title: Nitric oxide-dependent modification of the sarcoplasmic reticulum Ca-ATPase: localization of cysteine target sites.
abstract: Skeletal muscle contraction and relaxation is modulated through the reaction of sarcoplasmic reticulum (SR) protein thiols with reactive oxygen and nitrogen species. Here, we have utilized high-performance liquid chromatography-electrospray mass spectrometry and a specific thiol-labeling procedure to identify and quantify cysteine residues of the SR Ca-ATPase that are modified by exposure to nitric oxide (NO). NO and/or NO-derived species inactivate the SR Ca-ATPase and modify a broad spectrum of cysteine residues with highest reactivities towards Cys364, Cys670, and Cys471. The selectivity of NO and NO-derived species towards the SR Ca-ATPase thiols is different from that of peroxynitrite. The efficiency of NO at thiol modification is significantly higher compared with that of peroxynitrite. Hence, NO has the potential to modulate muscle contraction through chemical reaction with the SR Ca-ATPase in vivo.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66047, USA.
authors.forename: R I
authors.initials: RI
authors.lastname: Viner
authors.forename: T D
authors.initials: TD
authors.lastname: Williams
authors.forename: C
authors.initials: C
authors.lastname: Schöneich
mesh_terms: D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000032:analysis / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D013058:Mass Spectrometry; D009119:Muscle Contraction / Q000187:drug effects; D009566:Nitrates / Q000378:metabolism / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology; D010449:Peptide Mapping; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology* / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005609:Free Radicals; D009566:Nitrates; D016877:Oxidants; D013439:Sulfhydryl Reagents; C039642:peroxynitric acid; D009569:Nitric Oxide; D000252:Calcium-Transporting ATPases; D003545:Cysteine