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.