Submitted to: Textile Research Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/13/2006
Publication Date: 4/1/2007
Citation: Cardamone, J.M. 2007. Enzyme-mediated crosslinking of wool part I: transglutaminase. Textile Research Journal. 77(4):214-221. Interpretive Summary: Shrinkproofing wool to control felting and dimensional stability usually requires oxidative bleaching and enzymatic digestion. The ARS process utilizing oxidation and enzyme treatment can result in up to 18% fabric strength loss. When a common crosslinking enzyme, transglutaminase, was applied to ARS-processed wool fabrics, up to 5% strength was regained. Proof of the effectiveness of applying this enzyme was shown in the infrared spectra of the treated fabrics. The spectra revealed the chemical changes in the reactive groups of wool’s dominant protein, keratin, that are involved in this type of crosslinking. The chemical properties of wool that make it dyeable and available to other chemical finishing processes were not affected. These results lay the groundwork for other chemical changes in wool designed not only to improve physical properties but also to produce novel value-added wool products.
Technical Abstract: Felting shrinkage of wool fabric can be controlled by oxidation and protease treatment but strength loss usually results. The ARS process provides bleaching, biopolishing, and shrinkage control after applying peroxycarboximidic acid oxidation and selective enzyme digestion. Fabric strength loss of from 10% to 18 % can result in fine-gage knit fabrics. After the application of microbial transglutaminase (TG) to ARS-processed wool fabric 3% to 5% fabric strength was regained. The TG transferase-mediated acyltransfer reaction provides crosslinking between glutamine and lysine to form carboxylamide groups of peptide-bound glutamine in wool keratin. Changes in the specular reflectance FTIR spectra of the treated fabrics revealed changes in the amide I and II regions of keratin which were attributed to the functional groups involved in the crosslinking reaction of transamidation. Confocal fluorescence microscopy showed no influence of TG on the anionic charge imparted by peroxycarboximidic acid oxidation. Scanning electron microscopy showed no influence of TG on the scale smoothing or removal imparted by the ARS process. Confocal microscopy further revealed the abundant presence of amine groups in the TG-treated fibers. Thus there is evidence that ARS-processed keratin substrates in the solid state can be self-cross-linked and that they have potential for further reactivity.