Characterization and profiling of human hair keratins

• Main Author: Leung, Ching Yung
• Other Authors: Ng Kee Woei
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/156743
• Institution: Nanyang Technological University

Human hair is a naturally-occurring fibrous material, and distinctions in human hair characteristics of individuals are associated with variations at the molecular level. Although some findings on the relationship between hair keratins and keratin-associated proteins (KAPs) with gender, ethnicity and age have been reported, the number of studies are limited. It is also a challenge to solubilize human hair for effective protein recovery. This project aims to optimize a protein extraction protocol for human hair, and profile the hair keratins and KAPs of individuals across different subpopulations to observe for any hair proteome correlations with gender, ethnicity, and age. Hair samples for this project were contributed by 19 individuals consisting of both females and males between the ages of 20 to 80, across the Chinese, Indian, Malay, and Filipino ethnic groups. Hair proteins were extracted via alkali, sulfitolysis, detergent and detergent-free methods. Hair morphology before and after protein extraction was analysed via scanning electron microscopy (SEM). Protein expressions were characterized and quantified using mass spectrometry (MS). Reduction using sodium dodecyl sulfate (SDS) as a surfactant was identified as the method that was able to obtain the highest hair proteome coverage. Relationships between hair keratins and KAPs with gender, ethnicity, and age were observed. Type II hair keratins were more useful in demonstrating gender differences; abundance of specific KAPs were significantly higher in a particular gender. Certain KAPs were also exclusively expressed in females and males only. Expressions of numerous type I and type II hair keratins, as well as KAPs, were distinctly different between the ethnic groups. For the same protein, the ethnicity which exhibited significantly higher abundance differed between the genders. KAPs were more useful for age profiling as compared to hair keratins. Abundance of various KAPs demonstrated similar trends with increasing age across three sample groups of fixed gender and ethnicity.