Mechanism of Laccase-assisted Tyrosine Grafting on Keratin using BSA as
a Model Protein
Abstract
Commercial hair perming uses strong reducing agents and is harmful to
hair fiber’s quality even human health. In this study, tyrosine is
adopted as a cross-linking agent between thiols as the shape-changing of
hair involves breakage of disulfide bonds and the rearrangement of new
bonds between keratin molecules. To investigate the mechanism of the
cross-linking, bovine serum albumin (BSA) is used as a model protein.
Molecular dynamics simulations give an insight on Cys solvent
accessibility and protein stability for the wild type BSA and a designed
BSA presenting the three broken disulfide bonds. A new cross-linked
peptide, NECFLSHK-Tyrosine-Tyrosine-GACLLPK, inter- or intra- BSA
monomers is formed, whose reactive cysteine residues are Cys-101 and
Cys-176. Moreover, curling of Asian hair is conducted using tyrosine as
a perming agent by laccase-assisted reaction. The optimized operational
conditions are hair with cysteine pre-treatment (50.0 mM) followed by
grafting with 3.0 mM tyrosine. The reshaped hair performed a better
perming performance than commercial perming product before washing,
although a lower perming efficiency after washing, however without
strength loss and could be easily accomplished with a blow-drier. Hence,
this new methodology may lead to the development of a gentle and
user-friendly approach in the hair care industry.