Research Institute of Pharmaceutical Sciences, College of Pharmacy, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Korea.
Int J Mol Sci. 2021 Dec 20;22(24):13661. doi: 10.3390/ijms222413661.
Coppers play crucial roles in the maintenance homeostasis in living species. Approximately 20 enzyme families of eukaryotes and prokaryotes are known to utilize copper atoms for catalytic activities. However, small-molecule inhibitors directly targeting catalytic centers are rare, except for those that act against tyrosinase and dopamine-β-hydroxylase (DBH). This study tested whether known tyrosinase inhibitors can inhibit the copper-containing enzymes, ceruloplasmin, DBH, and laccase. While most small molecules minimally reduced the activities of ceruloplasmin and DBH, aside from known inhibitors, 5 of 28 tested molecules significantly inhibited the function of laccase, with the K values in the range of 15 to 48 µM. Enzyme inhibitory kinetics classified the molecules as competitive inhibitors, whereas differential scanning fluorimetry and fluorescence quenching supported direct bindings. To the best of our knowledge, this is the first report on organic small-molecule inhibitors for laccase. Comparison of tyrosinase and DBH inhibitors using cheminformatics predicted that the presence of thione moiety would suffice to inhibit tyrosinase. Enzyme assays confirmed this prediction, leading to the discovery of two new dual tyrosinase and DBH inhibitors.
铜在维持生物体内的动态平衡中起着至关重要的作用。目前已知约有 20 种真核生物和原核生物的酶家族利用铜原子进行催化活性。然而，除了针对酪氨酸酶和多巴胺-β-羟化酶（DBH）的抑制剂外，直接针对催化中心的小分子抑制剂非常罕见。本研究测试了已知的酪氨酸酶抑制剂是否可以抑制含铜酶、铜蓝蛋白、DBH 和漆酶。虽然大多数小分子对铜蓝蛋白和 DBH 的活性只有轻微的抑制作用，但除了已知的抑制剂外，28 种测试分子中有 5 种能显著抑制漆酶的功能，其 K 值在 15 到 48 μM 之间。酶抑制动力学将这些分子分类为竞争性抑制剂，而差示扫描荧光法和荧光猝灭支持直接结合。据我们所知，这是首次报道用于漆酶的有机小分子抑制剂。使用计算化学对酪氨酸酶和 DBH 抑制剂进行比较预测，含硫酮部分就足以抑制酪氨酸酶。酶活性测定证实了这一预测，从而发现了两种新的酪氨酸酶和 DBH 双重抑制剂。
