Surface Modification of Cellulose Acetate with Cutinase and ...

General Discussion and Future Perspectives
activity on PET when compared with the native enzyme (Subchapter 2.3- Silva et al.,
2007 and Subchapter 2.4- O’Neill et al., 2007).
Similarly the activity of a nylon-oligomer hydrolysing enzyme EII’ from
Flavobactererium sp. was increased 200-fold by genetic engineering (Negoro, 2000).
In addition to genetic engineering, reaction engineering (temperature and additives)
seems to be an important factor and enzymatic hydrolysis of PA can be increased in
the presence of solvents (Silva et al., 2005a).
Not only the structural design of the active site of the enzymes but also the regions
required for sorption and for guiding the enzyme along the substrate, might be
important for polymer hydrolysis. Cellulose-binding modules (CBM) accomplish this
role in cellulases. For this reason, the biomodification of the surface of cellulose
acetate was performed with cutinase fused with either the carbohydrate-binding
module of Cellobiohydrolase I, from the fungi Trichoderma reesei, or the
carbohydrate-binding module of Endoglucanase C, from the bacteria Cellulomonas
fimi. The knew recombinant cutinase fused to the fungal CBM presented better
performance hydrolysing cellulose diacetate and improving the colour levels of
treated fabrics (Subchapter 2.5- Matamá et al., 2008).
The second part of this thesis relates to the biomodification of wool, to accomplish
total easy care wool i.e. machine washability plus tumble dryability, to compete with
other fibres.
The traditional method to confer dimensional stability to wool articles uses chlorine
which has various drawbacks. Several enzymatic methods have been attempted to
replace this hazardous chemical finishing treatment, without great success mainly
due to diffusion of enzyme into wool cortex (Shen et al., 1999). Chemical
modification of proteases proved to be effective for wool finishing, however the
presence of small amounts of free enzyme still representes a drawback (Silva et al.,
2004; Silva et al., 2005b). In our work we used subtilisin E from Bacillus subtilis,
genetically modified, in order to avoid its penetration inside the fibre.
The first attempt was to create a chimeric poly-subtilisinE composed of 2, 3 and 4
subtilisin units. Chimeric subtilisins were overexpressed but no active and soluble
recombinant proteins were recovered (Subchapter 3.2- Araújo et al., 2008a). The
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