title: Deceleration of arginine kinase refolding by induced helical structures.
abstract: Arginine kinase (AK) is a key metabolic enzyme for keeping energy balance in invertebrates. Therefore, regulation of the enzymatic activity and the folding studies of AK from the various invertebrates have been the focus of investigation. We studied the effects of helical structures by using hexafluoroisopropanol (HFIP) on AK folding. Folding kinetic studies showed that the folding rates of the urea-denatured AKs were significantly decelerated after being induced in various concentrations of HFIP. AK lost its activity completely at concentrations greater than 60%. The results indicated that the HFIP-induced helical structures in the denatured state play a negative role in protein folding, and the helical structures induced in 5% (v/v) HFIP act as the most effective barrier against AK taking its native structure. The computational docking simulations (binding energies for -2.19 kcal/mol for AutoDock4.2 and -20.47 kcal/mol for Dock6.3) suggested that HFIP interacts with the several important residues that are predicted by both programs. The excessively pre-organized helical structures not only hampered the folding process, but also ultimately brought about changes in the three-dimensional conformation and biological function of AK.
authors.affiliation: Zhejiang Provincial Key Laboratory of Applied Enzymology, Yangtze Delta Region Institute of Tsinghua University, Jiaxing, People's Republic of China.
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Li
authors.forename: Sheng-Mei
authors.initials: SM
authors.lastname: Zhou
authors.forename: Daeui
authors.initials: D
authors.lastname: Park
authors.forename: Hyoung Oh
authors.initials: HO
authors.lastname: Jeong
authors.forename: Hae Young
authors.initials: HY
authors.lastname: Chung
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
authors.forename: Fan-Guo
authors.initials: FG
authors.lastname: Meng
authors.forename: Wei-Jiang
authors.initials: WJ
authors.lastname: Hu
mesh_terms: D000818:Animals; D001122:Arginine Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D033561:Penaeidae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D017510:Protein Folding; D017433:Protein Structure, Secondary
chemical_list: D001122:Arginine Kinase