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)

Glycosylated hemoglobin (HbA1) is considered to be representative of prior blood-glucose levels and is being used in pregnant and nonpregnant diabetic patients as a possible index of both long and short-term glucose-control. Factors other than blood-glucose concentration have been reported to affect its value. Variant hemoglobin is one of them. HbA1 and blood-glucose levels were measured in pregnant patients at high risk for diabetes for screening for abnormal carbohydrate metabolism. HbA1 was measured by cation exchange column chromatography and glucose was measured by hexokinase reaction. The mean HbA1 in patients with normal blood sugars was 6.17 +/- 0.6 percent. A value of HbA1 of less than 5 percent as measured by cation exchange column chromatography was highly predictive (P less than 0.001) of hemoglobinopathies (S or C). The mean HbA1 of randomly selected matched patients with "normal" Hb was 5.94 +/- 0.72 percent. In patients with thalassemia, HbA1 values as measured by cation exchange column chromatography were elevated despite normal carbohydrate tolerance. While interpreting the results of HbA1 in the management of pregnant diabetics, the above fact should be kept in mind.
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PMID:Glycosylated hemoglobin (HbA1) and hemoglobinopathies in pregnancy. 650 39

A metabolic osmotic model of red blood cells is presented which takes into account the main reaction steps of glycolysis and the passive and active fluxes of ions across the cell membrane. Cellular energy metabolism and osmotic behaviour are linked by the ATP consumption for the active transport of cations as well as by the osmotic action of the glycolytic intermediate 2,3-diphosphoglycerate (2,3-DPG). The model is based on a system of differential equations describing the metabolic reactions and transport processes. Further, two algebraic conditions for the osmotic equilibrium and the electroneutrality of the cell are considered. Using realistic system parameters the model allows the calculation of a great number of dependent variables, among them the cell volume, the concentrations of metabolites and ions and the transmembrane potential. Only stationary states are considered. The parameter dependence of important model variables is characterized by control coefficients. The main results are: (a) The volume of erythrocytes is mainly determined by the permeabilities of the leak fluxes of cations, the content of hemoglobin and the activity of the hexokinase-phosphofructokinase system of glycolysis; (b) Changes of volume affect the glycolytic rate mainly by changing the concentration of ATP which is a regulator of glycolysis; (c) A change in the membrane area may affect the other cell properties only if it is connected with variations of the number of active and leak sites of the membrane.
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PMID:A metabolic osmotic model of human erythrocytes. 652 55

The true level of hexokinase in rabbit erythrocytes was determined by three different methods, including the spectrophotometric glucose-6-phosphate dehydrogenase coupled assay and a new radioisotopic assay. The value found at 37 degrees C (pH 7.2) was 10.23 +/- 1.90 mumol/h per ml red blood cells, which is lower than previously reported values. More than 40 cellular components of the rabbit erythrocytes were tested for their effects on the enzyme. Their intracellular concentrations were also determined. Several of these compounds were found to be competitive inhibitors of the enzyme with respect to Mg X ATP2-. Furthermore, reduced glutathione at a concentration of 1 mM was able to maintain hexokinase in the reduced state with full catalytic activity. The ability of orthophosphate to remove the inhibition of some phosphorylated compounds was examined under conditions similar to cellular (pH 7.2 and 50 microM of orthophosphate) and found to be of no practical interest. In contrast, the binding of ATP4- and 2,3-diphosphoglycerate to the rabbit hemoglobin significantly modifies their intracellular concentrations and the formation of the respective Mg complexes. The pH-dependence of the reaction velocity and of the kinetic properties of the enzyme in different buffer systems were also considered. This information was computerized, and the rate of glucose phosphorylation in the presence of the mentioned compounds was determined. The value obtained, 1.94 +/- 0.02 mumol/h per ml red blood cells, is practically identical to the measured rate of glucose utilization by intact rabbit erythrocytes (1.92 +/- 0.3 mumol/h per ml red blood cells). These results provide further evidence for the central role of hexokinase in the regulation of red blood cell glycolysis.
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PMID:Regulatory properties of rabbit red blood cell hexokinase at conditions close to physiological. 672 85

A method for electrophoretic concentration of differently charged proteins is described. A nonlinear pH gradient is generated by imposing a potential gradient on an electrolyte system composed of (+)H3PO4-valine (pI 6.0)-Servalyte (pH 9-11)-triethylamine(-). Proteins contained in the valine solution accumulate at the interphase formed between the valine solution and the Servalyte solution. This interphase acts as a barrier or liquid membrane to all proteins having isoelectric points in the range 6-9. For proteins having isoelectric points in the range 5-7 valine is replaced by histidine (pI 7.64) and the Servalyte by Pharmalyte, pH 2.5-5.0. Ribonuclease, hexokinase, bovine serum albumin, and hemoglobin were concentrated and recovered from the top of the column using a peristaltic pump. The duration of concentration process was 1-4 h, the length of the run depending on the experiment scale (20 or 100 ml protein solution), the amount of protein, and the isoelectric point of the protein. Proteins were concentrated 9- to 48-fold, depending on the initial volume and concentration of the protein. The recoveries ranged from 79.7 +/- 1.1 for hemoglobin to 93.17 +/- 2.84 for ribonuclease.
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PMID:Electrophoretic concentration of proteins in a nonlinear pH gradient. 673 3

Red cell glycolytic intermediates and enzymes in term infants in the first year of life were correlated with the fetal hemoglobin concentration (%F), intra- and extracellular venous pH, plasma inorganic phosphorus (Pi) and pyruvate kinase (PK) activity. Changes in the non-age-dependent enzymes phosphoglycerate kinase, enolase, and phosphofructokinase correlated most significantly with the postnatal decline in %F (P less than 0.001), not the age of the red cell population, as reflected in PK activity. The age-dependent enzymes, hexokinase and glucose-6-phosphate dehydrogenase, however, correlated well with PK activity (P less than 0.001). The concentration of glucose-6-phosphate did not correlate significantly with the postnatal decline in %F (P greater than 0.05) or PK (P greater than 0.10), but correalted significantly with the plasma Pi concentration (P less than 0.001). "Total triose phosphate" and 2,3-diphosphoglycerate did not correlate with Pi. It appears from these studies that an extracellular factor, Pi alters the pattern of glycolytic intermediates in term infants and that the postnatal changes in phosphoglycerate kinase, enolase, and phosphofructokinase are unique to the "fetal" red cell and reflect passage from fetal to "adult" erythropoiesis.
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PMID:Red cell metabolic alterations in postnatal life in term infants: possible control mechanisms. 725 39

We have developed a kinetic fixed-time approach for the quantitative determination of serum glucose by use of the hexokinase/glucose-6-phosphate dehydrogenase method. To achieve a large measuring range, we have apparently increased the Michaelis constant of glucose-6-phosphate dehydrogenase through addition of the competitive inhibitor ATP. By this means, serum samples with glucose concentrations up to 55.5 mmol/l could be analyzed without pre-dilution. The method has been adapted to the ENI GEMSAEC analyzer and to the LKB 2086 Mark II analyzer. It yielded satisfactory results with regard to precision. A comparison of the kinetic procedure with the manual end-point method showed good agreement. No interferences from hemoglobin, bilirubin, or lipemia have been observed.
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PMID:Kinetic determination of serum glucose by use of the hexokinase/glucose-6-phosphate dehydrogenase method. 735 90

The age changes of 2,3-DPG concentration, 2,3-diphosphoglycerate mutase, hexokinase and pyruvate kinase activities in pigs erythroid cells during the first 10 days after birth have been investigated for study of the mechanism of blood oxygen-transport function regulation at the early stages of postnatal adaptation. It was established, that there are age peculiarities in young, mature and old erythrocytes metabolism in piglets during the transition to postnatal development. It was shown that the rise of 2,3-DPG, the allosteric effector of hemoglobin oxygen affinity level, is due to the increased activities of 2,3-diphosphoglycerate mutase and hexokinase after birth, that is particularly characteristic of the young pigs erythrocytes.
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PMID:[Activity of enzymes of glycolysis in pig erythrocytes in the neonatal period]. 774 43

The oxidative injury to erythrocytes, red blood cell (RBC) rigidity and splenic hemolysis was assayed in 17 chronically hemodialyzed patients before and during recombinant erythropoietin (EPO) treatment. When a stable hematocrit between 30 and 35% had been established for at least 4 months, a statistically significant increase in RBC volume, hemoglobin concentration, hematocrit, reticulocyte count, and several RBC enzymes (2,3-diphosphoglycerate, glucose 6-phosphate dehydrogenase, pyruvate kinase, hexokinase) was noted. This indicated significant RBC rejuvenation under the influence of EPO. However, no significant improvement in the RBC oxidative sensitivity, RBC deformability, splenic RBC volume, slow mixing splenic RBC volume, and the intrasplenic RBC transit time could be disclosed. These data confirm the existence of an extra-erythrocytic factor in uremic plasma, which is partly responsible for a reduced RBC life span in hemodialysis patients despite EPO treatment.
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PMID:Oxidative injury to erythrocytes, cell rigidity and splenic hemolysis in hemodialyzed patients before and during erythropoietin treatment. 824 95

Previous studies have reported erythrocyte macrocytosis in adults and children with Down syndrome (DS), the significance of which remains unclear. We compared hematological parameters of 50 DS children aged 2 to 15 years, divided into three age groups, with those of 68 aged-matched healthy children. Patients with DS had a significantly increased mean corpuscular volume (MCV) and hemoglobin in all groups when compared with the controls. Erythrocyte creatine content, hexokinase (Hk) activity, erythrocyte and serum folates, vitamin B12, haptoglobin, serum iron, and ferritin were tested. All of these parameters were not significantly different from those of the control group. We conclude that macrocytosis may not be an expression of reduced red cell survival but rather of an altered folate remethylation pathway, secondary to enhanced cystathionine beta-synthase (CBS) activity, the gene for which is present on chromosome 21.
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PMID:Hematological studies in children with Down syndrome. 873 44

Muscle ultrastructure and biochemistry in vastus lateralis muscle biopsies and the response to exercise of 8 lowland Tibetans (T) were compared with those of 8 Nepalese lowlanders (N). Blood hemoglobin was lower in T than in N (119 +/- 3 vs. 131 +/- 2 g/l; P < 0.05). Peak O2 consumption per kilogram of body mass was similar [37.9 +/- 2.2 (T) vs. 40.1 +/- 1.36 ml.min-1.kg body mass-1 (N)]. Maximum exercise blood lactate was the same [11.4 (T) +/- 0.5 vs. 11.3 +/- 0.6 mM (N)]. Muscle fiber type distribution was similar [type I, 58.6 +/- 3.4 (N) vs. 57.0 +/- 3.4% (T); type IIa, 24.1 +/- 3.5 vs. 27.1 +/- 1.6%; type IIb, 17.4 +/- 1.4 vs. 15.9 +/- 2.9%]. T had smaller fiber cross-sectional areas [3,413 +/- 677 (T) vs. 3,895 +/- 447 microns 2 (N); P < 0.05] but had similar number of capillaries per muscle fiber [1.35 +/- 0.23 (T) vs. 1.46 +/- 0.08 (N)] and muscle fiber area supplied per capillary [399 +/- 29 (T) vs. 382 +/- 65 mm2 (N)]. Total mitochondrial volume density was much lower in T (3.99 +/- 0.17%) than in N (5.51 +/- 0.19%) (P < 0.025). Mirroring mitochondrial volume density, citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities were lower in T than in N (P < 0.05). The activities of L-lactate dehydrogenase and hexokinase were the same in both groups. T had significantly less muscle fiber lipid droplets than did N, which correlated with the low activity of 3-hydroxyacyl-CoA dehydrogenase (r = 0.57, P = 0.02). In conclusion, lowland-born T have a low mitochondrial volume-to-specific peak O2 consumption ratio, which, based on previous measurements on altitude-born Sherpas (B. Kayser, H. Hoppeler, H. Claassen and P. Cerretelli. J. Appl. Physiol. 70: 1938-1942, 1991), appears to be an inborn feature.
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PMID:Muscle ultrastructure and biochemistry of lowland Tibetans. 882 94


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