Abstract
Tyrosinase, a key copper-containing enzyme involved in melanin biosynthesis, is closely associated with hyperpigmentation disorders, cancer, and neurodegenerative diseases, and as such, it is an essential target in medicine and cosmetics. Known tyrosinase inhibitors possess adverse side effects, and there are no safety regulations; therefore, it is necessary to develop new inhibitors with fewer side effects and less toxicity. Peptides are exquisitely specific to their in vivo targets, with high potencies and relatively few off-target side effects. Thus, we systematically and comprehensively investigated the tyrosinase-inhibitory abilities of N- and C-terminal cysteine/tyrosine-containing tetrapeptides by constructing a phage-display random tetrapeptide library and conducting computational molecular docking studies on novel tyrosinase tetrapeptide inhibitors. We found that N-terminal cysteine-containing tetrapeptides exhibited the most potent tyrosinase-inhibitory abilities. The positional preference of cysteine residues at the N terminus in the tetrapeptides significantly contributed to their tyrosinase-inhibitory function. The sulfur atom in cysteine moieties of N- and C-terminal cysteine-containing tetrapeptides coordinated with copper ions, which then tightly blocked substrate-binding sites. N- and C-terminal tyrosine-containing tetrapeptides functioned as competitive inhibitors against mushroom tyrosinase by using the phenol ring of tyrosine to stack with the imidazole ring of His263, thus competing for the substrate-binding site. The N-terminal cysteine-containing tetrapeptide CRVI exhibited the strongest tyrosinase-inhibitory potency (with an IC50 of 2.7 ± 0.5 μM), which was superior to those of the known tyrosinase inhibitors (arbutin and kojic acid) and outperformed kojic acid–tripeptides, mimosine-FFY, and short-sequence oligopeptides at inhibiting mushroom tyrosinase.
Footnotes
- Received June 8, 2014.
- Accepted November 17, 2014.
N.-W.H. and T.-S.T. contributed equally to this work.
This work was supported by the National Research Institute of Chinese Medicine, Ministry of Health and Welfare [MM10211-0153 and MOHW103-NRICM-D-305-122205], the National Science Council [NSC 100-2320-B-077-004-MY2 and NSC 103-2320-B-077-001-MY3 to K.-C.T.], and Ministry of Health and Welfare [MOHW103-TD-B-111-01 from health and welfare surcharge of tobacco products], Taipei, Taiwan.
↵This article has supplemental material available at molpharm.aspetjournals.org.
- Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics
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