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Title: Identification and characterization of a selenium-dependent glutathione peroxidase in Setaria cervi

Abstract

Setaria cervi a bovine filarial parasite secretes selenium glutathione peroxidase during in vitro cultivation. A significant amount of enzyme activity was detected in the somatic extract of different developmental stages of the parasite. Among different stages, microfilariae showed a higher level of selenium glutathione peroxidase activity followed by males then females. However, when the activity was compared in excretory secretory products of these stages males showed higher activity than microfilariae and female worms. The enzyme was purified from female somatic extract using a combination of glutathione agarose and gel filtration chromatography, which migrated as a single band of molecular mass {approx}20 kDa. Selenium content of purified enzyme was estimated by atomic absorption spectroscopy and found to be 3.5 ng selenium/{mu}g of protein. Further, inhibition of enzyme activity by potassium cyanide suggested the presence of selenium at the active site of enzyme. This is the first report of identification of selenium glutathione peroxidase from any filarial parasite.

Authors:
 [1];  [2]
  1. Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, UP (India)
  2. Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, UP (India). E-mail: sushmarathaur@yahoo.com
Publication Date:
OSTI Identifier:
20710801
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 331; Journal Issue: 4; Other Information: DOI: 10.1016/j.bbrc.2005.03.235; PII: S0006-291X(05)00743-6; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ABSORPTION SPECTROSCOPY; CATTLE; CHROMATOGRAPHY; CYANIDES; ENZYME ACTIVITY; GLUTATHIONE; IN VITRO; PARASITES; PEROXIDASES; POTASSIUM; SELENIUM

Citation Formats

Singh, Anchal, and Rathaur, Sushma. Identification and characterization of a selenium-dependent glutathione peroxidase in Setaria cervi. United States: N. p., 2005. Web. doi:10.1016/j.bbrc.2005.03.235.
Singh, Anchal, & Rathaur, Sushma. Identification and characterization of a selenium-dependent glutathione peroxidase in Setaria cervi. United States. doi:10.1016/j.bbrc.2005.03.235.
Singh, Anchal, and Rathaur, Sushma. Fri . "Identification and characterization of a selenium-dependent glutathione peroxidase in Setaria cervi". United States. doi:10.1016/j.bbrc.2005.03.235.
@article{osti_20710801,
title = {Identification and characterization of a selenium-dependent glutathione peroxidase in Setaria cervi},
author = {Singh, Anchal and Rathaur, Sushma},
abstractNote = {Setaria cervi a bovine filarial parasite secretes selenium glutathione peroxidase during in vitro cultivation. A significant amount of enzyme activity was detected in the somatic extract of different developmental stages of the parasite. Among different stages, microfilariae showed a higher level of selenium glutathione peroxidase activity followed by males then females. However, when the activity was compared in excretory secretory products of these stages males showed higher activity than microfilariae and female worms. The enzyme was purified from female somatic extract using a combination of glutathione agarose and gel filtration chromatography, which migrated as a single band of molecular mass {approx}20 kDa. Selenium content of purified enzyme was estimated by atomic absorption spectroscopy and found to be 3.5 ng selenium/{mu}g of protein. Further, inhibition of enzyme activity by potassium cyanide suggested the presence of selenium at the active site of enzyme. This is the first report of identification of selenium glutathione peroxidase from any filarial parasite.},
doi = {10.1016/j.bbrc.2005.03.235},
journal = {Biochemical and Biophysical Research Communications},
number = 4,
volume = 331,
place = {United States},
year = {Fri Jun 17 00:00:00 EDT 2005},
month = {Fri Jun 17 00:00:00 EDT 2005}
}
  • Recent advances in quantitative methods and sensitive imaging techniques of trace elements provide opportunities to uncover and explain their biological roles. In particular, the distribution of selenium in tissues and cells under both physiological and pathological conditions remains unknown. In this work, we applied high-resolution synchrotron X-ray fluorescence microscopy (XFM) to map selenium distribution in mouse liver and kidney. Liver showed a uniform selenium distribution that was dependent on selenocysteine tRNA{sup [Ser]Sec} and dietary selenium. In contrast, kidney selenium had both uniformly distributed and highly localized components, the latter visualized as thin circular structures surrounding proximal tubules. Other parts ofmore » the kidney, such as glomeruli and distal tubules, only manifested the uniformly distributed selenium pattern that co-localized with sulfur. We found that proximal tubule selenium localized to the basement membrane. It was preserved in Selenoprotein P knockout mice, but was completely eliminated in glutathione peroxidase 3 (GPx3) knockout mice, indicating that this selenium represented GPx3. We further imaged kidneys of another model organism, the naked mole rat, which showed a diminished uniformly distributed selenium pool, but preserved the circular proximal tubule signal. We applied XFM to image selenium in mammalian tissues and identified a highly localized pool of this trace element at the basement membrane of kidneys that was associated with GPx3. XFM allowed us to define and explain the tissue topography of selenium in mammalian kidneys at submicron resolution.« less
  • Selenium concentrations in blood, urine, hair, and tap water were determined in samples obtained from individuals exposed to varying amounts of the element via water from home wells. Glutathione peroxidase activities were also determined on the blood samples. Correlations of blood Se with the enzyme activity were not statistically significant. Correlations of water Se, urine Se, and hair Se with glutathione peroxidase activity were also not statistically significant. It is concluded that a relationship between Se and glutathione peroxidase activity does not exist when Se status is adequate.
  • The relationship of whole blood selenium (Se) to glutathione peroxidase (GPX) activity was examined for individuals in New Zealand, Oregon, and South Dakota who represented, respectively, populations with exposure to low, medium, and high amounts of Se. The mean (respective) blood Se levels were 60, 200, and 400 ng/ml. Intergroup differences in blood Se levels were highly significant. GPX assays were performed using two variations of an enzyme-coupled procedure to assess the equivalence of the two methods. Despite a fourfold difference in absolute activities measured by these methods, the GPX activities were highly correlated between procedures. Average blood GPX activitymore » was significantly lower for the New Zealand group compared with the other two groups, but there was no difference in GPX activities between the Oregon and South Dakota groups. Linear regression of GPX vs. Se values within each group indicated a significant correlation of these parameters only in the New Zealand group. Comparison of these parameters for combined data from all three groups also showed a significant positive correlation. A saturation model (ln GPX = k{sub 1} + k{sub 2} (Se){sup {minus}1}) fits the combined data better than does direct comparison of the two parameters. These results suggest that GPX activity is an appropriate indicator of human Se status only in populations with below normal exposure to Se, as activity of this enzyme is saturated at relatively low levels.« less
  • Concentration of selenium in whole blood and plasma, lipid peroxides in plasma, and glutathione peroxidase activities in red blood cell hemolysates and plasma were determined in 49 coal power plant workers and in 50 rubber factory workers. The results were compared with those obtained for 58 nonindustrial controls. Whole blood selenium was significantly lower and plasma lipid peroxides were significantly higher in power plant workers when compared to the nonindustrial group. In the rubber factory workers, whole blood selenium and red blood cells and plasma glutathione peroxidase activities were significantly lower than in the control group. Urinary output of seleniummore » was also significantly decreased in rubber factory workers. Slightly elevated lipid peroxides were also observed in that group. It seems reasonable to conclude that the lower blood selenium and decreased urinary output of this element may result from increased loss of selenium with perspiration. No correlation has been observed between selenium concentration and glutathione peroxidase activity and between enzyme activity and lipid peroxides concentration in the industrial group.« less
  • Studies were conducted in an attempt to define a biochemical index of selenium toxicity rather than weight loss, liver disease and death. Rats, maintained on selenium deficient diets, received in drinking water various levels of selenium as Na/sub 2/SeO/sub 3/(0.1, 1.0, 1.5, 2.0 ppM). Changes in selenium dependent glutathione peroxidase (GSH-Px) activities and specific activities (nCi/sup 75/ Se/..mu..g Se) were determined in liver, kidney and plasma at baseline and two and ten weeks after repletion. In initial selenium deficient rats, GSH-Px activities were markedly depressed and specific activities elevated as compared to 0.1 ppM controls. After two weeks, liver andmore » plasma GSH-Px activities increased, and plasma, liver and kidney specific activities decreased in a concentration dependent manner. In kidney, there were no differences in enzyme activity at either two or ten weeks. At ten weeks, liver GSH-Px activities continued to increase in the 1.0 ppM group, but were depressed at both the 1.5 and 2.0 ppM levels. Specific activities were also depressed in liver and excretion was not increased at these levels. This suggests a biochemical toxicity in liver at levels above 1.0 ppM after ten weeks, prior to the onset of gross pathological changes.« less