Age-associated tyrosine nitration of rat skeletal muscle glycogen phosphorylase b: characterization by HPLC-nanoelectrospray-Tandem mass spectrometry.
We identified age-dependent post-translational modifications of skeletal muscle glycogen phosphorylase b (Ph-b), isolated from F1 hybrids of Fisher 344xBrown Norway rats. Ph-b isolated from 34 months old rats showed a statistically significant decrease in specific activity compared to 6 months old animals: 13.8+/-0.7 vs. 20.6+/-0.8Umg(-1) protein, respectively. Western blot analysis of the purified Ph-b with anti-3-NT antibodies revealed an age-dependent accumulation of 3-nitrotyrosine (3-NT), quantified by reverse-phase HPLC-UV analysis to increase from 0.05+/-0.03 to 0.34+/-0.11 ( mol 3-NT/ mol Ph-b) for 6 vs. 34 months old rats, respectively. HPLC-nanoelectrospray ionization-tandem mass spectrometry revealed the accumulation of 3-NT on Tyr(113), Tyr(161) and Tyr(573). While nitration of Tyr(113) was detected for both young and old rats, 3-NT at positions 161 and 573 was identified only for Ph-b isolated from 34 months old rats. The sequence of the rat muscle Ph-b was corrected based on our protein sequence mapping and a custom rat PHS2 sequence containing 17 differently located amino acid residues was used instead of the database sequence. The in vitro reaction of peroxynitrite with Ph-b resulted in the nitration of multiple Tyr residues at positions 51, 52, 113, 155, 185, 203, 262, 280, 404, 473, 731, and 732. Thus, the in vitro nitration conditions only mimic the nitration of a single Tyr residue observed in vivo suggesting alternative pathways controlling the accumulation of 3-NT in vivo. Our data show a correlation of age-dependent 3-NT accumulation with Ph-b inactivation.[1]References
- Age-associated tyrosine nitration of rat skeletal muscle glycogen phosphorylase b: characterization by HPLC-nanoelectrospray-Tandem mass spectrometry. Sharov, V.S., Galeva, N.A., Kanski, J., Williams, T.D., Schöneich, C. Exp. Gerontol. (2006) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg