Surface Modification of Cellulose Acetate with Cutinase and ...

Enzymatic Hydolysis of Wool with a Genetically Modified Subtilisin E
inside the fibre cortex while chimeric subtilisinE-VPAVG220, with a molecular weight
higher than 116 kDa, appears to be restricted to the surface of yarns (Figure 2A and B).
Silva and collaborators have obtained similar results after chemical modification of
subtilisins with PEG and Eudragit S-100. The chemically modified enzymes presented
molecular weights higher than 97 KDa which appeared to be effective to limit the
hydrolysis only at the wool cortex (Silva et al., 2004; Silva et al., 2005).
Fluorescence microscopy results provide good indication that chimeric subtilisin-
VPAVG220 has the proteolytic activity restricted to wool surface.
A B
Figure 2. Fluorescence microscopy images of fibre cross-sections of wool yarns treated
with FITC-labelled commercial Esperase (A) and chimeric subtilsin-VPAVG220 (B),
(100x).
3.3.2. On yarns tensile strength
The wool fibre cuticle is covered by a covalently bound lipid layer, the main responsible
for the hydrophobicity of wool. Alkaline pre-treatments can partially remove some of
these lipids reducing its hydrophobic nature and enhancing at the same time protein
diffusion inside the fibre (Brack et al., 1999). Wool yarns were then subjected to two
alkaline pre-treatments, a scouring washing (S) and a scouring washing followed by
bleaching (S + B). Wool yarns previously pre-treated were incubated with the same
units of commercial subtilisin and chimeric subtilisin-VPAVG220 for 24 h for tensile
strength resistance valuation.
Figure 3 demonstrate that there are no significant differences in the tensile strength of
yarns subjected to both pre-treatments compared to the control samples.
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