Keratin transamidation

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 min after mTGase was combined with keratin at 30 °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 γ-amides of peptide-bound glutamine in ɛ-amino-(γ-glutamyl)lysine crosslinks. This system was effective for binding wool to wool, keratin to wool, and keratin to keratin in self-crosslinking.