Ochiai Akihito, Tanaka Seiya, Imai Yuta, Yoshida Hisashi, Kanaoka Takumi, Tanaka Takaaki, Taniguchi Masayuki
Department of Materials Science and Technology, Faculty of Engineering, Niigata University, Niigata 950-2181, Japan; Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
J Biosci Bioeng. 2016 Jun;121(6):607-613. doi: 10.1016/j.jbiosc.2015.10.010. Epub 2015 Nov 14.
Tyrosinase, a rate-limiting enzyme in melanin biosynthesis, catalyzes the hydroxylation of l-tyrosine to 3,4-dihydroxy-l-phenylalanine (l-dopa) (monophenolase reaction) and the subsequent oxidation of l-dopa to l-dopaquinone (diphenolase reaction). Thus, tyrosinase inhibitors have been proposed as skin-lightening agents; however, many of the existing inhibitors cannot be widely used in the cosmetic industry due to their high cytotoxicity and instability. On the other hand, some tyrosinase inhibitory peptides have been reported as safe. In this study, we found that the peptide TH10, which has a similar sequence to the characterized inhibitory peptide P4, strongly inhibits the monophenolase reaction with a half-maximal inhibitory concentration of 102 μM. Seven of the ten amino acid residues in TH10 were identical to P4; however, TH10 possesses one N-terminal tyrosine, whereas P4 contains three tyrosine residues located at its N-terminus, center, and C-terminus. Subsequent analysis using sequence-shuffled variants indicated that the tyrosine residues located at the N-terminus and center of P4 have little to no contribution to its inhibitory activity. Furthermore, docking simulation analysis of these peptides with mushroom tyrosinase demonstrated that the active tyrosine residue was positioned close to copper ions, suggesting that TH10 and P4 bind to tyrosinase as a substrate analogue.
酪氨酸酶是黑色素生物合成中的一种限速酶，催化L-酪氨酸羟基化为3,4-二羟基-L-苯丙氨酸（L-多巴）（单酚酶反应）以及随后L-多巴氧化为L-多巴醌（二酚酶反应）。因此，酪氨酸酶抑制剂已被提议用作美白剂；然而，许多现有的抑制剂由于其高细胞毒性和不稳定性而无法在化妆品行业广泛使用。另一方面，一些酪氨酸酶抑制肽已被报道是安全的。在本研究中，我们发现与已鉴定的抑制肽P4具有相似序列的肽TH10强烈抑制单酚酶反应，其半数最大抑制浓度为102μM。TH10的十个氨基酸残基中有七个与P4相同；然而，TH10具有一个N端酪氨酸，而P4在其N端、中心和C端含有三个酪氨酸残基。随后使用序列改组变体进行的分析表明，位于P4 N端和中心的酪氨酸残基对其抑制活性几乎没有贡献。此外，这些肽与蘑菇酪氨酸酶的对接模拟分析表明，活性酪氨酸残基靠近铜离子定位，这表明TH10和P4作为底物类似物与酪氨酸酶结合。
