title: Folding studies on muscle type of creatine kinase from Pelodiscus sinensis.
abstract: A folding study of creatine kinase from Pelodiscus sinensis has not yet been reported. To gain more insight into structural and folding mechanisms of P. sinensis CK (PSCK), denaturants such as SDS, guanidine HCl, and urea were applied in this study. We purified PSCK from the muscle of P. sinensis and conducted inhibition kinetics with structural unfolding studies under various conditions. The results revealed that PSCK was completely inactivated at 1.8 mM SDS, 1.05 M guanidine HCl, and 7.5 M urea. The kinetics via time-interval measurements showed that the inactivation by SDS, guanidine HCl, and urea were all first-order reactions with kinetic processes shifting from monophase to biphase at increasing concentrations. With respect to tertiary structural changes, PSCK was unfolded in different ways; SDS increased the hydrophobicity but retained the most tertiary structural conformation, while guanidine HCl and urea induced conspicuous changes in tertiary structures and initiated kinetic unfolding mechanisms. Our study provides information regarding PSCK and enhances our knowledge of the reptile-derived enzyme folding.
authors.affiliation: College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, PR China.
authors.forename: Su-Fang
authors.initials: SF
authors.lastname: Wang
authors.forename: Yue-Xiu
authors.initials: YX
authors.lastname: Si
authors.forename: Zhi-Jiang
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Shang-Jun
authors.initials: SJ
authors.lastname: Yin
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
authors.forename: Guo-Ying
authors.initials: GY
authors.lastname: Qian
mesh_terms: D000818:Animals; D052283:Creatine Kinase, MM Form / Q000737:chemistry* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D019791:Guanidine / Q000494:pharmacology; D007700:Kinetics; D017510:Protein Folding / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D014426:Turtles; D014508:Urea / Q000494:pharmacology
chemical_list: D012967:Sodium Dodecyl Sulfate; D014508:Urea; D052283:Creatine Kinase, MM Form; D019791:Guanidine