tailieunhanh - Báo cáo khoa học: Modulation of sarcoplasmic reticulum Ca2+-ATPase by chronic and acute exposure to peroxynitrite

TheCa 2+ -ATPaseof skeletalmuscle sarcoplasmic reticulum (SERCA), an integral membrane protein, becomes irre-versibly inactivatedin vitroby the addition of a single bolus of 200–300lM, and this results in a large decrease of theATP-dependentCa 2+ gradient across the sarcoplasmic reticulum (SR) membranes. The inactiva-tion of SERCA is raised by treatment of SR vesicles with repetitivemicromolar pulses of peroxynitrite. | Eur. J. Biochem. 271 2647-2657 2004 FEBS 2004 doi Modulation of sarcoplasmic reticulum Ca2 -ATPase by chronic and acute exposure to peroxynitrite Yolanda Gutierrez-Martin Francisco J. Martin-Romero Francisco A. Inesta-Vaquera Carlos Gutierrez-Merino and Fernando Henao Departamento de Bioqulmica y Biologia Molecular y Genetica Facultad de Ciencias y Escuela de Ingenierias Agrarias Universidad de Extremadura Badajoz Spain The Ca2 -ATPase of skeletal muscle sarcoplasmic reticulum SERCA an integral membrane protein becomes irreversibly inactivated in vitro by the addition of a single bolus of peroxynitrite with a of200-300 M and this results in a large decrease of the ATP-dependent Ca2 gradient across the sarcoplasmic reticulum SR membranes. The inactivation of SERCA is raised by treatment of SR vesicles with repetitive micromolar pulses of peroxynitrite. The inhibition of the SERCA is due to the oxidation of thiol groups and tyrosine nitration. Scavengers that react directly with peroxynitrite such as cysteine reduced glutathione NADH methionine ascorbate or Trolox a water-soluble analog of a-tocopherol afforded significant protection. However dimethyl sulfoxide and mannitol two hydroxyl radical scavengers and a-tocopherol did not protect SERCA from inactivation. Our results showed that the target of peroxynitrite is the cytosolic globular domain of the SERCA and that major skeletal muscle intracellular reductants ascorbate NADH and reduced glutathione protected against inhibition of this ATPase by peroxynitrite. Keywords Ca2 -ATPase calcium homeostasis peroxynitrite sarcoplasmic reticulum. The Ca2 -ATPase of sarcoplasmic reticulum SR is a membrane protein that plays a major role in skeletal muscle relaxation by sequestering cytosolic calcium within the SR in an ATP-dependent process 1 . The demonstration that oxidatively modified forms of proteins accumulate during aging as well as under pathological situations accompanied by .