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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Effect <strong>of</strong> the Agitation on the Adsorption <strong>and</strong> Hydrolytic Efficiency <strong>of</strong> <strong>Cutinase</strong>s on Polyethylene Terephthalate fibres<br />
(600 nm) as an average <strong>of</strong> five readings. The control samples were incubated in<br />
phosphate buffer solution.<br />
2.6. Protein adsorption <strong>and</strong> desorption<br />
The remaining protein in the enzymatic treatment solution for different incubation<br />
periods was measured to study the adsorption <strong>and</strong> desorption phenomena (Araújo et al.,<br />
2007). For this adsorption/desorption studies the protein in solution was determined by<br />
the Bradford method using bovine serum albumin (BSA) as st<strong>and</strong>ard (Bradford, 1976).<br />
Different time samples <strong>of</strong> enzymatic treatment solution were measured (0, 1, 2, 3, 4 <strong>and</strong><br />
5 h). After 5 h <strong>of</strong> incubation, the enzymatic treatment solution was diluted (1:2) <strong>with</strong> the<br />
same previously specified phosphate buffer <strong>and</strong> the mixture was subsequent incubated<br />
for another 60 minutes, <strong>with</strong> the same agitation <strong>and</strong> temperature conditions, to verify the<br />
desorption phenomena. Values had a st<strong>and</strong>ard deviation below 9%. The percentage <strong>of</strong><br />
adsorption was calculated by the following expressions as described in literature<br />
(Azevedo et al., 2000):<br />
A − B<br />
× 100<br />
% adsorption = A<br />
D − C<br />
× 100<br />
% desorption = A<br />
Where: A – initial protein concentration (at 0 h); B – protein concentration at time t (1,<br />
2, 3, 4 <strong>and</strong> 5 h); C – dilution (dilution 1:2 <strong>with</strong> buffer solution); D – final protein<br />
concentration (after the dilution <strong>and</strong> 60 more minutes <strong>of</strong> incubation).<br />
3. Results <strong>and</strong> Discussion<br />
The formation <strong>of</strong> terephthalic acid (TPA) <strong>and</strong> the protein adsorption for the two studied<br />
cutinases, <strong>with</strong> a low agitation level (shaker bath, 2A) <strong>and</strong> strong agitation level<br />
(Rotawash, 2B), is shown in figure 1. In table 1 the values <strong>of</strong> percentage <strong>of</strong> protein<br />
adsorbed for the different incubation periods are shown for both modes <strong>of</strong> mechanical<br />
agitation.<br />
(1)<br />
(2)<br />
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