Surface Modification of Cellulose Acetate with Cutinase and ...

Subchapter 2.3
In the same set of experiments described was used a shaker bath with orbital agitation.
In this apparatus the polyamide samples were incubated for a long period (48 hours) at
90 strokes per minute. A slow kinetic of enzymatic activity in the first 24 hours of
incubation was obtained. After this period the activity of cutinase increased reaching the
same level of the one obtained on the Rotawash machine (vertical agitation), without
discs (Figure 2).
96
Protein in solution (%)
105
0,150
100
Protein in solution
95
90
85
Amines in solution
0,125
80
75
0,100
70
65
60
0,075
55
50
0,050
45
40
35
Vertical agitation (with discs)
Vertical agitation (no discs)
Orbital agitation
0,025
30
0,000
0 1 2 3 4 5 6 25 30 35 40 45 50 55
Time of incubation (h)
Figure 2. Native cutinase (78 U mL -1 ) activity (measured as amines released to the bath
treatment) vs protein adsorption.
The results of reactive staining obtained for vertical agitation, as well as the results
obtained for orbital agitation show that the incorporation of discs on the system
increased the release of the amines to the bath system (Figure 3). The K/S values
decreased when a higher level of mechanical agitation was applied.
Adsorption studies were also performed in order to measure the influence of mechanical
agitation on the protein adsorption on the fibres. The results given in Figure 2 show that
protein adsorption increased when stainless steel discs were included in the system,
[Amines] (mM)