On the molecular weight of human glucose 6-phosphate dehydrogenase

Purification and biochemical characterization of glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glutathione reductase from rat lung and inhibition effects of some antibiotics

G6PD, 6PGD and GR have been purified separately in the single step from rat lung using 2', 5'-ADP Sepharose 4B affinity chromatography. The purified enzymes showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weights of the enzymes were estimated to be 134 kDa for G6PD, 107 kDa for 6PGD and 121 kDa for GR by Sephadex G-150 gel filtration chromatography, and the subunit molecular weights was respectively found to be 66, 52 and 63 kDa by SDS-PAGE. Optimum pH, stable pH, optimum ionic strength, optimum temperature, KM and Vmax values for substrates were determined. Product inhibition studies were also performed. The enzymes were inhibited by levofloxacin, furosemide, ceftazidime, cefuroxime and gentamicin as in vitro with IC50 values in the range of 0.07-30.13 mM. In vivo studies demonstrated that lung GR was inhibited by furosemide and lung 6PGD was inhibited by levofloxacin.

Antioxidant potential of Cymbopogon citratus extract: alleviation of carbon tetrachloride-induced hepatic oxidative stress and toxicity

This study was aimed to evaluate the effect of Cymbopogon citratus against carbon tetrachloride (CCl(4))-mediated hepatic oxidative damage in rats. Rats were administrated with C. citratus extract (100, 200 and 300 mg/kg b.w.) for 14 days before the challenge of CCl(4) (1.2 ml/kg b.w. p.o) on 13th and 14th days. Hepatic damage was evaluated by employing serum biochemical parameters (alanine aminotransferase-ALT, aspartate aminotransferase-AST and lactate dehydrogenase-LDH), malondialdehye (MDA) level, reduced GSH and antioxidant enzymes (catalase: CAT, glutathione peroxidase: GPX, quinone reductase: QR, glutathione S-transferase: GST, glutathione reductase: GR, glucose-6-phosphate dehyrogenase: G6PD). In addition, CCl(4)-mediated hepatic damage was further evaluated by histopathological examination. However, most of these changes were alleviated by prophylactic treatment of animals with C. citratus dose dependently (p < 0.05). The protection was further evident through decreased histopathological alterations in liver. The results of the present study indicated that the hepatoprotective effect of C. citratus might be ascribable to its antioxidant and free radical scavenging property.

Effects of some drugs on human erythrocyte glucose 6-phosphate dehydrogenase: an in vitro study

Inhibitory effects of some drugs on glucose 6-phosphate dehydrogenase from the erythrocytes of human have been investigated. For this purpose, at the beginning, erythrocyte glucose 6-phosphate dehydrogenase was purified 2256 times in a yield of 44.22% by using ammonium sulphate precipitation and 2', 5'-ADP Sepharose 4B affinity gel. Temperature of +4°C was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340 nm. This method was utilized for all kinetic studies. Ketotifen, dacarbazine, thiocolchicoside, meloxicam, methotrexate, furosemide, olanzapine, methylprednizolone acetate, paricalcitol, ritodrine hydrochloride, and gadobenate-dimeglumine were used as drugs. All the drugs indicated the inhibitory effects on the enzyme. Ki constants for glucose 6-phosphate dehydrogenase were found by means of Lineweaver-Burk graphs. While methylprednizolone acetate showed competitive inhibition, the others displayed non-competitive inhibition. In addition, IC(50) values of the drugs were determined by plotting Activity% vs [I].

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.

Effects of Some Antibiotics on Human Erythrocyte 6-Phosphogluconate Dehydrogenase: Anin vitroandin vivoStudy

The in vitro and in vivo effects of some antibiotics on human erythrocyte 6-phosphogluconate dehydrogenase were investigated. Human erythrocyte 6-phosphogluconate dehydrogenase was purified with ammonium sulphate precipitation, 2',5' ADP-Sepharose 4B affinity and gel filtration chromatography. Some antibiotics (netilmicin sulphate, cefepime, amikacin, isepamycin, chloramphenicol, ceftazidim, teicoplanin, ampicillin, ofloxacin, levofloxacin, cefotaxime, penicillin G, gentamicin sulphate, ciprofloxacin) inhibited enzyme activity in vitro but others (cefozin, decefin, streptomycin, combisid, and meronem) were devoid of inhibitory effects. For the drugs having low IC50 values (netilmicin sulphate and cefepime), in vivo studies were performed in rats. Netilmicin sulphate at 15-mg/kg inhibited enzyme activity significantly (p < 0.001) 1 h, 2 h, and 3 h after dosing and cefepime at 200-mg/kg very significantly (p < 0.001) inhibited the enzyme 1 h and 2 h after dosing. Netilmicin sulphate and cefepime inhibited rat erythrocyte 6-phosphogluconate dehydrogenase both in vivo and in-vitro.

In vitroeffects of some drugs on human red blood cell glucose-6-phosphate dehydrogenase enzyme activity

In vitro effects of omeprazole, morphine sulphate, remifentanyl, ketamine and vankomycin were investigated on human red blood cell glucose-6 phosphate dehydrogenase (G-6PD) (E.C. 1.1.1.49) enzyme activity purified from human red blood cell by 2', 5'ADP-Sepharose 4B affinity gel. The obtained I50 values of omeprazole, morphine, remifentanil, ketamine and vankomycin were 3.24, 43.58, 97.6, 64.16 and 0.903 mM, respectively and the Ki constants for omeprazole, morphine and vankomycin were 8.22 +/- 2.055, 25.93 +/- 6.482, and 2.71 +/- 0.677 mM, respectively and they were non competitive inhibitors.

Evaluation of effect of some corticosteroids on glucose-6-phosphate dehydrogenase and comparative study of antioxidant enzyme activities

Corticosteroids are anti-inflammatory drugs that are similar to the natural corticosteroid hormones produced by the cortex of the adrenal glands. The objective of this study was to scrutinize effects of some corticosteroids on glucose-6-phosphate dehydrogenase (G6PD) and some antioxidant enzymes. Initially, G6PD was purified from human erythrocytes by using ammonium sulphate precipitation and affinity chromatography. The two drugs, dexamethasone phosphate and prednisolone, investigated on the purified enzyme inhibited the enzyme activity. Comparative in vivo studies were performed to determine the effects of dexamethasone phosphate on the antioxidant enzyme activities using Spraque-Dawley rats. G6PD and catalase (CAT) activities were found significantly lower than in the control, whereas glutathione peroxidase (GP) activity was significantly increased in the erythrocytes of rats the receiving drug; glutathione reductase (GR) activity was unaffected. The results imply that dexamethasone phosphate may affect oxidative stress by changing antioxidant enzyme activities.

Purification and characterization of glucose 6-phosphate dehydrogenase from Lake Van fish (Chalcalburnus tarichii pallas, 1811) liver

Glucose 6-phosphate dehydrogenase (D-glucose 6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49; G6PD) was purified from Lake Van fish (Chalcalburnus tarichii pallas, 1811) liver, using a simple and rapid method, and some characteristics of the enzyme were investigated. The purification procedure was composed of two steps: homogenate preparation and 2', 5'-ADP Sepharose 4B affinity gel chromatography, which took 7-8 hours. Thanks to the two consecutive procedures, the enzyme, having specific activity of 38 EU/mg protein, was purified with a yield of 44.39% and 1310 fold. In order to control the enzyme purification SDS polyacrylamide gel electrophoresis (SDS-PAGE) was done. SDS polyacrylamide gel electrophoresis showed a single band for enzyme. Optimal pH, stable pH, optimal temperature, Km and, Vmax values for NADP+ and glucose 6-phosphate (G6P) were also determined for the enzyme. In addition, molecular weight and subunit molecular weights were found by sodium dodecyl sulfate polyacrilamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography respectively.

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.

In vivo and in vitro effects of some plant hormones on rat erythrocyte carbonic anhydrase and glucose-6-phosphate dehydrogenase activities

The present study was undertaken to determine in vivo and in vitro effects of some plant growth regulators on rat erythrocyte carbonic anhydrase (CA) and glucose-6-phosphate dehydrogenase (G6PD) activities. Both in vivo and in vitro, spermidine and kinetin did not affect enzymatic activities of CA and G6PD, whereas putrescine decreased these activities, and abscisic acid increased them. Since plants use such growth regulators, their effects should be considered on mammals consuming them since they may possess important biological effects.

Purification and investigation of some kinetic properties of glucose-6-phosphate dehydrogenase from parsley (Petroselinum hortense) leaves

In this study, glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49; G6PD) was purified from parsley (Petroselinum hortense) leaves, and analysis of the kinetic behavior and some properties of the enzyme were investigated. The purification consisted of three steps: preparation of homogenate, ammonium sulfate fractionation, and DEAE-Sephadex A50 ion exchange chromatography. The enzyme was obtained with a yield of 8.79% and had a specific activity of 2.146 U (mg protein)(-1). The overall purification was about 58-fold. Temperature of +4 degrees C was maintained during the purification process. Enzyme activity was spectrophotometrically measured according to the Beutler method, at 340 nm. In order to control the purification of enzyme, SDS-polyacrylamide gel electrophoresis was carried out in 4% and 10% acrylamide for stacking and running gel, respectively. SDS-polyacrylamide gel electrophoresis showed a single band for enzyme. The molecular weight was found to be 77.6 kDa by Sephadex G-150 gel filtration chromatography. A protein band corresponding to a molecular weight of 79.3 kDa was obtained on SDS-polyacrylamide gel electrophoresis. For the enzymes, the stable pH, optimum pH, and optimum temperature were found to be 6.0, 8.0, and 60 degrees C, respectively. Moreover, KM and Vmax values for NADP+ and G6-P at optimum pH and 25 degrees C were determined by means of Lineweaver-Burk graphs. Additionally, effects of streptomycin sulfate and tetracycline antibiotics were investigated for the enzyme activity of glucose-6-phosphate dehydrogenase in vitro.

Effects of melatonin on enzyme activities of glucose-6-phosphate dehydrogenase from human erythrocytes in vitro and from rat erythrocytes in vivo

The in vivo and in vitro effects of melatonin on glucose-6-phosphate dehydrogenase (G6PD) from human erythrocytes have been investigated. For this purpose, human erythrocyte glucose-6-phosphate dehydrogenase was purified, at the beginning, 13.654 times in a yield of 28% by using ammonium sulphate precipitation and 2',5'-ADP Sepharose 4B affinity gel. A temperature of +4 degrees C was maintained during the purification process. Enzyme activity was determined by the Beutler method using a spectrophotometer at 340 nm. This method was utilized for all kinetic studies. For in vitro experiments, the enzyme activity increased below 0.08 mM melatonin concentration and reached a plateau above 0.1 mM. Ten mg kg(-1)melatonin was administered intraperitonally and indicated the stimulatory effect on the enzyme. Time-dependent in vivo studies were executed for melatonin in Sprague-Dawley type rats. It was found that G6PD activity in the erythrocytes was increased by the melatonin in 1.5 and 3.5 h. These results show that both in vitro(below 0.08 mM) and in vivo pharmacological levels of melatonin increased enzyme activity in erythrocytes. The findings also indicate that melatonin may be pharmacologically useful in patients where a deficiency of the enzyme in red blood cells (RBC) causes haemolytic anaemia.

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 x 10(-3) M for metamizol and 1.32 x 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.

EFFECTS OF SOME ANTIBIOTICS ON ENZYME ACTIVITY OF GLUCOSE-6-PHOSPHATE DEHYDROGENASE FROM HUMAN ERYTHROCYTES

Inhibitory effects of some antibiotics on glucose-6-phosphate dehydrogenase from the erythrocytes of human have been investigated. For this purpose, at the beginning, erythrocyte glucose-6-phosphate dehydrogenase was purified 13.654 times in a yield of 28% by using ammonium sulphate precipitation and 2',5'-ADP Sepharose 4B affinity gel. Temperature of +4 degrees C was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340 nm. This method was utilized for all kinetic studies. Sodium ceftizoxime, sodium ampicillin, sodium cefuroxime, sodium cefazolin, sodium cefoperazone, streptomycin sulphate, gentamicin sulphate, and netilmicin sulphate were used as antibiotics. All the antibiotics indicated the inhibitory effects on the enzyme. K(i)constants for glucose-6-phosphate dehydrogenase were found by means of Lineweaver-Burk graphs. While sodium cefoperazone, gentamicin sulphate, and netilmicin sulphate showed competitive inhibition, the others displayed non-competitive inhibition. In addition, I(50)values of the antibiotics were determined by plotting activity percent vs [I]. In addition, in vivo studies were done for sodium sefuroxime in Sprague-Dawley type rats. It was found that G6PD in erythrocyte was more inhibited by the drug in 2.5 h. 2000 Academic Press@p$hr Copyright 2000 Academic Press.

Human glucose-6-phosphate dehydrogenase: primary structure and cDNA cloning

The X-chromosome-linked glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ oxidoreductase, EC 1.1.1.49) of humans and other mammals consists of a subunit with a molecular weight of about 58,000. The enzyme plays a key role in the generation of NADPH, particularly in matured erythrocytes, and the genetic deficiency of the enzyme is associated with chronic and drug- or food-induced hemolytic anemia in humans. The enzyme was purified to homogeneity from human erythrocytes. The complete amino acid sequence of the subunit, consisting of 531 amino acid residues, was determined by automated and manual Edman degradation of tryptic, chymotryptic, thermolytic, and cyanogen bromide peptides obtained from the enzyme. Based on the amino acid sequence data thus obtained, a 41-mer oligonucleotide with unique sequence was prepared. Two cDNA libraries constructed in phage lambda gt11--i.e., a human liver cDNA library and a human hepatoma Li-7 cDNA library--were screened with the synthetic nucleotide probe. Two positive clones, lambda G6PD-19 and lambda G6PD-25, were obtained from the hepatoma library. lambda G6PD-19 contained an insertion of 2.0 kilobase pairs (kbp), and encoded 204 amino acid residues that were completely compatible with the COOH-terminal portion of the enzyme. The insertion of the clone had a 3' noncoding region of 1.36 kbp. The other clone, lambda G6PD-25, had an insertion of 1.8 kbp and encoded 362 amino acid residues of G6PD. Southern blot analysis of DNA samples obtained from cells with and without the human X chromosome indicated that the cDNA hybridizes with a sequence in the X chromosome.

Isolation of human glucose-6-phosphate dehydrogenase (G6PD) cDNA clones: primary structure of the protein and unusual 5' non-coding region

Glucose-6-phosphate dehydrogenase (G6PD) is an ubiquitous enzyme which by determining the NADPH level has a crucial role in NADPH-mediated reductive processes in all cells (1). The structural gene for G6PD, Gd, is X-linked in mammals and on the basis of its expression in many tissues, it can be regarded as a typical "housekeeping" gene (2). Over 300 variants of the protein are known, many of which have deficient enzyme activity. Nearly 100 of these variants are polymorphic in various populations (3). The mammalian enzyme is a homodimer or a homotetramer with a subunit molecular weight of approximately 56000 daltons (4). Here we report the isolation of cDNA clones from HeLa cells, SV40-transformed human fibroblasts, human placenta and human teratocarcinoma cell lines. These clones have enabled us to sequence the entire coding region of Gd. Thus, the entire amino acid sequence of human G6PD is provided for the first time. This work is the first step for structural analysis of G6PD variants and for an understanding of the biological features of this enzyme at the molecular level.

Glucose-6-phosphate dehydrogenase. A transferred nuclear Overhauser enhancement study of NADP+ conformations in enzyme-coenzyme binary complexes

The conformation of NADP+ in glucose-6-phosphate-dehydrogenase--NADP+ binary complexes has been investigated using proton-proton transferred nuclear Overhauser enhancement measurements to determine interproton distance ratios between bound NADP+ protons. The enzymes from Saccharomyces cerevisiae (brewer's yeast and baker's yeast) and Hansenula jadinii (Candida utilis, Torula utilis) form binary complexes with NADP+ in which the glycosidic bond of the adenine moiety is in the anti conformation whereas that of the nicotinamide moiety exists as a syn (69-70%)/anti (30-40%) mixture. The enzymes have similar subunit sizes (Mr approximately 58 000) and it is shown that they bind NADP+ in essentially similar conformations. Inactivation of the baker's yeast enzyme with acetylsalicylic acid caused little if any alteration in the conformation of bound NADP+, and the presence of NADP+ during inactivation afforded very little protection to the enzyme. Inactivation rates were, however, lower in the presence of glucose 6-phosphate. It is concluded that the epsilon-amino group of the lysine residue that is acetylated during the inactivation reaction with acetylsalicylic acid is not necessary for binary complex formation between the enzyme and NADP+, but that it is situated in a part of the molecule affected by formation of the enzyme--glucose-6-phosphate complex. The implication of the findings for the catalytic process, and related evolutionary aspects, are discussed briefly.

Glucose-6-phosphate dehydrogenase from rabbit erythrocytes

Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) was purified from rabbit erythrocytes. Initial velocity studies and product and and dead-end inhibitor studies with this enzyme are consistent with a rapid equilibrium random mechanism with an enzyme-NADPH-glucose 6-phosphate dead-end complex.