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

A live bacteria enzyme assay for identification of human disease mutations and drug screening

Advances in high-throughput sequencing have enabled the identification of genetic variations associated with human disease. However, deciphering the functional significance of these variations remains challenging. Here we propose an alternative approach that uses humanized Escherichia coli to study human genetic enzymopathies and to screen candidate drug effects on metabolic targets. By replacing selected E. coli metabolic enzymes with their human orthologues and their sequence variants, we demonstrate that the growth rate of E. coli reflects the in vivo activity of heterologously expressed human enzymes. This approach accurately reflected enzyme activities of known sequence variants, enabling rapid screening of causal sequence variations associated with human diseases. This approach bridges the gap between in vitro assays and cell-based assays. Our findings suggest that the proposed approach using a humanized E. coli strain holds promise for drug discovery, offering a high-throughput and cost-effective platform for identifying new compounds targeting human enzymes. Continued research and innovation in this field have the potential to impact the development and practice of precision medicine.

In Vitro Effects of Some Chemotherapeutics on Human Erythrocyte Glucose-6-Phosphate Dehydrogenase Enzyme

In this study; the in vitro effects of some drugs used in chemotherapy on the glucose-6-phosphate dehydrogenase enzyme (G6PD; E.C. 1.1.1.49) purified from human erythrocyte lysate were investigated. In the first stage of the study, G6PD enzyme was purified from human erythrocyte lysate (with a specific activity of 0.243 EU/mg protein, 68.75% yield and 162 purificaion fold) by ammonium sulfate precipitation and 2', 5' Adenosine diphosphate (ADP)-Sepharose 4B gel affinity chromatography. The purity of the enzyme was checked by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In the second stage of the study, the in vitro effects of some chemotherapy drugs such as ibandronic acid, fluorouracil, oxaliplatin, carboplatin, cyclophosphamide, doxorubicin, metoart con and cisplatin on the activity of the purified enzyme were investigated. As a result of the in vitro studies, the drugs ibandronic acid, oxaliplatin and carboplatin, have an inhibitory effect on the enzyme, and IC50 values were calculated as 1.34, 2.05, and 2.43 mM, respectively. In addition, in order to determine the K i constants and inhibition types for the drugs oxaliplatin and carboplatin, activity measurements were made at five different substrates and three fixed inhibitor concentrations and Lineweaver-Burk graphs were drawn. With the help of these graphs, the K i constant of oxaliplatin was determined as 19.46 ± 3.38 mM and the K i constant of carboplatin was 22.37 ± 3.19 mM. It was determined that the inhibition type of both drugs was competitive. It was determined that the drugs fluorouracil, cyclophosphamide, doxorubicin, metoart con, and cisplatin did not have a significant effect on the enzyme activity.

The Effects of Sodium Tetraborate against Lead Toxicity in Rats: The Behavior of Some Metabolic Enzymes

This study was planned to research the in vivo effects of lead (Pb) ions and sodium tetraborate (Na2B4O7) on G6PD and 6PGD, which are some of the enzymes of the pentose phosphate pathway, which carries vital importance for metabolism, and GR and GST, which are glutathione metabolism enzymes, and the in vitro effects of the same agents on the 6PGD enzyme. According to the in vivo analysis results, in comparison to the control group, the rat liver G6PD (p < 0.05), and 6PGD (p < 0.01) enzyme activities in the Na2B4O7 group were significantly lower. In addition, GR and GST enzyme activities were insignificantly lower in the Na2B4O7 group compared to the control group (p > 0.05). The Pb group had lower G6PD and 6PGD enzyme activity levels and higher GR and GST enzyme activity levels compared to the control group, while these changes did not reach statistical significance (p > 0.05). In the in vitro analyses of the effects of Pb ions on the 6PGD enzyme that was purified out of rat liver with the 2',5'-ADP-Sepharose 4B affinity chromatography method, it was determined that Pb ions (200-1200 μM) increased the rat liver 6PGD enzyme activity levels by 33%. On the other hand Na2B4O7 was not significantly effective on 6PGD activity. These results will also contribute to future studies in understanding the physiopathology of the states triggered by Pb ions and sodium tetraborate (Na2B4O7).

The complex combination of COVID-19 and diabetes: pleiotropic changes in glucose metabolism

PURPOSE

Angiotensin converting enzyme 2 (ACE2) is the door for SARS-CoV-2, expressed in critical metabolic tissues. So, it is rational that the new virus causes pleiotropic alterations in glucose metabolism, resulting in the complication of pre-existing diabetes's pathophysiology or creating new disease mechanisms. However, it seems that less attention has been paid to this issue. This review aimed to highlight the importance of long-term consequences and pleiotropic alterations in glucose metabolism following COVID-19 and emphasize the need for basic and clinical research in metabolism and endocrinology.

RESULTS

SARS-CoV-2 shifts cellular metabolism from oxidative phosphorylation to glycolysis, which leads to a decrease in ATP generation. Together with metabolic imbalance, the impaired immune system elevates the susceptibility of patients with diabetes to this deadly virus. SARS-CoV-2-induced metabolic alterations in immune cells can result in hyper inflammation and a cytokine storm. Metabolic dysfunction may affect therapies against SARS-CoV-2 infection. The effective control of metabolic complications could prove useful therapeutic targets for combating COVID-19. It is also necessary to understand the long-term consequences that will affect patients with diabetes who survived COVID-19.

CONCLUSIONS

Since the pathophysiology of COVID-19 is still mostly unknown, identifying the metabolic mechanisms contributing to its progression is essential to provide specific ways to prevent and improve this dangerous virus's detrimental effects. The findings show that the new virus may induce new-onset diabetes with uncertain metabolic and clinical features, supporting a potential role of COVID-19 in the development of diabetes.

The effect of brimonidine and proparacaine on metabolic enzymes: Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase

Oxidative stress is to upregulate the pentose phosphate pathway (PPP). The PPP consists of two functional branches, glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconaste dehydrogenase (6PGD). Glutathione reductase (GR) has a significant role in catalyzing an oxidized glutathione form into a reduced form. The purpose of this study is to investigate the effects of brimonidine and proparacaine on the activity of 6PGD, G6PD, and GR enzymes purified from human erythrocytes. Brimonidine displayed considerable inhibition profile against G6PD with IC₅₀ value and K_I constant of 29.93 ± 3.56 and 48.46 ± 0.66 μM, respectively. On the other hand, proparacaine had no inhibitory effect against G6PD. K_I values were found to be 66.06 ± 0.78 and 811.50 ± 11.13 μM for brimonidine and proparacaine, respectively, for 6PGD. K_I values were found to be 144.10 ± 2.01 and 1,654.00 ± 26.29 μM for brimonidine and proparacaine, respectively, for GR. Herein, also in silico molecular docking studies were performed between drugs and enzymes.

Bioprocess optimization for pectinase production using Aspergillus niger in a submerged cultivation system

BACKGROUND

Pectinase enzymes present a high priced category of microbial enzymes with many potential applications in various food and oil industries and an estimated market share of $ 41.4 billion by 2020.

RESULTS

The production medium was first optimized using a statistical optimization approach to increase pectinase production. A maximal enzyme concentration of 76.35 U/mL (a 2.8-fold increase compared with the initial medium) was produced in a medium composed of (g/L): pectin, 32.22; (NH4)2SO4, 4.33; K2HPO4, 1.36; MgSO4.5H2O, 0.05; KCl, 0.05; and FeSO4.5H2O, 0.10. The cultivations were then carried out in a 16-L stirred tank bioreactor in both batch and fed-batch modes to improve enzyme production, which is an important step for bioprocess industrialization. Controlling the pH at 5.5 during cultivation yielded a pectinase production of 109.63 U/mL, which was about 10% higher than the uncontrolled pH culture. Furthermore, fed-batch cultivation using sucrose as a feeding substrate with a rate of 2 g/L/h increased the enzyme production up to 450 U/mL after 126 h.

CONCLUSIONS

Statistical medium optimization improved volumetric pectinase productivity by about 2.8 folds. Scaling-up the production process in 16-L semi-industrial stirred tank bioreactor under controlled pH further enhanced pectinase production by about 4-folds. Finally, bioreactor fed-batch cultivation using constant carbon source feeding increased maximal volumetric enzyme production by about 16.5-folds from the initial starting conditions.

Biochemical characterization of buffalo liver glucose-6-phosphate dehydrogenase isoforms

Glucose-6-phosphate dehydrogenase (G6PD) is a key regulatory enzyme involved in the pentose phosphate pathway. This works represents purification of two buffalo liver glucose-6-phosphate dehydrogenases (BLG6PD1 and BLG6PD2) using combination of ammonium sulfate precipitation and several chromatographic columns. Both enzymes (BLG6PD1 and BLG6PD2) were homogenous on both native PAGE as well as 12% SDS PAGE with molecular weights of 28 and 66 kDa. The molecular weight of BLG6PD1 and BLG6PD2 native forms were determined to be 28 and 66 kDa by gel filtration; indicating monomeric proteins. The K(m) values for BLG6PD1 and BLG6PD2 estimated to be 0.059 and 0.06 mM of β-nicotinamide adenine dinucleotide phosphate. The optimum activity of BLG6PD1 and BLG6PD2 were displayed at pH 8.0 and 8.2 with an isoelectric point (pI) of pH 7.7-7.9 and 5.7-5.9. The divalent cations MgCl2, and CoCl2 act as activators, on the other hand, FeCl2, CuCl2 and ZnCl2 are potent inhibitors of BLG6PD1 and BLG6PD2 activity. NADPH inhibited both isoenzymes competitively with Ki values of 0.012 and 0.030 mM. This study describes a reproducible purification scheme of G6PD from the liver of buffalo as a rich source.

Purification and characterization of glucose-6-phosphate dehydrogenase from camel liver

Glucose-6-phosphate dehydrogenase from camel liver was purified to homogeneity by ammonium sulfate precipitation and a combination of DEAE-cellulose, Sephacryl S-300 gel filtration, and 2', 5' ADP Sepharose 4B affinity chromatography columns. The specific activity of camel liver G6PD is increased to 1.80438 units/mg proteins with 63-fold purification. It turned out to be homogenous on both native PAGE and 12% SDS PAGE, with a molecular weight of 64 kDa. The molecular weight of the native form of camel liver G6PD was determined to be 194 kDa by gel filtration indicating a trimeric protein. The K m value was found to be 0.081 mM of NADP(+). Camel liver G6PD displayed its optimum activity at pH 7.8 with an isoelectric point (pI) of pH 6.6-6.8. The divalent cations MgCl2, MnCl2, and CoCl2 act as activators; on the other hand, CaCl2 and NiCl2 act as moderate inhibitors, while FeCl2, CuCl2, and ZnCl2 are potent inhibitors of camel liver G6PD activity. NADPH inhibited camel liver G6PD competitively with K i value of 0.035 mM. One binding site was deduced for NADPH on the enzyme molecule. This study presents a simple and reproducible purification procedure of G6PD from the camel liver.

In vitro inhibition effects of some coumarin derivatives on human erythrocytes glucose-6-phosphate dehydrogenase activities

Inhibitory effects of some synthesized dihydroxycoumarin compounds on purified G6PD were investigated. For this purpose, initially human erythrocyte G6PD was purified 7069-fold in a yield of 33.6% by using ammonium sulfate precipitation and affinity chromatography which includes 2',5'-ADP Sepharose 4B. The purified enzyme showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Enzyme activity was determined spectrophotometrically according to Beutler method at 340 nm. 6,7-Dihydroxy-3-(2-methylphenyl)-2H-chromen-2-one (OPC), 6,7-dihydroxy-3-(3-methylphenyl)-2H-chromen-2-one (MPC) and 6,7-dihydroxy-3-(4-methylphenyl)-2H-chromen-2-one (PPC) were used as dihydroxycoumarin compounds. This study has demonstrated that G6PD activity is very highly sensitive to study coumarin derivatives.

Purification of rat kidney glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase enzymes using 2',5'-ADP Sepharose 4B affinity in a single chromatography step

The enzymes of glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and glutathione reductase (GR) were purified from rat kidney in one chromatographic step consisting of the use of the 2',5'-ADP Sepharose 4B by using different elution buffers. This purification procedure was accomplished with the preparation of the homogenate and affinity chromatography on 2',5'-ADP Sepharose 4B. The purity and subunit molecular weights of the enzymes were checked on SDS-PAGE and purified enzymes showed a single band on the gel. The native molecular weights of the enzymes were found with Sephadex G-150 gel filtration chromatography. Using this procedure, G6PG, having the specific activity of 32 EU/mg protein, was purified 531-fold with a yield of 88%; 6PGD, having the specific activity of 25 EU/mg protein, was purified 494-fold with a yield of 73%; and GR, having the specific activity of 33 EU/mg protein, was purified 477-fold with a yield of 76%. Their native molecular masses were estimated to be 144 kDa for G6PD, 110 kDa for 6PGD, and 121 kDa for GR and the subunit molecular weights were found to be 68, 56, and 61 kDa, respectively. A new modified method to purify G6PD, 6PGD, and GR, namely one chromatographic step using the 2',5'-ADP Sepharose 4B, is described for the first time in this study. This procedure has several advantages for purification of enzymes, such as, rapid purification, produces high yield, and uses less chemical materials.

Investigation of the Mutation Points and Effects of Some Drugs on Glucose-6-phosphate Dehydrogenase-deficient People in the Erzurum Region

We have carried out a systematic study of the molecular basis of glucose-6-phosphate dehydrogenase (G6PD) deficiency on three samples of 1,183 children aged 0.5-6 years from Erzurum, in eastern Anatolia. Total genomic DNAs were isolated from the blood samples of a healthy person and the three persons determined with G6PD deficiency by examining the enzyme activity and hemoglobin ratio. Then PCR amplification of the entire coding region in eight fragments was carried out followed by Agarose gel electrophoresis. The 540-bp PCR fragment containing exons VI-VII and the 550bp PCR fragment containing exons XI-XIII were digested with EcoRI and with NIaIII, respectively. SSCP techniques for eight fragments (exons II, III-IV, V, VI-VII, VIII, IX, X, and XI-XIII) were employed to determine the mutations on the exons of the G6PD gene. A mutation occurred on the region of the exons 6 and 7 of one person (person-1) and exon 5 of two G6PD-deficient persons (person 2 and 3) examined. The sequential approach described is fast and efficient and could be applied to other populations. Effects of analgesic drugs on G6PD were studied on the purified enzyme (ammonium fractionation, dialysis and 2',5' ADP-Sepharose 4B affinity chromatography) for the healthy person and G6PD-deficient persons 1, 2 and 3. The effects of remifentanil hydrochloride, fentanyl citrate, alfentanil hydrochloride and pethidine hydrochloride, as analgesic drugs, on G6PD activity were tested. Although remifentanil hydrochloride, fentanyl citrate (I50 values; 1.45mM and 6.1 mM, respectively) inhibited the activity of the enzyme belonging to the healthy person, they did not alter enzyme activity on two of the three persons with G6PD deficiency. Other drugs (alfentanil hydrochloride and pethidine hydrochloride) did not effect the enzyme activity of the healthy or G6PD-deficient children.

In vitroeffects of some drugs on catalase purified from human skin

Catalase enzyme (H202: oxidoreductase; E.C. 1.11.1.6) was purified from human skin homogenate using ammonium sulfate precipitation and DEAE-Sephadex A50 ion exchange chromatography at 4 degrees C and some characteristics of the enzyme were investigated. The human skin enzyme, having a specific activity of 1354.5 EU/mg proteins was purified with a yield of 43.13% and 1110-fold. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed a single band for the enzyme. Inhibition by piroxicam, ketoprofen, diclofenac sodium, sulfamethoxazole and nidazole occurred with I50 values of 0.414, 1.29, 1.8, 3.83, and 8.64 mM, respectively.

Effects of nicotine and vitamin E on 6-phosphogluconate dehydrogenase activity in some rat tissues in vivo and in vitro

The aim of this study was to investigate whether nicotine affects 6-phosphogluconate dehydrogenase (6PGD) enzyme activity in some rat tissues, and to see the modulatory effects of vitamin E on this effect in vivo. In addition, the effects of nicotine and vitamin E on 6PGD activity were also tested in vitro. The groups were: nicotine [0.5 mg/kg/day, intraperitoneal (i.p.)]; nicotine + vitamin E [75 mg/kg/day, intragastric (i.g.)]; and control group (receiving only vehicles). There were eight rats per group and supplementation period was 3 weeks. The results of in vivo study showed that nicotine activated the muscle, lungs, and testicular 6PGD enzyme activity but had no effect on heart and liver 6PGD activity. Also, nicotine + vitamin E activated the muscle, testicle, and liver 6PGD enzyme activity, while this combination had no effect on heart, and lungs in vivo. When nicotine is administered with vitamin E the increase in 6PGD enzyme activity in muscle and testicles were lower. On the other hand the increase in 6PGD enzyme activity was eliminated by vitamin E in lungs, while 6PGD enzyme activity was increased by vitamin E, which was not affected by nicotine only. In vitro results correlated well with in vivo experimental results. Our results suggest that vitamin E may favourably increase 6PGD enzyme activity in liver in nicotine treated rats, while it has negligible effects on this enzyme activity in other tissues.

Effects of some drugs on hepatic glucose 6-phosphate dehydrogenase activity in Lake Van fish (Chalcalburnus tarischii Pallas, 1811)

Inhibitory effects of some drugs on hepatic glucose 6-phosphate dehydrogenase from Lake Van fish (chalcalburnus tarischii pallas, 1811) were investigated. For this purpose, initially liver glucose 6-phosphate dehydrogenase was purified 899-fold in a yield of 46.24% by using 2',5'-ADP Sepharose 4B affinity gel. In order to control the purification of enzyme was done SDS polyacrylamide gel electrophoresis. SDS polyacrylamide gel electrophoresis showed a single band for enzyme. A constant temperature (+4 degrees C) was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340 nm. Vankomycine, sulfanylamide, sulfanylacetamide, nidazole, ciprofloxacin, amoxicillin and KMnO(4) were used as drugs. These drugs exhibited inhibitory effects on the enzyme. IC(50) values of vankomycine, sulfanylamide, sulfanylacetamide, nidazole, ciprofloxacin, amoxicillin and KMnO(4) were 1.88, 0.037, 0.032, 1.178, 2.26, 643.5 and 0.0002 mM, and the K(i) constants 1.18+/-0.148, 0.119+/-0.021, 0.075+/-0.015, 1.15+/-0.21, 7.69+/-0.67, 1007+/-69, and 0.001+/-0.00022 mM, respectively. While vankomycine and nidazole showed competitive inhibition, others displayed noncompetitive inhibition. K(i) constants and IC(50) values for drugs were determined by Lineweaver-Burk graphs and plotting activity percentage versus [I], respectively.

Effects of nicotine and vitamin E on glutathione reductase activity in some rat tissues in vivo and in vitro

Effects of nicotine, and nicotine+vitamin E on glutathione reductase (Glutathione: NADP(+) oxidoreductase, EC 1.8.1.7) activity in the muscle, heart, lungs, testicles, kidney, stomach, brain and liver tissues were investigated in vivo and also in vitro. The groups were: nicotine [0.5 mg/kg/day, intraperitoneal (i.p.)]; nicotine+vitamin E [75 mg/kg/day, intragastric (i.g.)]; and control group (receiving only vehicles). There were eight rats per group and supplementation period was 3 weeks. The results showed that nicotine (0.5 mg/kg, i.p.) inhibited glutathione reductase activity significantly in the liver, lungs, heart, stomach, kidney, and testicles by approximately 61.5%, approximately 65%, approximately 70.5%, approximately 72.5%, approximately 64% and approximately 71.5%, respectively, while it had activated glutathione reductase activity in the brain by approximately 11.8%, and had no effect on the muscle glutathione reductase activity. Vitamin E supplementation prevented this nicotine-induced decrease in glutathione reductase activity in liver, lungs, heart, stomach, and kidney. However, it did not prevent this nicotine-induced decrease in testicles. In vitro studies were also carried out to elucidate the effects of nicotine and vitamin E on glutathione reductase activity. In vitro results correlated well with in vivo experimental results in liver, lungs, heart, stomach, and testicular tissues. These results show that vitamin E administration generally restores the inactivation of glutathione reductase activity due to nicotine administration in various rat tissues in vivo, and also in vitro.

Irreversible inhibition of glucose-6-phosphate dehydrogenase by the coenzyme A conjugate of ketoprofen: a key to oxidative stress induced by non-steroidal anti-inflammatory drugs?

Oxidative damage by non-steroidal anti-inflammatory drugs (NSAIDs) has been considered relevant to the occurrence of gastro-intestinal side-effects. In the case of chiral arylpropionate derivatives like ketoprofen (KPF), this mechanism has been evidenced for the R-enantiomer, especially when chiral inversion was observed, and lets us suppose the involvement of CoA conjugates. Glucose-6-phosphate dehydrogenase (G6PD) is the crucial enzyme to regenerate the GSH pool and maintain the intracellular redox potential. This enzyme is known to be down-regulated by palmitoyl-CoA thioester. We hypothesised then that G6PD is the target of carboxylic NSAIDs, via their CoA metabolites. We used molecular docking to localise a putative site in the human G6PD then we chose the Yeast orthologue, as the most suitable species to study experimentally the precise molecular interaction. KPF-CoA was effectively shown to bind covalently to the unique cysteine residue of the yeast enzyme. Binding was found to occur in the same site as palmitoyl-CoA. It was decreased in the presence of an allosteric inhibitor of G6PD, phospho(enol)pyruvate, and was not detected with G6PD of Leuconostoc mesenteroides, which does not possess the allosteric site. This site is distinct from the catalytic site, and probably allosteric, explaining the observed non-competitive inhibition of its activity by KPF-CoA. KPF-CoA was shown to induce the production of reactive oxygen species in Caco-2 cells, where its inhibition of G6PD activity was observed.

Effects of some drugs on the activity of glucose 6-phosphate dehydrogenase from rainbow trout (Oncorhynchus mykiss) erythrocytes in vitro

Inhibitory effects of some drugs on glucose 6-phosphate dehydrogenase from the erythrocytes of rainbow trout (Oncorhynchus mykiss Walbaum, 1792) were investigated. The enzyme was purified 2488-fold in a yield of 76.8% using ammonium sulfate precipitation and 2',5'-ADP Sepharose 4B affinity gel at 4 degrees C. The drugs pental sodium, MgSO4, vancomycin, metamizol, marcaine, and prilocaine all exhibited inhibitory effects on the enzyme. While MgSO4 (K(i) = 12.119 mM), vancomycin (K(i) = 1.466 mM) and metamizol (K(i) = 0.392 mM) showed competitive inhibition, pental sodium (K(i) = 0.748 mM) and marcaine (K(i) = 0.0446 mM) displayed noncompetitive inhibition.

Chemical and pathological oxidative influences on band 3 protein anion-exchanger

BACKGROUND/AIMS

The erythrocyte is a cell exposed to a high level of oxygen pressure and to oxidative chemical agents. This stress involves SH-groups oxidation, cell shrinkage by activation of K-Cl co-transport (KCC) and elevation of the band 3 tyrosine phosphorylation level. The aim of our study was to test whether oxidative stress could influence band 3-mediated anion transport in human red blood cells.

METHODS

To evaluate this hypothesis, normal and pathological (glucose 6 phosphate dehydrogenase (G6PDH) defficient) erythrocytes were treated with known sulphydryl-blocking or thiol-oxidizing agents, such as N-ethylmaleimide (NEM), azodicarboxylic acid bis[dimethylamide] (diamide), orthovanadate, Mg2+ and tested for sulphate (SO4-) uptake, K+ efflux, G6PDH activity and glutathione (GSH) concentration.

RESULTS

In normal red blood cells, the rate constants of SO4- uptake decreased by about 28 % when cells were incubated with NEM, diamide and orthovanadate. In G6PDH-deficient red blood cells, in which oxidative stress occurs naturally, the rate constant of sulphate uptake was decreased by about 40% that of normal red cells. Addition of oxidizing and phosphatase inhibitor agents to pathological erythrocytes further decreased anion transport. In contrast, G6PDH activity was increased under oxidative stress in normal as well as in pathological cells and was lower in the presence of exogenous Mg2+ in parallel to a significant increase in sulphate transport. In both cells, the oxidizing agents increased K+ efflux with depletion of GSH.

CONCLUSION

The data are discussed in light of the possible opposite effects exerted by oxidative agents and Mg2+ on KCC and on the protein tyrosine kinase (PTK)-protein tyrosine phosphatase (PTP) equilibrium. The decreased sulphate uptake observed in the experimental and pathological conditions could be due to band 3 SH-groups oxidation or to oxidative stress-induced K-Cl symport-mediated cell shrinkage with concomitant band 3 tyrosine phosphorylation.

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.

Purification of glucose 6-phosphate dehydrogenase from Buffalo (Bubalus bubalis) erythrocytes and investigation of some kinetic properties

Glucose 6-phosphate dehydrogenase (G6PD) was purified from buffalo (Bubalus bubalis) erythrocytes and some characteristics of the enzyme were investigated. The purification procedure was composed of two steps: hemolysate preparation and 2('),5(')-ADP-Sepharose 4B affinity gel chromatography. Thanks to the two consecutive procedures, the enzyme, having a specific activity of 69.7EU/mg proteins, was purified 650-fold with a yield of 31%. Optimal pH, stable pH, optimal temperature, molecular weight, and K(M) and V(max) values for NADP(+) and glucose 6-phosphate (G6-P) substrates were also determined for the enzyme. In addition, K(i) values and the type of inhibition were determined by means of Lineweaver-Burk graphs obtained for such inhibitors as ATP, ADP, NADPH, and NADH.

The effects of some antibiotics on sheep lens glucose 6-phosphate dehydrogenase in vitro

PURPOSE

To investigate the in vitro effects of gentamicin sulfate, vancomycin hydrochloride, sodium cefazolin and ceftriaxone on glucose 6-phosphate dehydrogenase enzyme (G6PD) purified from sheep lenses.

METHODS

G6PD was purified from sheep lenses with a yield of 66.8% and a specific activity of 7.8 U/mg proteins, and 10,400-fold using ammonium sulfate fractionation and 2',5'-ADP Sepharose 4B affinity gel. The enzyme activity was determined by Beutler's method.

RESULTS

Gentamicin sulfate and vancomycin hydrochloride strongly inhibited the enzyme in vitro. The concentrations causing 50% inhibition (IC50 were 15.34, and 8.0 mM, respectively. Conversely, cefazolin sodium strongly activated this enzyme, and ceftriaxone caused milder activation.

CONCLUSIONS

If a patient with G6PD deficiency requires gentamicin sulfate or vancomycin hydrochloride, routine ophthalmic did not inhibit this enzyme. Postmortem studies are now needed to investigate the activity of G6PD and how it is affected by these antibiotics.