title: Peroxynitrite-mediated oxidative modifications of myosin and implications on structure and function.
abstract: Abstract The peroxynitrite-induced functional impairment of myosin was studied in different reaction conditions, known to alter the oxidative chemistry of peroxynitrite, to better understand the molecular mechanisms of this interaction. It is shown that peroxynitrite is able to enhance the basal MgATPase activity up to 2-fold while inhibiting the actin-stimulated ATPase activity of myosin and that the extent of these functional alterations is dependent on the reaction medium. The observed changes in the stimulation of the MgATPase activity correlate with the extent of carbonyl formation in myosin. The enzyme inhibition is more potent in conditions where the efficiency of tyrosine nitration and peroxynitrite reactivity towards sulphydryls are lower. Together with the observation that reversion of sulphydryl oxidation did not lead to the recovery of myosin functional and structural impairments, these results point out to the importance of protein carbonylation as a post-translational modification in the peroxynitrite-induced myosin functional impairment.
authors.affiliation: Depto Bioquímica y Biología Molecular, Facultad de Ciencias, University of Extremadura, 06071 Badajoz, Spain. ttiago@ualg.pt
authors.forename: Teresa
authors.initials: T
authors.lastname: Tiago
authors.forename: Pedro S
authors.initials: PS
authors.lastname: Palma
authors.forename: Carlos
authors.initials: C
authors.lastname: Gutierrez-Merino
authors.forename: Manuel
authors.initials: M
authors.lastname: Aureliano
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D009218:Myosins / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011817:Rabbits
chemical_list: D030421:Peroxynitrous Acid; D009218:Myosins