College of Biology and Science, Sichuan Agriculture University, Chengdu 611130, PR China.
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.
Int J Biol Macromol. 2017 Aug;101:59-66. doi: 10.1016/j.ijbiomac.2017.03.073. Epub 2017 Mar 16.
Oxaloacetic acid (OA) is naturally found in organisms and well known as an intermediate of citric acid cycle producing ATP. We evaluated the effects of OA on tyrosinase activity and structure via integrating methods of enzyme kinetics and computational simulations. OA was found to be a reversible inhibitor of tyrosinase and its induced mechanism was the parabolic non-competitive inhibition type (IC=17.5±0.5mM and K=6.03±1.36mM). Kinetic measurements by real-time interval assay showed that OA induced multi-phasic inactivation process composing with fast (k) and slow (k) phases. Spectrofluorimetry studies showed that OA mainly induced regional changes in the active site of tyrosinase accompanying with hydrophobic disruption at high dose. The computational docking simulations further revealed that OA could interact with several residues near the tyrosinase active site pocket such as HIS61, HIS259, HIS263, and VAL283. Our study provides insight into the mechanism by which energy producing intermediate such as OA inhibit tyrosinase and OA is a potential natural anti-pigmentation agent.
草酰乙酸（OA）是生物体中天然存在的一种物质，作为柠檬酸循环的中间产物，它能够产生 ATP。我们通过整合酶动力学和计算模拟方法，评估了 OA 对酪氨酸酶活性和结构的影响。结果表明，OA 是酪氨酸酶的可逆抑制剂，其诱导机制为抛物线非竞争性抑制类型（IC=17.5±0.5mM，K=6.03±1.36mM）。实时间隔测定的动力学测量表明，OA 诱导多相失活过程，由快（k）和慢（k）相组成。荧光光谱研究表明，OA 主要在高剂量时诱导酪氨酸酶活性部位的局部变化，同时伴随疏水性破坏。计算对接模拟进一步表明，OA 可以与酪氨酸酶活性部位口袋附近的几个残基相互作用，如 HIS61、HIS259、HIS263 和 VAL283。我们的研究深入了解了能量产生中间体（如 OA）抑制酪氨酸酶的机制，OA 是一种有潜力的天然美白剂。
