Surface Modification of Cellulose Acetate with Cutinase and ...
Surface Modification of Cellulose Acetate with Cutinase and ...
Surface Modification of Cellulose Acetate with Cutinase and ...
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General Introduction: Application <strong>of</strong> Enzymes for Textile Fibres Processing<br />
After weaving, the applied sizing agent <strong>and</strong> the natural non-cellulosic materials present<br />
in the cotton must be removed in order to prepare the fabric for dyeing <strong>and</strong> finishing.<br />
Before the discovery <strong>of</strong> amylases, this process (desizing) used to be carried out by<br />
treating the fabric <strong>with</strong> chemicals such as acids, alkali or oxidising agents at high<br />
temperatures. The chemical treatment was not totally effective in removing the starch<br />
(which leads to imperfections in dyeing) <strong>and</strong> also resulted in a degradation <strong>of</strong> the cotton<br />
fiber conducting to destruction <strong>of</strong> the natural, s<strong>of</strong>t feel <strong>of</strong> the cotton.<br />
Nowadays amylases are currently commercialized (MAPS, India) <strong>and</strong> preferred for<br />
desizing due to their high efficiency <strong>and</strong> specific action. Amylases bring about complete<br />
removal <strong>of</strong> the size <strong>with</strong>out any harmful effects on the fabric (Etters <strong>and</strong> Annis, 1998;<br />
Cegarra, 1996). The starch is r<strong>and</strong>omly cleaved into water soluble dextrins that can be<br />
then removed by washing. The utilization <strong>of</strong> harsh chemicals in the textile desizing was<br />
substituted by amylases resulting in a lower discharge <strong>of</strong> waste chemicals to the<br />
environment <strong>and</strong> improved the safety <strong>of</strong> working conditions for textile workers.<br />
5. Pectinases<br />
Pectin <strong>and</strong> other peptic substances are complex polysaccharides present in plant cell<br />
wall as a part <strong>of</strong> middle lamella. Pectinolytic enzymes or pectinases are a complex<br />
group <strong>of</strong> enzymes involved in the degradation <strong>of</strong> pectic substances. They are primarily<br />
produced in nature by saprophytes <strong>and</strong> plant pathogens (bacteria <strong>and</strong> fungi) for<br />
degradation <strong>of</strong> plant cell walls (Lang <strong>and</strong> Dörenberg, 2000; Bateman, 1966). There are<br />
three major classes <strong>of</strong> pectin degrading enzymes: pectin esterases (PEs),<br />
polygalacturonases (PGs) <strong>and</strong> polygalacturonate lyases (PGLs).<br />
Pectin esterases are mainly produced in plants such as banana, citrus fruits <strong>and</strong> tomato<br />
<strong>and</strong> also by bacteria <strong>and</strong> fungi (Hasunuma et al., 2003). Pectin esterase catalyzes<br />
deesterification <strong>of</strong> the methyl group <strong>of</strong> pectin, forming pectic acid. The enzyme acts<br />
preferentially on a methyl ester group <strong>of</strong> galacturonate unit next to a non-esterifed<br />
galacturonate unit. The molecular weight <strong>of</strong> most microbial <strong>and</strong> plant PEs varies<br />
between 30 – 50 kDa (Hadj-Taieb et al., 2002; Christensen et al., 2002). The optimum<br />
pH for activity varies between 4.0 <strong>and</strong> 7.0. The exception is PE from Erwinia whose<br />
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