title: Oxidative modification and aggregation of creatine kinase from aged mouse skeletal muscle.
abstract: Creatine kinase catalyzes the reversible transfer of the gamma phosphate from ATP to creatine forming the high energy compound creatine phosphate. Muscle creatine kinase (CKm) activity maintains energetic homeostasis as variations in energy requirements dictate that ATP be readily available. Recent studies suggest that CKm activity is altered during aging. Proteomic analyses have shown that CKm is 3-nitrotyrosine (3-NT) modified and carbonylated in aged rodent skeletal muscle. However, it remains unknown if these modifications affect its structure and activity. To address this we characterized oxidatively modified CKm from the quadriceps of young, middle-aged, and aged mice. Our data indicate that 3-NT modified and carbonylated CKm are found predominantly in aged muscle and that it exists in high molecular weight oligomers and insoluble protein aggregates. CKm from middle-aged and aged mouse quadriceps also exhibits structural instability that may account for its reduction in function. These structural and functional changes correlate with the differential protein modifications. Interestingly, the majority of the age-related changes in enzyme activity and protein stability occurred by middle age. Our studies indicate that the age-associated oxidative and nitrative modification of CKm results in a decrease in its activity and may cause structural changes that promote oligomerization and aggregation.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-0643, USA.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Nuss
authors.forename: James K
authors.initials: JK
authors.lastname: Amaning
authors.forename: C Eric
authors.initials: CE
authors.lastname: Bailey
authors.forename: James H
authors.initials: JH
authors.lastname: DeFord
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Dimayuga
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Rabek
authors.forename: John
authors.initials: J
authors.lastname: Papaconstantinou
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism*; D024981:Glycogen Phosphorylase / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000378:metabolism*; D018384:Oxidative Stress; D050050:Protein Carbonylation / Q000502:physiology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: C002744:3-nitrotyrosine; D014443:Tyrosine; D024981:Glycogen Phosphorylase; D003402:Creatine Kinase