Crystallin Fusion Proteins Improve the Thermal Properties of Hair.

Ana Tinoco,José Gonçalves,Carla Silva,Artur Ribeiro,Artur Cavaco-Paulo

doi:10.3389/fbioe.2019.00298

Ana Tinoco, José Gonçalves + Show 3 more

Open Access

https://doi.org/10.3389/fbioe.2019.00298

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Abstract

Styling hair with straightening irons is a popular daily hair routine that significantly damage the hair keratin fiber due to the high temperature applied. In this study, we investigate the effect of two fusion proteins based on the human eye γD-crystallin conjugated with a keratin-based peptide (KP-Cryst Wt and KP-Cryst Mut) on hair exposed to thermal damage. The mutant form was designed to improve protein stability and promote interaction with the hair. Through the study, it was demonstrated the protection of Asian and Caucasian virgin hair's structure by the pretreatments with the KP-Cryst fusion proteins. After hair thermal exposure, a higher water content was quantified by TGA on the hair fibers pretreated with the fusion proteins (about 38% for the KP-Cryst Wt and 44% for the KP-Cryst Mut). Also, negligible alterations in hair fibers' stiffness were observed after iron application, demonstrating the proteins capacity to effectively prevent the conversion of keratin α-helix structure into β-sheets. The results proved the capacity of the fusion proteins to bind to hair and protect it against high temperatures', supporting the development of new formulations based on the KP-Cryst proteins.

Highlights

Human hair is a highly structured fiber organized in cuticle, cortex and sometimes medulla
Exploring the great thermodynamic stability of this protein, we aim to develop new formulations to improve hair mechanical performance while protecting the hair fiber from damage resultant from the exposition to high temperatures
The two crystallins were fused with a keratin-binding peptide (KP) (Cruz et al, 2017) and a (GA)5 linker (Gonçalves et al, 2018c) to promote the binding of the proteins to the hair cuticle and cortex and impart the constructs with structural mobility, respectively

Summary

Introduction

Human hair is a highly structured fiber organized in cuticle, cortex and sometimes medulla. Styling the hair with straightening irons or curling tongs is nowadays a popular daily hair routine (Christian et al, 2011), during these procedures, hair strands are put in contact with excessive heat (usually between 150 and 250◦C) causing the disulfide bonds to break (Ettlinger et al, 2014). The popularity of straightening irons and curling tongs has created a large market for hair products associated with heat styling, including heat-protection sprays, straightening balms, curl creams, and heat-protection shampoos/conditioners (Christian et al, 2011) These heat-protecting products are able to form film-like structures over the hair fibers, smoothing hair’s imperfections and help protect the hair from extreme internal water loss caused by higher temperatures or long exposure time (Crudele et al, 1999)

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