Erythrocyte Glucose-6-phosphate Dehydrogenase Research Articles

The effects of chemical and radioactive properties of Tl-201 on human erythrocyte glucose 6-phosphate dehydrogenase activity

The inhibitory effects of thallium-201 ((201)Tl) solution on human erythrocyte glucose 6-phosphate dehydrogenase (G6PD) activity were investigated. For this purpose, erythrocyte G6PD was initially purified 835-fold at a yield of 41.7% using 2',5'-Adenosine diphosphate sepharose 4B affinity gel chromatography. The purification was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which showed a single band for the final enzyme preparation. The in vitro and in vivo effects of the (201)Tl solution including Tl(+), Fe(+3) and Cu(+2) metals and the in vitro effects of the radiation effect of the (201)Tl solution and non-radioactive Tl(+), Fe(+3) and Cu(+2) metals on human erythrocyte G6PD enzyme were studied. Enzyme activity was determined with the Beutler method at 340 nm using a spectrophotometer. All purification procedures were carried out at +4 degrees C. (201)Tl solution and radiation exposure had inhibitory effects on the enzyme activity. IC(50) value of (201)Tl solution was 36.86 microl ([Tl(+)]: 0.0036 microM, [Cu(+2)]: 0.0116 microM, [Fe(+3)]: 0.0132 microM), of human erythrocytes G6PD. Seven human patients were also used for in vivo studies of (201)Tl solution. Furthermore, non-radioactive Tl(+), Fe(+3) and Cu(+2) were found not to have influenced the enzyme in vitro. Human erythrocyte G6PD activity was inhibited by exposure for up to 10 minutes to 0.057 mCi/kg (201)Tl solution. It was detected in in vitro and in vivo studies that the human erythrocyte G6PD enzyme is inhibited due to the radiation effect of (201)Tl solution.

Comparisons of different methods of anesthesia and analgesia on the levels of glycometabolism rate-limiting enzymes in erythrocytes and plasma glucose and stress hormones in patients undergoing esophagus surgery

Objective To compare the effects of different methods of anesthesia and analgesia on the activities of phosphofructokinase(PFK), glucose-6-phosphate dehydrogenase(G-6PD) and aldose reductase(AR) in erythrocytes and levels of plasma glucose and stress hormones in patients undergoing esophagus surgery. Methods Sixty-two patients scheduled for esophagus surgery were randomly divided into three groups: group I( n = 20) receiving only general anesthesia(GA) followed by intravenous patient controlled analgesia(PCA) with fentanyl 15μg/kg. The other two groups receiving both general anesthesia combined with thoracic epidural anesthesia (GEA) and either intravenous PCA with fentanyl 15μg/kg (group II, n = 21) or thoracic epidural analgesia(TEA) with 0.125% ropivacaine and 0.0002% fentanyl mixture(group III, n = 21) after the operation. Venous blood samples were collected for measurements of PFK, G-6PD and AR activities in erythrocytes and plasma glucose, cortisol, epinephrine and norepinephrine before induction (T 1), 60 min following the incision (T 2), 60 min(T 3) after operation, on the 1st(T 4) and 2nd postoperative day(T 5). Results The activities of PFK decreased( P < 0.01 or P = 0.004) and the activities of G-6PD and AR increased( P < 0. 01) in groups I and II on T 4 compared with those on T 1. Between the two groups, the activities of these enzymes in group II changed less than those of group I( P < 0.01 or P < 0.05). These enzymes activities changed slightly in group III on T 4( P > 0.05). There were significant differences between group III and the other two groups( P < 0.01 or P < 0.05). The levels of plasma glucose increased significantly on T 2( P < 0.01), reached peak values on T 4( P < 0.01) and fell on T 5 in the three groups. Compared to those of groups I and II, the values of plasma glucose in group III were lower on T 4 and T 5( P < 0.05 or P < 0.01). The cortisol concentration in each group increased significantly at T 2( P < 0.01 or P < 0.05), and remained elevated on T 5( P < 0.01 or P < 0.05), while on T 2 and T 3 the cortisol levels of group'were higher than that of groups II and III ( P < 0.05). The levels of group III were lower than those of the other groups on T 4 and T 5( P < 0.01 or P < 0.05). The levels of epinephrine and norepinephrine were also significantly higher in group I than those of the other two groups on T 2( P < 0.01 or P < 0.05), and their levels in group I and II were higher than that of group III on T 4. The patients of the three groups obtained satisfactory pain relief, with all Vidual Analogue Scale(VAS) scores less than 3. VAS scores of group I were much greater 4h after operation. Group III VAS scores were the lowest 24h after operation. However, the number of times patients pressed the bolus switch was higher in group II ( P < 0.01). Conclusion Compared with GA and intravenous PCA, general anesthesia combined with thoracic epidural anesthesia and analgesia obtain better pain relief and could markedly alleviate the stress response and improve these erythrocyte glucose metabolism changes after esophagus surgery.

Glucose‐6‐phosphate dehydrogenase (G6PD) deficiency and senile cataract in a sardinian population, Italy

Abstract Purpose There is still no general agreement on the role of G6PD deficiency in the pathogenesis of cataract. Although G6PD deficiency has been correlated with cataract in some studies, other reports have showed no correlation. The purpose of this study was to determine the prevalence of G6PD deficiency in male patients of Sardinian origin with senile cataract and to compare it with the prevalence rate of G6PD deficiency in the general population of the same area. Methods Erythrocyte G6PD activity was determined using a quantitative assay in 1628 male patients with cataract. The control group consisted of 1646 apparently healthy male patients from the same area described in a former study. Student’s t test was used to determine differences between groups. Results G6PD deficiency was found in 134 (8.2%) patients with cataract and in 120 (7%) control subjects. Differences between cases and controls were not statistically significant (P=0.78). Conclusion The results of this large study suggest that male patients with G6PD deficiency in the Sardinian population do not have a higher risk of developing presenile cataract.

α-Tocopherol supplementation restores the reduction of erythrocyte glucose-6-phosphate dehydrogenase activity induced by forced training

Background Erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity is closely related to free radical production. α-Tocopherol (alpha-T) is implicated with the reduction of lipid peroxidation. Aim To investigate the effect of training and alpha-T supplementation on the erythrocyte G6PD activity. Methods Blood was obtained from 10 basketball players pre-game (group A), post-game (group B) and after 30 days on alpha-T ( dl-alpha-tocopheryl-acetate, 200 mg 24 h −1 orally) supplementation pre- (group C) and post-training (group D). alpha-T and catecholamines were evaluated with HPLC methods and creatine kinase, lactate dehydrogenase, total antioxidant status (TAS) and G6PD activity with commercial kits. Results TAS was increased in the groups with alpha-T addition (groups C and D). Post-exercise, TAS and G6PD activity were remarkably higher (2.10 ± 0.13 mmol l −1, 7.92 ± 1.5 U g −1 Hb, respectively) in group D than those in group B (0.92 ± 0.10 mmol l −1, 4.8 ± 1.4 U g −1 Hb, p < 0.01, respectively). G6PD activity positively correlated with TAS ( r = 0.64, p < 0.001) in all the studied groups. Conclusions Supplementation with alpha-T may protect G6PD activity from reduction induced by forced training.

The effects of extracorporeal shock wave lithotripsy on antioxidant enzymes in erythrocytes

The effects of extracorporeal shock wave lithotripsy (ESWL) on patients undergoing ESWL for renal stone treatment have been studied using activities of glucose-6-phosphate dehydrogenase (G6PDH), superoxide dismutase (SOD) and catalase (CAT), and levels of malondialdehyde (MDA) in the erythrocyte haemolysate. The study included 23 patients (eight women, 15 men with an age range of 23-57 years). Blood samples were taken 5 min before ESWL, in addition to 1 h and 5 days after termination of treatment. Enzyme activities and MDA levels in erythrocytes were measured spectrophotometrically. When compared with the values obtained before ESWL, erythrocyte G6PDH (p = 0.015), SOD (p = 0.036) and CAT (p = 0.01) activities were found to be significantly reduced at the first hour after ESWL. On the fifth day after ESWL, erythrocyte enzyme activities were normalized to the values obtained before ESWL. Although there was a significant difference between values before and 1 h after ESWL (p = 0.003), no difference was detected between 1 h after ESWL and 5 days after ESWL (p > 0.05) in terms of MDA values. The findings of the present study revealed that erythrocyte lipid peroxidation might be induced and antioxidative defence mechanism may be transiently impaired by ESWL.

Cyclosporine A‐Induced Changes to Erythrocyte Redox Balance is Time Course‐Dependent

Cyclosporine A-treated transplant recipients develop pronounced cardiovascular disease and have increased oxidative stress and altered antioxidant capacity in erythrocytes and plasma. These experiments investigated the time-course of cyclosporine A-induced changes to redox balance in plasma and erythrocytes. Rats were randomly assigned to either a control or cyclosporine A-treated group. Treatment animals received 25 mg/kg of cyclosporine A via intraperitoneal injection for either 7 days or a single dose. Control rats were injected with the same volume of the vehicle. Three hours after the final injections, plasma was analysed for total antioxidant status, alpha-tocopherol, malondialdehyde, and creatinine. Erythrocytes were analysed for reduced glutathione (GSH), alpha-tocopherol, methaemoglobin, malondialdehyde, and the activities of superoxide dismutase, catalase, GSH peroxidase, and glucose-6-phosphate dehydrogenase (G6PD). Cyclosporine A administration for 7 days resulted in a significant increase (P<0.05) in plasma malondialdehyde, methaemoglobin, and superoxide dismutase and catalase activities. There was a significant decrease (P<0.05) in erythrocyte GSH concentration and G6PD activity in cyclosporine A animals. There were no significant differences (P>0.05) between groups following a single dose of cyclosporine A in any of the measures. In summary, cyclosporine A alters erythrocyte redox balance after 7 days administration, but not after a single dose.

Sublethal ammonia and urea concentrations inhibit rainbow trout ( Oncorhynchus mykiss) erythrocyte glucose-6-phosphate dehydrogenase

In vitro and in vivo effects of sublethal ammonia and urea concentrations were assayed on glucose-6-phosphate dehydrogenase (G6PD) of rainbow trout ( Oncorhynchus mykiss) erythrocyte. G6PD was purified from erythrocytes with a specific activity of 16.7 EU (mmol NADP +/min)/mg protein and ∼1600-fold in a yield of ∼60% by ammonium sulphate precipitation and 2′,5′-ADP Sepharose 4B affinity chromatography. The purity of the enzyme was confirmed using SDS polyacrylamide gel electrophoresis. Experiments with ammonia (2.2–5.5 μM) and urea (20–50 μM) showed the inhibitory effects on the enzyme, in vitro. Inhibition effects were determined in vitro by Lineweaver–Burk and regression graphs. The dissociation constant of the enzyme inhibitor complex ( K i) and 50% inhibitory values were 2.26 ± 1.21 and 2.86 ± 3.51 μM for ammonia and 18.69 ± 6.75 and 23.77 ± 4.58 μM for urea, respectively. In vivo studies in rainbow trout erythrocytes showed significant ( p < 0.01) inhibition of G6PD by ammonia and urea. However, ammonia inhibited more than urea since there were significant differences between the final values of erythrocyte G6PD activities.

Glucose-6-phosphate Dehydrogenase Deficiency in Neonatal Indirect Hyperbilirubinemia

The aim of this article is to investigate the prevalence of Glucose-6-phosphate dehydrogenase (G6PD) deficiency in neonatal hyperbilirubinemia and to compare the clinical presentation and course of G6PD-deficient and normal patients. This study included a total of 624 term neonates with indirect hyperbilirubinemia from March 2001 to September 2004. Birth weight, sex, weight at admission, serum bilirubin at admission, maximum bilirubin, phototherapy duration, duration of hospitalization and the need for exchange transfusion were recorded. Laboratory evaluations included blood group typing of mother and newborn, complete blood count, peripheral blood smear, serum total and direct bilirubin, direct coombs test, reticulocyte count, serum-free T4 and TSH, urine analysis, urinary reducing substance and erythrocyte G6PD level. The analysis of the results indicated that 24 neonates with indirect hyperbilirubinemia were G6PD-deficient. No statistically significant difference was detected between G6PD-deficient and normal groups in relation to the time of onset of jaundice, reticulocyte count, hematocrit level, phototherapy duration and duration of hospitalization. Serum bilirubin at admission, maximum serum bilirubin level and the need for exchange transfusion were higher in G6PD-deficient group. From this study our conclusion is that the G6PD deficiency is a common enzyme defect causing severe indirect hyperbilirubinemia which may result in kernicterus. Early neonatal screening programmes should be instituted in countries where the deficiency is prevalent.

Cyclosporine A induced changes to plasma and erythrocyte antioxidant defences

Organ transplant recipients develop pronounced cardiovascular disease, and decreased antioxidant capacity in plasma and erythrocytes is associated with the pathogenesis of this disease. These experiments tested the hypothesis that the immunosuppressant cyclosporine A (CsA) alters erythrocyte redox balance and reduces plasma antioxidant capacity. Female Sprague-Dawley rats were randomly assigned to a control or CsA treated group. Treatment animals received 25 mg/kg/day of CsA via intraperitoneal injection for 18 days. Control rats were injected with the same volume of the vehicle. Three hours after the final CsA injection, rats were exsanguinated and plasma analysed for total antioxidant status (TAS), α-tocopherol, malondialdehyde (MDA), and creatinine. Erythrocytes were analysed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glucose-6-phosphate dehydrogenase (G6PD) activities, α-tocopherol, and MDA. CsA administration resulted in a significant (P < 0.05) decrease in plasma TAS and significant increases (P < 0.05) in plasma creatinine and MDA. Erythrocyte CAT was significantly (P < 0.05) increased in CsA treated rats compared to controls. There were no significant differences (P > 0.05) in erythrocyte SOD, GPX, G6PD, α-tocopherol or MDA between groups. In summary, CsA alters erythrocyte antioxidant defence and decreases plasma total antioxidant capacity.

Response of Elevated Serum Soluble Interleukin-2 Receptor (sIL-2R) and Overexpression of Glucose-6-Phosphate Dehydrogenase (G6PD) in Patients with Chronic Myelogenous Leukemia Treated with Imatinib Mesylate.

Regulation of intracellular redox potential is important for regulation of cell growth. G6PD functions to catalyze the first step in the pentose phosphate pathway physiologically providing the NADPH required for reductive biosynthesis and detoxification of free-radicals and peroxides in mature red blood cells. We present two cases of patients (pts) with Chronic Myelogenous Leukemia-chronic phase (CML-cp) with significant overexpression of sIL-2R and G6PD. Serum elevated levels of sIL-2R and G6PD correlated to CML stage and response to therapy with imatinib; one male pt and one female pt with white blood cell counts of 80 and 21,000 X 109 per liter and a mean sIL-2R and G6PD levels of 26.975 X 103 pg/ml and 14.10 units/gHb respectively. Both pts had BCR/abl-RT-PCR positive gene rearrangements with b2a2 in peripheral blood and bone marrow. Chromosomal abnormalities of female pt was consistent with CML-cp (t 9; 22) ( q34;q11.2) philadelphia chromosome. Treatment of both pts with imatinib 400 mg orally daily resulted in reduction toward normal levels of sIL-2R and G6PD. Our female pt had to have therapy interrupted due to severe gastrointestinal and myelosuppression with cardiac irritation, edema, headaches and arthralgia. She was changed to 300 mg of imatinib with a proton-pump inhibitor, growth factor G-CSF, and a cox-2 inhibitor with excellent tolerance and response to therapy ( see table I).Response of sIL-2R and G6PD To Treatment With Imatinib MesylateMONTHSLAP-SCOREsIL-2R (pg/ml)CRP (mg/dL)G6PD (units/gHb)LDH (U/L)Zero426,97516.011.1386Three125,6292.754.1241Six1712,8680.753.6266Twelve1436,1113.753.9203Lap Score(NL 40-130); sIL-2R (NL 1,770-9,753); G6PD (3.5–5.0)CONCLUSIONS: Overexpression of sIL-2R and G6PD in CML-cp pts treated with tyrosine kinase inhibitor imatinib mesylate were significantly reduced to levels within normal limits after twelve months of therapy. Peripheral blood sera sIL-2R and erythrocyte G6PD levels in CML-cp pts may be useful clinical and prognostic indicators of leukemic cell burden.

Diurnal fluctuation of leukocyte G6PD activity. A possible explanation for the normal neutrophil bactericidal activity and the low incidence of pyogenic infections in patients with severe G6PD deficiency in Israel.

Acute hemolytic anemia associated with red blood cell (RBC) glucose-6-phosphate dehydrogenase (G6PD) deficiency is commonly encountered in the Mediterranean basin. Nevertheless, concomitant clinical evidence of white blood cell G6PD deficiency is extremely rare in Israel. This study sought to assess simultaneously levels of G6PD activity in polymorphonuclear leukocytes (PMN) and in red blood cells (RBC) of patients with G6PD deficiency, including full-term newborn infants. In PMN, the correlation between G6PD activity, hexose monophosphate shunt activity, and superoxide anion release was evaluated. In G6PD-deficient patients, a parallel and significantly decreased G6PD activity was found in neutrophils (range of activity 0-4.5 IU/10(6) PMN) and erythrocytes (range of activity 0-1.8 IU/g Hb), compared with healthy controls (5-23 IU/10(6) PMN and 2.4-6.4 IU/g Hb, respectively). A positive correlation was found in PMN between the levels of G6PD activity, hexose monophosphate (HMP) shunt activity, and superoxide anion release (p < 0.01). Nevertheless, all patients' bactericidal activity of neutrophils remained in the range of healthy controls. Although many episodes of acute hemolytic anemia were recorded, no increased incidence of pyogenic infections was observed in any group of patients investigated. Neutrophil and erythrocyte G6PD levels were re-assessed in some of these patients several times a day. A significant diurnal fluctuation of the enzyme activity was found. It is speculated that the patients produce fluctuating daily quantities of NADPH, sufficient to initiate the neutrophil respiratory burst and to achieve normal bactericidal activity, necessary to prevent the development of microbial infections.

Purification of human erythrocyte glucose 6-phosphate dehydrogenase and glutathione reductase enzymes using 2 ′,5 ′-ADP Sepharose 4B affinity column material in single chromatographic step

The enzymes of glucose 6-phosphate dehydrogenase and glutathione reductase were purified from human erythrocytes in one chromatographic step consisting of the use of the commercially available resin 2 ′,5 ′-ADP Sepharose 4B by using different washing buffers. Ammonium sulfate (30–70%) precipitation was performed on the hemolysate before applying to the affinity column. Using this procedure, G6PG, having the specific activity of 22.9 EU/mg proteins, was purified with a yield of 43% and 9150-fold; GR, having the specific activity of 20.7 EU/mg proteins, was purified with a yield of 26% and 8600-fold. The purity of the enzymes was checked on sodium dodecyl sulfate–polyacrylamide gel electrophoresis and each purified enzyme showed a single band on the gel. This procedure has advantages of preventing of enzyme denaturation, short experimental duration, and use of less chemical materials for purification of the enzymes.

Glutathion Peroxidase and Glucose-6-Phosphate Dehydrogenase Activities in Bovine Blood and Liver

A total of 46 cattle, including 25 as control, 16 with glycogen degeneration and 5 with severe fatty degeneration were studied. Whole blood and liver tissue specimens were used to measure glutathione peroxidase (GSH-Px) and Glucose-6-Phosphate Dehydrogenase (G6PD) activities. The present study determined the value of these parameters in diagnosing glycogen and fatty degeneration in cattle from the point of the status of antioxidation and lipid peroxidation. The results showed a significant decrease in hepatic GSH-Px activity and a significant increase in hepatic G6PD activity in cases of fatty degeneration. On the other hand, there were no significant changes in erythrocytic and hepatic GSH-Px and G6PD activities in cases of glycogen degeneration. The results indicated lipoperoxidation process in the liver tissues increased in cases of fatty degeneration. Therefore, supplying animals suffering from fatty liver with sufficient quantities of nutrient antioxidants may be valuable when treatment is considered.

Quantitative evolutionary design of glucose 6-phosphate dehydrogenase expression in human erythrocytes.

Why do the activities of some enzymes greatly exceed the flux capacity of the embedding pathways? This is a puzzling open problem in quantitative evolutionary design. In this work we investigate reasons for high expression of a thoroughly characterized enzyme: glucose 6-phosphate dehydrogenase (G6PD) in human erythrocytes. G6PD catalyses the first step of the pathway that supplies NADPH for antioxidant defense mechanisms. Normal G6PD activity far exceeds the capacity of human erythrocytes for a steady NADPH supply, which is limited upstream of G6PD. However, the distribution of erythrocyte G6PD activity in human populations reveals a selective pressure for maintaining high activity. To clarify the nature of this selective pressure, we studied how G6PD activity and other parameters in a model of the NADPH redox cycle affect metabolic performance. Our analysis indicates that normal G6PD activity is sufficient but not superfluous to avoid NADPH depletion and ensure timely adaptation of the NADPH supply during pulses of oxidative load such as those that occur during adherence of erythrocytes to phagocytes. These results suggest that large excess capacities found in some biochemical and physiological systems, rather than representing large safety factors, may reflect a close match of system design to unscrutinized performance requirements. Understanding quantitative evolutionary design thus calls for careful consideration of the various performance specifications that biological components/processes must meet in order for the organism to be fit. The biochemical systems framework used in this paper is generally applicable for such a detailed examination of the quantitative evolutionary design of gene expression levels in other systems.

The effects of ethanol on glucose 6-phosphate dehydrogenase enzyme activity from human erythrocytes in vitro and rat erythrocytes in vivo.

The effects of ethanol on erythrocyte glucose 6-phosphate dehydrogenase (G6PD) activity were investigated under in vitro and in vivo conditions. For in vitro studies, glucose 6-phosphate dehydrogenase was purified from human erythrocyte and rats were used for in vivo studies. Enzyme activity was determined spectrophotometrically by the Beutler method. The in vitro study showed that the I(50) value was 17 mM for ethanol. In the case of the in vivo study, a 2 ml/kg dose of ethanol significantly inhibited the G6PD activity. The inhibition rate after ethanol administration was 59%, 40% and 6% at 1, 3 and 6 h after, respectively. The results of this study suggest that ethanol has a significant inhibitory effect on the G6PD activity both in vivo and in vitro.

Hematologically Important Mutations: Glucose-6-phosphate Dehydrogenase

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic trait that can cause hemolytic anemia. To date, over 150 nonsynonymous mutations have been identified in G6PD, with pathogenic mutations clustering near the dimer and/or tetramer interface and the allosteric NADP+-binding site. Recently, our lab identified a small molecule that activates G6PD variants by stabilizing the allosteric NADP+ and dimer complex, suggesting therapeutics that target these regions may improve structural defects. Here, we elucidated the connection between allosteric NADP+ binding, oligomerization, and pathogenicity to determine whether oligomer stabilization can be used as a therapeutic strategy for G6PD deficiency (G6PDdef). We first solved the crystal structure for G6PDK403Q, a mutant that mimics the physiological acetylation of wild-type G6PD in erythrocytes and demonstrated that loss of allosteric NADP+ binding induces conformational changes in the dimer. These structural changes prevent tetramerization, are unique to Class I variants (the most severe form of G6PDdef), and cause the deactivation and destabilization of G6PD. We also introduced nonnative cysteines at the oligomer interfaces and found that the tetramer complex is more catalytically active and stable than the dimer. Furthermore, stabilizing the dimer and tetramer improved protein stability in clinical variants, regardless of clinical classification, with tetramerization also improving the activity of G6PDK403Q and Class I variants. These findings were validated using enzyme activity and thermostability assays, analytical size-exclusion chromatography (SEC), and SEC coupled with small-angle X-ray scattering (SEC-SAXS). Taken together, our findings suggest a potential therapeutic strategy for G6PDdef and provide a foundation for future drug discovery efforts.

Blood and lens lipid peroxidation and antioxidant status in normal individuals, senile and diabetic cataractous patients

Purpose. Oxidative mechanisms are believed to play an important role in the pathogenesis of cataract, the most important cause of visual impairment at advanced age. To determine the body's antioxidant status as well as its lipid peroxidation levels, both blood and lens parameters were evaluated. Methods. This study was performed on the blood samples and lenses obtained from 46 patients diagnosed as having cataract and 20 control subjects. The control group was composed of 10 women and 10 men who do not smoke. Control subjects without any lens opacity or vacuoles when observed with a slit lamp were recruited on the same exclusion criteria as far as disease and treatment were concerned. No antioxidant medicines were used. They were all healthy individuals without any systemic diseases. Superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD), glutathione reductase (GSSG-Red) activities in red blood cell (RBC) lysates as well as whole blood glutathione (GSH) and plasma thiobarbituric acid reactive substances (TBARS), the indicator of lipid peroxidation concentrations, were determined quantitatively both in the blood samples and the lenses of the patients with senile and diabetic cataracts. Results. Whole blood GSH values, and erythrocyte SOD activities were significantly lower in the cataractous patients than those in the control group. The values in the diabetic cataractous group were also less than those in the senile cataractous group. Significantly decreased erythrocyte GSSG-Red and G6PD activities were detected in the diabetic cataractous group. Plasma TBARS values were higher both in the senile and diabetic groups when compared to those in the control group. Significantly decreased values were observed for GSSG-Red activities and TBARS values in the lenses of the senile cataractous patients in comparison with those in the diabetic cataractous patients. The lens GSH values were found to be higher in the senile cataractous group than the values obtained in the diabetic cataractous group. Conclusions. A strong correlation was found between lens GSH and lens TBARS concentrations in the diabetic group. This emphasized the vital role of GSH as an antioxidant in the lens over the other antioxidant parameters, e.g., enzymes, and the oxidative stress is at the highest level in lens.

Kinetic analysis of multi enzyme systems: A case study of the closed system of creatine kinase, hexokinase and glucose 6-phosphate dehydrogenase

This paper describes a general methodology to handle closed multi enzyme systems using mixture of symbolic (which depends on the Grobner Basis technique) and numerical computation methods. The applicability of the proposed method has been examined for the closed three-enzyme system of rabbit heart creatine kinase (EC 2.7.3.2), yeast hexokinase (EC 2.7.1.1) and human erythrocyte glucose 6-phosphate dehydrogenase (EC 1.1.1.49) using experimental data.

Effects of metamizol and magnesium sulfate on enzyme activity of glucose 6-phosphate dehydrogenase from human erythrocyte in vitro and rat erythrocyte in vivo

Objective: Effects of metamizol and magnesium sulfate on erythrocyte glucose 6-phosphate dehydrogenase enzyme activity were investigated in in vitro and in vivo conditions. Methods: For in vitro studies, glucose 6-phosphate dehydrogenase was purified from human erythrocyte and rats were used for in vivo studies. Enzyme activity was determined according to the Beutler method by using a spectrophotometer at 340 nm. Results: The results of in vitro study showed that their mean K i values were 6.35 × 10 −3 M for metamizol and 1.32 × 10 −2 M for magnesium sulfate and their inhibition types were uncompetitive. I 50 value was 17 mM for metamizol and 50 mM for magnesium sulfate in in vitro study. In the case of in vivo studies, 200 mg/kg metamizol inhibited the enzyme activity by 40% during the first 1.5 h ( p < 0.05), and 225 mg/kg magnesium sulfate significantly inhibited the enzyme activity throughout 24 h ( p < 0.01). Conclusion: The results of this study suggested that metamizol and magnesium sulfate have significant inhibition effect on the activity of glucose 6-phosphate dehydrogenase enzyme in both in vivo and in vitro.

Evaluation of Erythrocyte G6PD Activity Unit; It is Better Defined as a Function of RBC Count

Glucose 6-phosphate dehydrogenase (G6PD) deficiency, one of the most common red celi abnormalities, is characterized by wide clinical, biochemical and molecular heterogeneity. in clinical laboratories erythrocyte ·G6PD activity is defined either as a function of hemoglobin (Hb) concentration or red blood celi (RBC) count and seldom hematocrit (Hct). These parameters are variable tor every individual and misinterpretation of the results cannot be avoided with reference interval establishment studies unless the best approach that define erythrocyte G6PD activity is selected. Hb concentration is frequently prone to the effects of genetic, physiological and environmental factors where G6PD activity should correlate with RBC count even when it is altered. in this study relations of the erythrocyte G6PD activity with RBC count, Hb concentration of the erythrocyte suspensions and RBC indices of 242 individuals were studied. Additionally, relations with platelet and white blood celi (WBC) counts were evaluated to determine possible interference. Erythrocyte G6PD activity was determined with kinetic spectrophotometric method according to the ICSH at 3o0 c. RBC, WBC, platelet counts, hemoglobin concentration of the erythrocyte suspensions and erythrocyte indices were determined with an automatic complete blood counter. Enzyme activity was correlated with RBC count (r: 0.53, p&lt;0.001), there was no correlation with Hb (p&gt;0.05). The negative correlation of the enzyme activity with MCV and MCH (r: -0.44 and r: -0.29, p&lt;0.001 ), disappeared as a ratio of RBC count (p&gt;0.05) and strengthened as a ratio of Hb concentration (r: -0.61 and r: -0.44, p&lt;0.001 ). in this study a correlation of erythrocyte suspentions' platelet, leucocyte count and the enzyme activity as a ratio of Hb (r: 0.33 and r: 0.25, p&lt;0.001) was observed. On the other hand enzyme activity as a ratio of RBC was only poorly correlated to WBC count (r: 0.15, p&lt;0.01 ). Results of this study indicate that erythrocyte G6PD activity is related to RBC count and has several advantages over Hb in assessing G6PD status. it gives more reliable results in conditions that could affect erythrocyte morphology and Hb concentration.