Enzyme-mediated Crosslinking of Wool. Part II: Keratin and Transglutaminase

Abstract

Keratin hydrolysates (KH) and their lyophilized powders (KP) were applied with transglutaminase (amine γ-glutamyltransferase EC 2.3.2.13; TG) to fine jersey wool fabric bleached by peroxycarboximidic acid in the first step of the ARS process. The full ARS process involving treatment with proteolytic enzyme (Esperase 8.0L™) after pretreatment by bleaching can result in up to 18% fabric strength loss in fine-gage jersey knits, yet the ARS process has met with industry acceptance. To alleviate strength loss we applied solutions of KH and KP in combination with TG as a transferase enzyme to catalyze transamidation reactions involving keratin as KH and KP and keratinaceous wool fabric in order to provide crosslinking between and among these keratin constituents. Treatments of KH from 100% to 10% owb with TG showed that shrinkage could be controlled; application of 6% owf KP and 2% owf TG controlled shrinkage to 4.89%. Scanning electron micrographs showed that the keratin material coated the fibers to fill the raised scales of the wool. The results of statistical analysis predicted the optimum application conditions of 5% KP and 5% TG. These conditions minimized felting shrinkage to 5.21% and fabric weight change to 0.26% and maximized dry burst strength to 4.7% loss and increase in fabric whiteness to 17.8 whiteness index units. Wool material, including hydrolysates and powders crosslinked by TG enzyme mediation can provide a rich resource for the production of modified keratin-based biomaterials.

Enzyme-mediated coupling of a bi-functional phenolic compound onto wool to enhance its physical, mechanical and functional properties

“…Therefore, the differential friction effect is reduced with concomitant reduced felting shrinkage [32]. The improvement of wool shrink resistance and fibres strength by transglutaminase mediated croslinking on wool protein was also reported by other authors [33,34]. A 5 % increase in the crease recovery angle (CRA) of the fabrics was further observed.…”

Antibacterial Functionalization of Wool via mTGase-Catalyzed Grafting of ε-Poly-l-lysine

“…The products of the acyl transfer reaction, ammonia gasses, are difficult to determine due to its small amount and possible adsorption by the wool fibers. This could be demonstrated by several previous reports involving TGase-catalyzed modification of wool [14][15][16][17], which did not determine the formation of ammonia to verify the grafting but used some indirect methods such as the changes in mechanical properties of wool. In addition, it seems that the graft yield of ε-PLs is very low.…”

“…To date, different types of enzymesincluding proteases [7][8][9], lipases [10], laccases [11], peroxidase [12], tyrosinases [12,13], and transglutaminases [14][15][16][17]-have been used for improving the qualities of wool fabrics or providing new functions to wool. However, as far as our knowledge goes, no report has so far involved the enzymatically antibacterial functionalization of wool textiles.…”

“…It has been proven that TGases could catalyze the intermolecular cross-linking of the wool macromolecules [14,17], which decreased the propensity of wool fabrics to shrink and remedied the strength loss caused by chemically or enzymatically shrink-resistant treatments. Furthermore, to improve physical and mechanical properties of wool fabrics, two types of regenerative proteins, silk proteins (sericin and commercial silk digest) and wool keratins, were grafted on the wool substrates using TGases, which serve as protein cross-linking enzymes [15,16].…”

Keratin transamidation

“…In a previous report, when solubilized keratin and microbial transglutaminase (mTGase) were applied to wool fabric after fabric bleaching with an activated peroxide, peroxycarboximidic acid, the dimensional stability of the fabric was controlled to less than 5% area shrinkage [1]. Originally mTGase as an after treatment was found to impart added strength to wool fabric that had been bleached with activated peroxycarboximidic acid and subsequently treated with protease in the novel ARS process for bleaching, biopolishing, and shrinkproofing wool [2,3].…”