College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, P. R. China.
J Biomol Struct Dyn. 2011 Dec;29(3):463-70. doi: 10.1080/07391102.2011.10507398.
Tyrosinase plays various roles in organisms and much research has focused on the regulation of tyrosinase activity. We studied the inhibitory effect of thiobarbituric acid (TBA) on tyrosinase. Our kinetic study showed that TBA inhibited tyrosinase in a reversible noncompetitive manner (K(i) 5 14.0 ± 8.5 mM and IC₅₀ 5 8.0 ± 1.0 mM). Intrinsic and ANS-binding fluorescences studies were also performed to gain more information regarding the binding mechanism. The results showed that no tertiary structural changes were obviously observed. For further insight, we predicted the 3D structure of tyrosinase and simulated the docking between tyrosinase and TBA. The docking simulation was successful with significant scores (binding energy for AutoDock4: -5.52 kcal/mol) and suggested that TBA was located in the active site. The 11 ns molecular dynamics simulation convinced that the four HIS residues (residue numbers: 57, 90, 250, and 282) were commonly responsible for the interaction with TBA. Our results provide a new inhibition strategy that works using an antioxidant rather than targeting the copper ions within the tyrosinase active site.
酪氨酸酶在生物体中发挥着多种作用，许多研究都集中在调节酪氨酸酶活性上。我们研究了硫代巴比妥酸（TBA）对酪氨酸酶的抑制作用。我们的动力学研究表明，TBA 以可逆的非竞争性方式抑制酪氨酸酶（K(i) 为 14.0 ± 8.5 mM，IC₅₀ 为 8.0 ± 1.0 mM）。还进行了本征和 ANS 结合荧光研究，以获取有关结合机制的更多信息。结果表明，没有明显观察到三级结构变化。为了进一步深入了解，我们预测了酪氨酸酶的 3D 结构，并模拟了酪氨酸酶和 TBA 之间的对接。对接模拟非常成功，得分显著（AutoDock4 的结合能为-5.52 kcal/mol），并表明 TBA 位于活性部位。11 ns 分子动力学模拟证实，四个 HIS 残基（残基编号：57、90、250 和 282）通常负责与 TBA 的相互作用。我们的结果提供了一种新的抑制策略，该策略使用抗氧化剂而不是针对酪氨酸酶活性部位内的铜离子。
