Glutathione (GSH; gamma-L-glutamyl-L-cysteinyl-glycine), a non-protein thiol with a very low redox potential (E'0 = 240 mV for thiol-disulfide exchange), is present in high concentration up to 10 mM in yeasts and filamentous fungi. GSH is concerned with basic cellular functions as well as the maintenance of mitochondrial structure, membrane integrity, and in cell differentiation and development. GSH plays key roles in the response to several stress situations in fungi. For example, GSH is an important antioxidant molecule, which reacts non-enzymatically with a series of reactive oxygen species. In addition, the response to oxidative stress also involves GSH biosynthesis enzymes, NADPH-dependent GSH-regenerating reductase, glutathione S-transferase along with peroxide-eliminating glutathione peroxidase and glutaredoxins. Some components of the GSH-dependent antioxidative defence system confer resistance against heat shock and osmotic stress. Formation of protein-SSG mixed disulfides results in protection against desiccation-induced oxidative injuries in lichens. Intracellular GSH and GSH-derived phytochelatins hinder the progression of heavy metal-initiated cell injuries by chelating and sequestering the metal ions themselves and/or by eliminating reactive oxygen species. In fungi, GSH is mobilized to ensure cellular maintenance under sulfur or nitrogen starvation. Moreover, adaptation to carbon deprivation stress results in an increased tolerance to oxidative stress, which involves the induction of GSH-dependent elements of the antioxidant defence system. GSH-dependent detoxification processes concern the elimination of toxic endogenous metabolites, such as excess formaldehyde produced during the growth of the methylotrophic yeasts, by formaldehyde dehydrogenase and methylglyoxal, a by-product of glycolysis, by the glyoxalase pathway. Detoxification of xenobiotics, such as halogenated aromatic and alkylating agents, relies on glutathione S-transferases. In yeast, these enzymes may participate in the elimination of toxic intermediates that accumulate in stationary phase and/or act in a similar fashion as heat shock proteins. GSH S-conjugates may also form in a glutathione S-transferases-independent way, e.g. through chemical reaction between GSH and the antifugal agent Thiram. GSH-dependent detoxification of penicillin side-chain precursors was shown in Penicillium sp. GSH controls aging and autolysis in several fungal species, and possesses an anti-apoptotic feature.

Glutathione, altruistic metabolite in fungi.

One stop mycology

Realistic quantitative models require data from many laboratories. Therefore, standardization of experimental systems and assay conditions is crucial. Moreover, standards should be representative of the in vivo conditions. However, most often, enzyme-kinetic parameters are measured under assay conditions that yield the maximum activity of each enzyme. In practice, this means that the kinetic parameters of different enzymes are measured in different buffers, at different pH values, with different ionic strengths, etc. In a joint effort of the Dutch Vertical Genomics Consortium, the European Yeast Systems Biology Network and the Standards for Reporting Enzymology Data Commission, we have developed a single assay medium for determining enzyme-kinetic parameters in yeast. The medium is as close as possible to the in vivo situation for the yeast Saccharomyces cerevisiae, and at the same time is experimentally feasible. The in vivo conditions were estimated for S. cerevisiae strain CEN.PK113-7D grown in aerobic glucose-limited chemostat cultures at an extracellular pH of 5.0 and a specific growth rate of 0.1 h(-1). The cytosolic pH and concentrations of calcium, sodium, potassium, phosphorus, sulfur and magnesium were determined. On the basis of these data and literature data, we propose a defined in vivo-like medium containing 300 mM potassium, 50 mM phosphate, 245 mM glutamate, 20 mM sodium, 2 mM free magnesium and 0.5 mM calcium, at a pH of 6.8. The V(max) values of the glycolytic and fermentative enzymes of S. cerevisiae were measured in the new medium. For some enzymes, the results deviated conspicuously from those of assays done under enzyme-specific, optimal conditions.

Measuring enzyme activities under standardized in vivo-like conditions for Systems Biology

Ayurvedic herbal drugs with possible cytostatic activity

Strategies for enhancing fermentative production of glycerol—a review

Glossary of vegetable drugs in Bṛhattrayī

INTRODUCTION Glutathione S - transferase (GST) is an important enzyme in detoxification and helps in lowering oxidative stress. It is speculated that this enzyme is induced under conditions of oxidative stress as a protective mechanism. AIM To evaluate the status of Glutathione S-transferase in Coronary artery disease patients with and without type 2 Diabetes mellitus. MATERIALS AND METHODS The study was conducted in the Department of Biotechnology, Swami Satyanand College of Management and Technology in collaboration with Department of Biochemistry, Govt Medical College Amritsar. A total of 133 diagnosed cases of Coronary Artery Disease (CAD) were selected from the OPD and Medicine Ward of a private hospital, Amritsar. CAD patients were segregated into two groups i.e., group-1 and group-2 on the basis if they had Type 2 Diabetes mellitus or not. A total of 110 ages and sex matched healthy individuals were taken as controls from the general population. Written informed consent was obtained from all the subjects. All the subjects were investigated for serum GST activity, Total antioxidant status, plasma GSH levels, serum MDA and lipid profile. RESULTS Serum GST activity was significantly high (p 0.05) in plasma GSH levels were observed between CAD patients and controls. Age and sex related variations in serum GST activity were insignificant (p>0.05). CONCLUSION Increased serum GST activity in CAD patients especially with Type 2 Diabetes is suggestive of a protective mechanism to combat increased oxidative stress which was reflected by raised serum MDA level and depressed total antioxidant status in patient group. However, whether this effect is a short term or long term, a separate follow up study is required.

Role of Glutathione S-Transferase in Coronary Artery Disease Patients with and Without Type 2 Diabetes Mellitus.

The intracellular level of Na+ and K+ of S. cerevisiae strain AB1375 revealed that under KCl as well as sorbitol stress, the cationic level was comparable to the level under no stress conditions. On the other hand, there was a sharp drop in the intracellular K+ content and increase in the Na+ content on addition of NaCl to the medium. However, the total cationic level was close to that under control conditions. In addition to changes in the cationic level, an enhanced production and accumulation of glycerol were also observed under osmotic stress. A regulatory mechanism co-ordinating the intracellular concentration of glycerol as well as Na+, K+ content under osmotic stress conditions has been proposed.

Regulation of intracellular level of Na+, K+ and glycerol in Saccharomyces cerevisiae under osmotic stress.

Individual Variation in the Composition of Colostrum and Absorption of Colostral Antibodies by the Precolostral Buffalo Calf

Lipid peroxidation in Saccharomyces cerevisiae cells increased with ethanol treatment of the cells. Such cells have decreased amount of total lipid, phospholipid and free sterols. Sterol:phospholipid ratio decreased slightly in the cells treated with 4% ethanol. However, this ratio significantly increased with further rise in ethanol concentration to 12%. Relative content of glycolipids (glycolipid to phospholipid ratio) increased in ethanol-treated yeast cells. Diphosphatidylglycerol content increased significantly and phosphatidylcholine to phosphatidylethanolamine ratio decreased in ethanol-treated cells. The amount of alpha-tocopherol decreased during ethanol stress. Catalase failed to counter the effect of ethanol. The results from the present study indicated that ethanol might be interfering with the antioxidant defence mechanisms of the yeast cells.

Balwant Singh

Papers

Glossary of vegetable drugs in Bṛhattrayī

Role of Glutathione S-Transferase in Coronary Artery Disease Patients with and Without Type 2 Diabetes Mellitus.

Regulation of intracellular level of Na+, K+ and glycerol in Saccharomyces cerevisiae under osmotic stress.

Individual Variation in the Composition of Colostrum and Absorption of Colostral Antibodies by the Precolostral Buffalo Calf

Changes in the composition and peroxidation of yeast membrane lipids during ethanol stress