Effect of Cd²⁺ on tyrosinase: Integration of inhibition kinetics with computational simulation

详细信息    查看全文

• 作者：Li-Mei Yue^a ; ¹ ; Jinhyuk Lee^b ; ^c ; ¹ ; Zhi-Rong Lü ; ^d ; Jun-Mo Yang^e ; Zhuo-Ming Ye^a ; ^{zhuomingye@hotmail.com} ; Yong-Doo Park^d ; ^f ; ^{parkyd@hotmail.com}
• 关键词：L-DOPA ; 3 ; 4-dihydroxyphenylalanine ; ANS ; 1-anilinonaphthalene-8-sulfonate ; MD ; molecular dynamics
• 刊名：International Journal of Biological Macromolecules
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：94
• 期：part_PB
• 页码：836-844
• 全文大小：2404 K
• 卷排序：94

文摘

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 IC50 of 2.92 ± 0.16 mM and Ki of 0.23 ± 0.02 mM. 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.