title: Kinetics for Zinc Ion Induced Sepia Pharaonis Arginine Kinase Inactivation and Aggregation.
abstract: Arginine kinase is an essential enzyme which is closely related to energy metabolism in marine invertebrates. Arginine kinase provides a significant role in quick response to environmental change and stress. In this study, we simulated a tertiary structure of Sepia pharaonis arginine kinase (SPAK) based on the gene sequence and conducted the molecular dynamics simulations between SPAK and Zn(2+). Using these results, the Zn(2+) binding sites were predicted and the initial effect of Zn(2+) on the SPAK structure was elucidated. Subsequently, the experimental kinetic results were compared with the simulation results. Zn(2+) markedly inhibited the activity of SPAK in a manner of non-competitive inhibitions for both arginine and ATP. We also found that Zn(2+) binding to SPAK resulted in tertiary conformational change accompanying with the hydrophobic residues exposure. These changes caused SPAK aggregation directly. We screened two protectants, glycine and proline, which effectively prevented SPAK aggregation and recovered the structure and activity. Overall, our study suggested the inhibitory effect of Zn(2+) on SPAK and Zn(2+) can trigger SPAK aggregation after exposing large extent of hydrophobic surface. The protective effects of glycine and proline against Zn(2+) on SPAK folding were also demonstrated.
authors.forename: Yue-Xiu
authors.initials: YX
authors.lastname: Si
authors.forename: Jinhyuk
authors.initials: J
authors.lastname: Lee
authors.forename: Juan-Ge
authors.initials: JG
authors.lastname: Cheng
authors.forename: Shang-Jun
authors.initials: SJ
authors.lastname: Yin
authors.forename: Yong-Doo
authors.initials: YD
authors.lastname: Park
authors.affiliation: College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, P.R China. qianguoying_wanli@hotmail.com.
authors.forename: Guo-Ying
authors.initials: GY
authors.lastname: Qian
authors.affiliation: School of Marine Sciences, Ningbo University, Ningbo 315211, P.R. China. jiangxiamin@nbu.edu.cn.
authors.forename: Xia-Min
authors.initials: XM
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001122:Arginine Kinase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D004734:Energy Metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D049833:Sepia / Q000201:enzymology* / Q000378:metabolism; D015032:Zinc / Q000737:chemistry*
chemical_list: D001122:Arginine Kinase; D015032:Zinc