of total hemoglobin. Insulin (1 and 0.1 mU/ml) did not affect HbA(Ic) synthesis in vitro. In addition to glucose, galactose and mannose, but not fructose, served as precursors to HbA(Ic). A good substrate for hexokinase (2-deoxyglucose) and a poor hexokinase substrate (3-O-methylglucose), were better precursors for HbA(Ic) synthesis than glucose, suggesting that enzymatic phosphorylation of glucose is not required for HbA(Ic) synthesis. Autoradiography after erythrocyte incubation with (32)P-phosphate showed incorporation of radioactivity into HbA(Ia1) and A(Ia2), but not HbA(Ib), A(Ic), or A. Acetylated HbA, generated during incubation with acetylsalicylate, migrated anodal to HbA(Ic) and clearly separated from it. Erythrocytes from patients with insulinopenic diabetes mellitus synthesized HbA(Ic) at the same rate as controls when incubated with identical glucose concentrations. Likewise, the rate of HbA(Ic) synthesis by erythrocytes from patients with cystic fibrosis and congenital spherocytosis paralleled controls. When erythrocytes from cord blood and from HbC and sickle cell anemia patients were incubated with elevated concentrations of glucose, fetal Hb, HbC, and sickle Hb decreased, whereas hemoglobins focusing at isoelectric points near those expected for the corresponding glycosylated derivatives appeared in proportionately increased amounts.
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PMID:Synthesis of hemoglobin Aic and related minor hemoglobin by erythrocytes. In vitro study of regulation. 3 12

We studied the interactions of the A- variety of glucose-6-phosphate dehydrogenase (G6PD) deficiency and sickle cell anemia (HbSS) to see if G6PD deficiency influenced laboratory and clinical features of HbSS. A total of 801 male patients over age 2 had G6PD electrophoresis on cellulose acetate membranes. Assays of both G6PD activity and hexokinase activity were then done on all samples that had an electrophoretic pattern other than the normal wild type (GdB). The collection of clinical data used a standardized protocol. Using cluster analyses we classified 10.4% males to be G6PD deficient, while 18.4% had the functionally normal GdA+ enzyme. The prevalence of G6PD deficiency did not change significantly when age was stratified by decade, suggesting little survival advantage or disadvantage of the combination of G6PD deficiency and HbSS. Compared to patients who were not G6PD deficient, there were no significant differences in the hemoglobin concentration, mean corpuscular volume, reticulocyte count, bilirubin, or SGOT level in patients with HbSS who had G6PD deficiency. The incidence of painful episodes, sepsis, or acute anemic episodes was similar in both groups. Our results are consistent with recent studies of smaller numbers of patients that have found little influence of G6PD deficiency upon HbSS. Specifically, we found no evidence that G6PD enhanced the severity of hemolysis or increased the incidence of acute anemic episodes or sepsis in HbSS.
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PMID:Effects of glucose-6-phosphate dehydrogenase deficiency upon sickle cell anemia. 334 44