Keratins and lipids in ethnic hair

The study investigated the molecular structure of human hair using high-resolution X-ray diffraction, focusing on differences between individuals, including genetic similarities. Despite a small sample size of 12 individuals, the research found that the general molecular features of hair, such as the coiled-coil phase of α-helical keratin proteins and lipid layers, were consistent across all samples. However, variations in lipid types were noted, suggesting genetic influence, as identical patterns appeared in hair from genetically similar individuals like identical twins and a father-daughter pair, but not in fraternal twins. These findings highlighted the potential of using hair's molecular structure as a diagnostic tool for diseases.

The study examined the content and distribution of lipids in African, Asian, and Caucasian hair, focusing on how these lipids interact with keratin, the main structural protein in hair. It was found that African hair contained a higher percentage of internal lipids compared to other ethnic hair types. This higher lipid content influenced the structure of keratin, as evidenced by the absence of axial diffraction in X-ray analysis, which returned to normal after lipid removal. Molecular dynamics simulations showed that lipids intercalated with keratin dimers, altering their structure. The study concluded that the keratin structure in African hair might be influenced by its higher lipid concentration.