Methods for purification of glutathione peroxidase and related enzymes

Purification of glutathione S-transferase enzyme from liver tissue of shabout (Barbus grypus Heckel) and investigation of the inhibition effect of some metal ions under in vitro conditions

Shabout is a fish with high nutritional value and economic potential. This fish is exposed to environmental factors due to the metal toxicity in its habitat and, consequently, its diet. The main purpose of this study was to determine how the detoxification mechanism of shabout is affected by examining the interaction of glutathione s-transferase enzyme with heavy metals. In our study, elemental analysis was first performed with the ICP-OES on water samples taken from three different points to detect metal toxicity in the habitat of the shabout. Then, the GST enzyme from the liver tissue of the shabout was purified for the first time by our team using the glutathione agarose affinity chromatography technique. Finally, the inhibition effects of nitrate salts of some metal ions on the purified enzyme activity were investigated under in vitro conditions. It was determined that the water courses where the fish were sampled in our study were alarming in terms of heavy metal content. While shabout liver showed Fe3+ activation effect on GST enzyme under in vitro conditions, metal ions Na+, Zn2+, Co2+, Cu2+ and Pb2+ showed inhibition effects. The detected inhibition concentration range showed that the enzyme is quite resistant to the metal salts whose effects were examined. It was concluded that in the consumption of shabout, emphasized to be a nutritious fish, the heavy metal levels of the region where the fish is caught should be taken into account and catching should be made in water resources inspected by relevant experts.

Purification and characterisation of glutathione reductase from scorpionfish (scorpaena porcus) and investigation of heavy metal ions inhibition

In the current study, glutathione reductase was purified from Scorpion fish (Scorpaena porcus) liver tissue and the effects of heavy metal ions on the enzyme activity were determined. The purification process consisted of three stages; preparation of the homogenate, ammonium sulphate precipitation and affinity chromatography purification. At the end of these steps, the enzyme was purified 25.9-fold with a specific activity of 10.479 EU/mg and a yield of 28.3%. The optimum pH was found to be 6.5, optimum substrate concentration was 2 mM NADPH and optimum buffer was 300 mM KH₂PO_4. After purification, inhibition effects of Mn⁺², Cd⁺², Ni⁺², and Cr³⁺, as heavy metal ions were investigated. IC₅₀ values of the heavy metals were calculated as 2.4 µM, 30 µM, 135 µM and 206 µM, respectively.

PEGylation and antioxidant effects of a human glutathione peroxidase 1 mutant

Human glutathione peroxidase1 (hGPx1) is a good antioxidant and potential drug, but the limited availability and poor stability of hGPx1 have affected its development and application. To solve this problem, we prepared a hGPx1 mutant (GPx1M) with high activity in an Escherichia coli BL21(DE3)cys auxotrophic strain using a single protein production (SPP) system. In this study, the GPx1M was conjugated with methoxypolyethylene glycol-succinimidyl succinate (SS-mPEG, M_w = 5 kDa) chains to enhance its stability. SS-mPEG-GPx1M and GPx1M exhibited similar enzymatic activity and stability toward pH and temperature change, and in a few cases, SS-mPEG-GPx1M was discovered to widen the range of pH stability and increase the temperature stability. Lys 38 was confirmed as PEGylated site by liquid-mass spectrometry. H9c2 cardiomyoblast cells and Sprague-Dawley (SD) rats were used to evaluate the effects of GPx1M and SS-mPEG-GPx1M on preventing or alleviating adriamycin (ADR)-mediated cardiotoxicity, respectively. The results indicated that GPx1M and SS-mPEG-GPx1M had good antioxidant effects in vitro and in vivo, and the effect of SS-mPEG-GPx1M is more prominent than GPx1M in vivo. Thus, PEGylation might be a promising method for the application of GPx1M as an important antioxidant and potential drug.

Fruit Quality Characterization of New Sweet Cherry Cultivars as a Good Source of Bioactive Phenolic Compounds with Antioxidant and Neuroprotective Potential

Sweet cherries (Prunus avium L.) are highly appreciated fruits for their taste, color, nutritional value, and beneficial health effects. In this work, seven new cultivars of sweet cherry were investigated for their main quality traits and nutraceutical value. The phytochemical profile of three classes of phenolic compounds and the antioxidant activity of the new cultivars were investigated through high-performance liquid chromatography with diode array detection (HPLC-DAD) and spectrophotometric assays, respectively, and compared with those of commonly commercialized cultivars. Cyanidine-3-O-rutinoside was the main anthocyanin in all genotypes, and its levels in some new cultivars were about three-fold higher than in commercial ones. The ORAC-assayed antioxidant capacity was positively correlated with the total anthocyanin index. The nutraceutical value of the new cultivars was investigated in terms of antioxidant/neuroprotective capacity in neuron-like SH-SY5Y cells. Results demonstrated that the new cultivars were more effective in counteracting oxidative stress and were also able to upregulate brain-derived neurotrophic factor (BDNF), a pro-survival neurotrophin, suggesting their potential pleiotropic role in counteracting neurodegenerations.

The Evaluation of Glutathione Reductase and Malondialdehyde Levels in Patients With Lumbar Disc Degeneration Disease

BACKGROUND/AIM

Increased oxidative stress plays a crucial role in pathogenesis of various diseases. The present study aims to investigate glutathione reductase (GR) and malondialdehyde (MDA) enzymes as markers of oxidative stress mechanisms in lumbar disc degeneration disease (LDDD).

PATIENTS AND METHODS

The study group consisted of 39 patients diagnosed with LDD and 37 healthy individuals in the control group. The enzyme-linked immunosorbent assay (ELISA) method was used to determine serum GR and MDA levels in the two study groups.

RESULTS

Serum GR levels were significantly lower (p=0.008), while MDA levels were significantly higher in the patient group compared to the controls (p=0.025).

CONCLUSION

Oxidative stress mechanisms play a crucial role in disc degeneration and GR deficiency could be an eligible risk factor for LDDD.

Characterization and Purification of Glutathione S-Transferase from the Liver and Gill Tissues of Ağrı Balık Lake Trout Salmo trutta labrax and the Effects of Heavy Metal Ions on Its Activity

Glutathione S-transferase (GST) from the liver and gill tissues of Ağrı Balık Lake Trout (also known as Black Sea Trout) Salmo trutta labrax was characterized and purified, and the toxic effects of some heavy metal ions on the enzyme's activity were analyzed. Liver GST was purified 930 times, resulting in 56% yield using glutathione-agarose affinity chromatography and a specific activity of 60.87 endotoxin units (EU)/mg protein. Using the same procedure, gill GST was purified 576 times, resulting in a 60% yield and specific activity of 46.8 EU/mg protein. The purity check of the purified enzymes was determined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Optimal pH, ionic strength, and stable pH were found for each tissue, and separate KM and Vmax values were determined for reduced glutathione and 2,4-dinitrochlorobenzene substrates. Heavy metal ions that have toxic effects on living organisms and are known to contribute to environmental pollution were selected, and their in vitro effects on enzyme activity were analyzed. The IC50 values and Ki constants of those metal ions showing an inhibitory effect on GST activity were determined.

Interaction of the transactivation domain of B-Myb with the TAZ2 domain of the coactivator p300: molecular features and properties of the complex

The transcription factor B-Myb is a key regulator of the cell cycle in vertebrates, with activation of transcription involving the recognition of specific DNA target sites and the recruitment of functional partner proteins, including the coactivators p300 and CBP. Here we report the results of detailed studies of the interaction between the transactivation domain of B-Myb (B-Myb TAD) and the TAZ2 domain of p300. The B-Myb TAD was characterized using circular dichroism, fluorescence and NMR spectroscopy, which revealed that the isolated domain exists as a random coil polypeptide. Pull-down and spectroscopic experiments clearly showed that the B-Myb TAD binds to p300 TAZ2 to form a moderately tight (K(d) ~1.0-10 µM) complex, which results in at least partial folding of the B-Myb TAD. Significant changes in NMR spectra of p300 TAZ2 suggest that the B-Myb TAD binds to a relatively large patch on the surface of the domain (~1200 Å(2)). The apparent B-Myb TAD binding site on p300 TAZ2 shows striking similarity to the surface of CBP TAZ2 involved in binding to the transactivation domain of the transcription factor signal transducer and activator of transcription 1 (STAT1), which suggests that the structure of the B-Myb TAD-p300 TAZ2 complex may share many features with that reported for STAT1 TAD-p300 TAZ2.

Purification and properties of glutathione reductase from liver of the anoxia-tolerant turtle, Trachemys scripta elegans

Glutathione reductase (GR) is a homodimeric flavoprotein that catalyzes the reduction of oxidized glutathione (GSSG) using NADPH as a cofactor. The enzyme is a major component of cellular defense mechanisms against oxidative injury. In this study, GR was purified from the liver of the anoxia-tolerant turtle, Trachemys scripta elegans. The overall fold purifications were 13.3- and 12.1-fold with final specific activities of 5.5 and 1.44 U/mg of protein for control and anoxic turtle GR, respectively. SDS-PAGE of purified turtle liver GR showed a single protein band at approximately 55 kDa. Reverse phase HPLC of turtle GR revealed a single peak that had the same retention time as yeast GR. No new isoform of GR was detected in liver of T. s. elegans during anoxia. The K (m) values of turtle GR for GSSG and NADPH was 44.6 and 6.82 microM, respectively, suggesting a substantially higher affinity of turtle GR toward GSSG than most other vertebrates. Unlike other human GR, NADP(+ )did not inhibit turtle GR activity. The activation energy of turtle GR, calculated from the slope of the Arrhenius plot, was 32.2 +/- 2.64 kJ/mol. Turtle GR had high activity under a broad pH range (having activity between pHs 4 and 10; optimal activity at pH 6.5) and the enzyme maintains activity under the pH drop that occurs under anoxic conditions. The high affinity of turtle GR suggests that turtles have high redox buffering capacity of tissues to protect against oxidative stress encountered during anoxia/reoxygenation.

Direct chemiluminescent imaging detection of Cu/Zn-superoxidase dismutase, glutathione peroxidase, carbonic anhydrase-III, and catalase in rat liver cytosol separated by native porous gradient polyacrylamide gel electrophoresis

The cytosolic enzymes extracted from rat hepatocytes were separated by native porous gradient-PAGE (PG-PAGE) and were detected with a sensitive and fast chemiluminescence (CL) imaging method. Several peroxidases including glutathione peroxidase, Cu/Zn-superoxidase dismutase, and some other metallo-enzymes such as catalase, carbonic anhydrase-III (CA-III) present in the cytosol of rat hepatocytes have been selectively and sensitively detected by the direct CL imaging method using the luminol-H(2)O(2) chemiluminescent reagents. All detections after PG-PAGE were completed within 9 min. The linear range for the typical metallo-enzyme, e.g., CA-III is 0.75-4.9 microg/mL, with a detection limit of 0.25 microg/mL. In comparison with the traditional CBB-R250 staining method, the detection period decreased about 70 times and the detection sensitivity improved over ten times. Furthermore, two enzymes present in rat liver cytosol were identified employing MALDI-MS analysis of the tryptic digest after PG-PAGE.

Purification and characterization of glutathione reductase from bovine erythrocytes

Glutathione reductase (E.C.1.8.1.7; GR) was purified from bovine erythrocytes and some characteristics properties of the enzyme were investigated. The purification procedure was composed of preparation of the hemolysate, ammonium sulfate fractionation, affinity chromatography on 2',5'-ADP Sepharose 4B, and gel filtration chromatography on Sephadex G-200. As a result of four consecutive procedures, the enzyme was purified 31,250-fold with a yield of 11.39%. Specific activity at the final step was 62.5 U (mg proteins)(-1). For the enzyme, optimum pH, optimum temperature, optimum ionic strength, and stable pH were found to be 7.3, 55 degrees C, 435 mM, 7.3, respectively. The molecular weight of the enzyme was found to be 118 kDa by Sephadex G-200 gel filtration chromatography and the subunit molecular weight was found to be 58 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In addition, Km and Vmax values were determined for glutathione disulfide (GSSG) and NADPH. Ki constants and inhibition types were established for glutathione (GSH) and NADP+. Also, effects of NADPH and GSSG were investigated on the enzyme activities.

New family of glutathionyl-biomimetic ligands for affinity chromatography of glutathione-recognising enzymes

Three anthraquinone glutathionyl-biomimetic dye ligands, comprising as terminal biomimetic moiety glutathione analogues (glutathionesulfonic acid, S-methyl-glutathione and glutathione) were synthesised and characterised. The biomimetic ligands were immobilised on agarose gel and the affinity adsorbents, together with a nonbiomimetic adsorbent bearing Cibacron Blue 3GA, were studied for their purifying ability for the glutathione-recognising enzymes, NAD+-dependent formaldehyde dehydrogenase (FaDH) from Candida boidinii, NAD(P)+-dependent glutathione reductase from S. cerevisiae (GSHR) and recombinant maize glutathione S-transferase I (GSTI). All biomimetic adsorbents showed higher purifying ability for the target enzymes compared to the nonbiomimetic adsorbent, thus demonstrating their superior effectiveness as affinity chromatography materials. In particular, the affinity adsorbent comprising as terminal biomimetic moiety glutathionesulfonic acid (BM1), exhibited the highest purifying ability for FaDH and GSTI, whereas, the affinity adsorbent comprising as terminal biomimetic moiety methyl-glutathione (BM2) exhibited the highest purifying ability for GSHR. The BM1 adsorbent was integrated in a facile two-step purification procedure for FaDH. The purified enzyme showed a specific activity equal to 79 U/mg and a single band after sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis. Molecular modelling was employed to visualise the binding of BM1 with FaDH, indicating favourable positioning of the key structural features of the biomimetic dye. The anthraquinone moiety provides the driving force for the correct positioning of the glutathionyl-biomimetic moiety in the binding site. It is located deep in the active site cleft forming many favourable hydrophobic contacts with hydrophobic residues of the enzyme. The positioning of the glutathione-like biomimetic moiety is primarily achieved by the strong ionic interactions with the Zn2+ ion of FaDH and Arg 114, and by the hydrophobic contacts made with Tyr 92 and Met 140. Molecular models were also produced for the binding of BM1 and BM3 (glutathione-substituted) to GSTI. In both cases the biomimetic dye forms multiple hydrophobic interactions with the enzyme through binding to a surface pocket. While the glutathioine moiety of BM3 is predicted to bind in the crystallographically observed way, an alternative, more favourable mode seems to be responsible for the better purification results achieved with BM1.