Page 200 - Advances in Textile Biotechnology

Enzymatic treatment of wool and silk fi bres 181

The EU funded PROTEX project (contract no.: G1RD-CT-2002-00695)
has developed a new approach by increasing the size of proteases in order

to limit the enzymatic degradation of wool fibre to its cuticlar scales
(Cavaco-Paulo and Silva, 2003; Silva et al., 2004, 2005, 2006; Smith et al.,
2008). The increase in the size of the proteases was achieved by covalently
attaching them to soluble Eudragit polymer (an enteric copolymer of meth-
acrylic acid–methyl methacrylate). This chemical modifi cation of proteases
with Eudragit improved the thermal stability of the enzymes as well as
enzyme recycleability owing to soluble–insoluble reversibility of the

Eudragit polymer attached to the enzyme. Modification of the enzyme was
further developed through a genetic engineering approach to enlarge the
size of proteases in a larger EU project ENZUP (contract No. 032877-
ENZUP) under the 6th EU Framework Programme. Detailed information
on the genetic engineering of proteases is given in chapter 1 and recent
publications (Araújo et al., 2009; Cavaco-Paulo et al., 2009).
Shen et al. (2007) have published the results from bulk trials on wool

fabrics carried out using the modified proteases. It was shown that the

modification of the protease enabled the reaction of the enzyme with wool
to be controlled, so that less degradation of the wool occurred compared

with similar treatments with the unmodified protease. An anti-felting effect

was achieved without any significant weight loss during the treatment. This
novel enzymatic process leads to environmentally friendly production of
machine-washable wool. Lenting et al. (2009) reported the industrial trials

of wool fibres treated with modified proteases, and processed the treated
wool as filling in the production of duvets. The machine-washability of these

wool fi bre-filled duvets was tested in a household washing machine using
both the wool and normal wash programmes. The substantial improvement
in shrink-resistance was achieved even at the high temperature of the
normal washing programme. However, the treatment of the wool fi bres with
modified enzymes showed less impact on maintenance of the thickness of

a fl eece filling during machine washing.
Alternatively, transglutaminases (EC 2.3.2.13) have been used for protein
crosslinking within the fibres to compensate for the reduction of tensile

strength and degradation of wool during treatment with an oxidative agent
(e.g. chlorination for shrinkage prevention), a reducing agent (sodium

sulfite) and/or a protease (Cortez et al., 2004; Du et al., 2007; Griffi n et al.,
2002b; McDevitt and Winkler, 1998). It was reported that treatment of wool
with transglutaminases can slightly reduce the tendency to felting of wool
without causing any negative effect of stiff and harsh handle. Hossain et al.
(2008) used simultaneous protease and transglutaminase treatment of
woven wool fabrics in a single bath. It was reported that the treatment
reduced the felting tendency of woven wool fabrics by 9% with only 2%
weight loss and tensile strength loss. Cardamone (2007) reported that the

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