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Lookup NU author(s): Professor Ruth Valentine
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Elevated plasma homocysteine is considered to be a risk factor for cardiovascular disease. The mechanisms for this effect are not fully understood but there is some evidence for a role for reactive oxygen species (ROS). This study was conducted to explore the effects of elevated plasma total homocysteine (tHcy) concentration on activity of antioxidant enzymes in the circulation. The study group consisted of 10 patients with inherited defects of homocysteine metabolism, from whom 41 blood samples were collected over a period of six months. Blood samples were also collected from 13 of their obligate heterozygous parents. For data analysis samples were classified as those with plasma tHcy < 20 μM or ≥ 20 μM. The activity of erythrocyte superoxide dismutase (SOD) and plasma glutathione peroxidase (GSHPx) was elevated in samples with plasma tHcy > 20 μM. Moreover, a significant correlation was demonstrated between plasma GSHPx activity, plasma glutathione peroxidase protein and plasma tHcy. In vitro studies confirmed that this observation was not due to a simple chemical enhancement of enzyme activity. Homocysteine protected GSHPx from loss of activity following incubation at 37°C. A similar effect was seen with another thiol-containing amino acid, cysteine. Results suggest that elevated plasma tHcy represents an oxidative stress, resulting in an adaptive increase in activity of antioxidant enzymes in the circulation.
Author(s): Moat SJ, Bonham JR, Cragg RA, Powers HJ
Publication type: Article
Publication status: Published
Journal: Free Radical Research
Year: 2000
Volume: 32
Issue: 2
Pages: 171-179
ISSN (print): 1071-5762
ISSN (electronic): 1029-2470
Publisher: Informa Healthcare
URL: http://dx.doi.org/10.1080/10715760000300171
DOI: 10.1080/10715760000300171
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