Mechanism of hair curling via laccase-assisted tyrosine grafting using BSA as a model protein

Abstract

Commercial hair perming uses strong reducing agents and harms hair fiber’s quality even human health. In this study, tyrosine is adopted as a crosslinking agent between thiols and/or amines as the shape-changing of hair involves the breakage of disulfide bonds and the rearrangement of new bonds between keratin molecules. To investigate the mechanism of keratin cross-linking, bovine serum albumin (BSA) is used as a model protein. Disulfide bonds in BSA are successfully reduced by L-cysteine to provide free thiols. Four new cross-linked peptides are formed inter- or intra-BSA monomers, indicating that tyrosine can be adopted as a cross-linking agent not only between amines but also between thiols. Moreover, curling of Asian hair is conducted using tyrosine as a perming agent by the laccase-assisted reaction. The optimized operational conditions are hair with L-cysteine pretreatment (50.0 mM) followed by laccase-assisted 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. The curling process could be accomplished without strength loss of hair fibers and with a blow-drier easily. Hence, this new methodology may lead to the development of a gentle and user-friendly approach in the hair care industry.

商业烫发中使用的强力还原剂会损害头发纤维的质量甚至人体健康, 因此, 该研究将酪氨酸用作巯基和/或氨基之间的交联剂, 通过二硫键的断裂和角 蛋白分子间新交联键的重排改变头发的形状. 为了研究角蛋白交联的机理, 将牛血清白蛋白(BSA)用作模型蛋白. BSA中的二硫键成功地被L-半胱氨酸 还原为巯基, 后续的酪氨酸接枝使BSA单体之间或内部形成了四种新的交 联肽段, 表明酪氨酸不仅可以用作氨基之间的交联剂, 也可以促使巯基之间 的交联. 此外, 以酪氨酸为烫发剂对亚洲人发进行卷曲改性. 最佳的实验条 件为头发先经过50.0 mM的L-半胱氨酸预处理, 然后使用漆酶催化3.0 mM的 酪氨酸进行接枝. 改性后头发的卷曲效果优于传统商业烫发, 尽管洗涤后头 发的卷曲程度略有下降, 但在卷曲改性过程中头发的强力几乎没有损失, 并 且该工艺可以用吹风机轻松完成. 因此, 这种温和友好的卷发方法将会促进 美发行业的发展.