Interaction of Polypeptides with Hair in Different Reducing Environments

January 2026 in “ International Journal of Biological Macromolecules ”

José Pedro Carvalho, André F. Costa, Filipa Gonçalves, André da Costa, A Tomé Ribeiro, Madalena A. Martins, Ana Tinoco, Artur Cavaco-Paulo

polypeptides damaged hair reducing environment KP peptide hydrolyzed keratin BSK proteins cysteine cuticle mechanical properties keratin alpha-helix denaturation temperature enthalpy hair fibers keratin

TLDR Small KP peptide improves hair without reducing agents, while larger proteins need them for better results.

The study examines the impact of reducing environments on the interaction of polypeptides with damaged hair, revealing that the KP peptide can effectively penetrate and enhance hair properties without reducing agents. Larger polypeptides, such as hydrolyzed keratin and BSK, which are rich in cysteine, primarily bind to the cuticle and improve hair properties under reducing conditions. ELP-KP showed no significant improvement, likely due to its lower cysteine content. The findings emphasize that both the reducing environment and the polypeptides' cysteine content and molecular weight play crucial roles in their effectiveness for hair repair.

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