Submitted to: International Journal of Biological Macromolecules
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/13/2008
Publication Date: 5/1/2008
Publication URL: http://dx.doi.org/10.1016/j.ijbiomac.2008.02.004
Citation: Cardamone, J.M. Keratin Transamidation. 2008. International Journal of Biological Macromolecules. 42(5):413-419. Interpretive Summary: Wool in traditional markets does not have a competitive market share. However, keratin protein extracted from wool offers a rich resource for biomaterial applications, including applications back onto wool. ARS scientists investigated the feasibility of this concept. Wool was dissolved in caustic solution to free small keratin proteins. The dissolved protein recombined in the presence of wool fabric to form a coating that increased the strength and the dimensional stability of the fabric. The process of recombining and applying keratin was by assistance of an enzyme known to promote the condensation of certain amino acids in wool keratin. By extension of these findings, there is potential to create a wide range of new value-added products useful in biotechnical fields. This research positions wool as a rich feedstock in nontraditional markets.
Technical Abstract: Low molecular weight keratin was self-crosslinked by microbial transglutaminase (mTGase) for application to wool fabric. From amino acid determination, keratin produced by the alkaline hydrolysis of wool showed requisite glutamine and lysine required for mTGase-mediated transamidation. Keratin showed less lysyl amine content after combination with mTGase as proof of self-crosslinking. Gel electrophoretic patterns provided evidence of self-crosslinking with the development of relatively higher molecular weight protein bands within 30 minutes after mTGase was combined with keratin at 30 deg C. Increase in the deconvoluted amide II band from IR spectra of keratin after combination with mTGase provided further evidence of transamidation. By examining the ability of keratin to self-crosslink, past findings were elucidated whereby mTGase-mediated crosslinking imparted strength to wool and keratin controlled its dimensional stability. mTGase-catalyzed isopeptide bond formation of keratin to form monosubstituted gamma-amides of peptide-bound glutamine in epsilon-amino-(gamma-glutamyl)lysine crosslinks. This system was effective for binding wool to wool, keratin to wool, and keratin to keratin in self-crosslinking.