Study of Mechanisms of Recombinant Keratin Solubilization with Enhanced Wound Healing Capability

Despite the long-term use and recent development of keratin materials, the mechanism of their solubilization is still not well understood beyond the breakage of disulfide bonds due to the complexity of extracted proteins. Herein, the solubilization of recombinant keratins was separately performed following the keratin extraction procedures to elucidate the chemistry behind the keratin extraction process and to enhance their wound healing capability. Keratin solubilization was attributed to the disulfide bonds broken and the chemical reaction of amino acids. First, an approximately 50% decrease in disulfide bonds in recombinant keratins was found after reduction, but the content of disulfide bonds in soluble keratins is not in direct proportion to their hydrophilicity. Second, a decrease in the molecular weight of recombinant keratins after reduction was noted due to the chemical reaction of amino acids. Relatively high stability of proline, leucine, and histidine was observed, while other amino acids, especially cysteine and arginine, were partially reduced and hydrolyzed primarily in the random coil domains. More importantly, the soluble recombinant keratins with high purity and hydrophilicity displayed stronger wound healing capability in vivo compared to that of the recombinant keratins and extracts.