title: Effect of Cd2+on tyrosinase: Integration of inhibition kinetics with computational simulation.
abstract: Cadmium ions (Cd2+) are a widespread and easily absorbed toxin to both humans and animals that can be spread via food, water, and air pollution. Tyrosinase (EC 1.14.18.1) is a multifunctional copper-containing enzyme that is ubiquitously expressed in animals and plays a critical role in melanin production. We evaluated the toxic effects of Cd2+on tyrosinase activity and conformation by measuring kinetics and computationally simulating the interactions. We found Cd2+to be a slope-hyperbolic noncompetitive-inhibition reversible inhibitor of tyrosinase, with an IC50of 2.92±0.16mM and Kiof 0.23±0.02mM. Spectrofluorimetric measurements of intrinsic and ANS-binding fluorescence showed that Cd2+did not induce significant changes to tyrosinase overall or to its regional active site conformations. Cd2+showed its inactivation effect not by modulating apparent structural changes to tyrosinase, but by occupying binding sites. To gain further insight into the Cd2+/tyrosinase interaction, we performed computational docking and molecular dynamics simulations. The results consistently indicated that Cd2+can interact with several residues near the tyrosinase active site, primarily HIS85 and ASN260. Our study provides insight into the mechanism of the toxic effects Cd2+has on tyrosinase, which could affect the normal pigmentation pathway in animals.
authors.affiliation: Department of Radiation Medicine, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangdong, Guangzhou 510515, People's Republic of China.
authors.forename: Li-Mei
authors.initials: LM
authors.lastname: Yue
authors.affiliation: Korean Bioinformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea; Department of Nanobiotechnology and Bioinformatics, University of Sciences and Technology, Daejeon 305-350, Republic of Korea.
authors.forename: Jinhyuk
authors.initials: J
authors.lastname: Lee
authors.affiliation: Zhejiang Provincial Key Laboratory of Applied Enzymology, Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314006, PR China.
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Lü
authors.affiliation: Department of Dermatology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul 135-710, Republic of Korea.
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
authors.affiliation: Department of Radiation Medicine, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangdong, Guangzhou 510515, People's Republic of China. Electronic address: zhuomingye@hotmail.com.
authors.forename: Zhuo-Ming
authors.initials: ZM
authors.lastname: Ye
authors.affiliation: Zhejiang Provincial Key Laboratory of Applied Enzymology, Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314006, PR China; College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, PR China. Electronic address: parkyd@hotmail.com.
authors.forename: Yong-Doo
authors.initials: YD
authors.lastname: Park
mesh_terms: D001216:Asparagine / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry*; D020134:Catalytic Domain; D002413:Cations, Divalent; D004791:Enzyme Inhibitors / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D002413:Cations, Divalent; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D002104:Cadmium; D006639:Histidine; D001216:Asparagine; D014442:Monophenol Monooxygenase
keywords: Cd(2+); Molecular dynamics; Tyrosinase inhibition