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Am J Physiol Endocrinol Metab. 2010 May;298(5):E978-87. doi: 10.1152/ajpendo.00739.2009. Epub 2010 Feb 16.

Nitration of specific tyrosines in FoF1 ATP synthase and activity loss in aging.

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  • 1University of California, Davis, Department of Molecular Biosciences, 1120 Haring Hall, One Shields Ave., Davis, CA 95616, USA.

Abstract

It has been reported that C-nitration of proteins occurs under nitrative/oxidative stress; however, its role in pathophysiological situations is not fully understood. In this study, we determined that nitration of Tyr(345) and Tyr(368) in the beta-subunit of the mitochondrial F(o)F(1)-ATPase is a major target for nitrative stress in rat liver under in vivo conditions. The chemical characteristics of these Tyr make them suitable for a facilitated nitration (solvent accessibility, consensus sequence, and pK(a)). Moreover, beta-subunit nitration increased significantly with the age of the rats (from 4 to 80 weeks old) and correlated with decreased ATP hydrolysis and synthesis rates. Although its affinity for ATP binding was unchanged, maximal ATPase activity decreased between young and old rats by a factor of two. These changes directly impacted the available ATP concentration in vivo, and it was expected that they would affect multiple cellular ATP-dependent processes. For instance, at least 50% of available [ATP] in the liver of older rats would have to be committed to sustain maximal Na(+)-K(+)-ATPase activity, whereas only 30% would be required for young rats. If this requirement was not fulfilled, the osmoregulation and Na(+)-nutrient cotransport in liver of older rats would be compromised. On the basis of our studies, we propose that targeted nitration of the beta-subunit is an early marker for nitrative stress and aging.

PMID:
20159857
[PubMed - indexed for MEDLINE]
PMCID:
PMC2867368
Free PMC Article

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