Enzymatic Treatment of Wool with Modified Proteases

strongly acid chlorination step followed by a dechlorination step (subtractive
process) with a subsequent application of a cationic polymer (Hercosett:
polyamide-epichlorohydrin resin) (additive process). The chlorination results
in the oxidation of cystine residues to cysteic acid residues in the surface of
the fiber and allows the cationic polymer to spread and adhere to wool
surface (Lewis 1992; Heine 2002).
The chlorine-Hercosett process has been dominant in the industry for 30
years, and still about 75% by weight of the world's treated wool is processed by
this route in one of its forms (Holme 2003). With respect to efficiency and cost the
chlorine-Hercosett process offers tremendous advantages which are hard to
overcome even with great effort: excellent antifelt effect, purposive modification of
the wool surface, low damage and low weight loss. From today's modern point of
view, however, the chlorine-Hercosett process shows a number of drawbacks
which make the search for an ecologically clean alternative worthwhile: limited
durability, poor handle, yellowing of wool, difficulties in dyeing and the most
important today, environmental impact (release of absorbable organic halogens-
AOX to the effluents) (Heine 2002; Julia et al. 2000; Schlink and Greeff 2001).
Therefore, because of the new environmental directives, the development
of clean technologies such as enzymatic finishing processes is a priority. The
biotechnology applied to textile industry, by the use of enzymes, has already
contributed to a reduction of energy costs and also to the reduction of pollutant
emissions into the environment (Feitkenhauer and Meyer 2001).
Before introducing some of the enzymatic finishing processes already
implemented in the textile industry (section 1.4), a brief description of enzymes
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