title: Conformational change in the C-terminal domain is responsible for the initiation of creatine kinase thermal aggregation.
abstract: Protein conformational changes may be associated with particular properties such as its function, transportation, assembly, tendency to aggregate, and potential cytotoxicity. In this research, the conformational change that is responsible for the fast destabilization and aggregation of rabbit muscle creatine kinase (EC 2.7.3.2) induced by heat was studied by intrinsic fluorescence and infrared spectroscopy. A pretransitional change of the tryptophan microenvironments was found from the intrinsic fluorescence spectra. A further analysis of the infrared spectra using quantitative second-derivative and two-dimensional correlation analysis indicated that the changes of the beta-sheet structures in the C-terminal domain and the loops occurred before the formation of intermolecular cross-beta-sheet structures and the unfolding of alpha-helices. These results suggested that the pretransitional conformational changes in the active site and the C-terminal domain might result in the modification of the domain-domain interactions and the formation of an inactive dimeric form that was prone to aggregate. Our results highlighted the fact that some minor conformational changes, which were usually negligible or undetectable by normal methods, might play a crucial role in protein stability and aggregation. Our results also suggested that the changes in domain-domain interactions, but not the dissociation of the dimer, might play a crucial role in the thermal denaturation and aggregation of this dimeric two-domain protein.
authors: Department of Biological Sciences and Biotechnology, and State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China.
authors: Hua-Wei
authors: HW
authors: He
authors: Jun
authors: J
authors: Zhang
authors: Hai-Meng
authors: HM
authors: Zhou
authors: Yong-Bin
authors: YB
authors: Yan
mesh_terms: D000818:Animals; D001665:Binding Sites; D003402:Creatine Kinase / Q000032:analysis* / Q000737:chemistry* / Q000648:ultrastructure; D019281:Dimerization; D004789:Enzyme Activation; D004795:Enzyme Stability; D046912:Multiprotein Complexes / Q000032:analysis / Q000737:chemistry / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017434:Protein Structure, Tertiary; D011817:Rabbits; D013696:Temperature
chemical_list: D046912:Multiprotein Complexes; D003402:Creatine Kinase