Figure 1.
FTIR spectra of MSG, (A) MSG with surface modification; (B) MSG without surface modification.
Figure 2.
The effects of (a) enzyme solution pH; (b) the ratio of enzyme and silica gel; (c) adsorption time on the enzyme activity.
Figure 3.
The effects of cross-linking time (a) and GA concentration (b) on the activity of MSG-CLEAs.
Table 1.
The effect of precipitants on PAL activity.
Figure 4.
SEM images of (A) modified MSG magnified 40000×; (B) MSG -CLEAs- magnified 40000×; (C) modified MSG magnified 100000×; (D) MSG-CLEAs magnified 100000×.
Figure 5.
The optimal pH curves of MSG-CLEAs.
Enzyme activity was determined according to described in the PAL activity assay section. The enzymatic activity which corresponds to 100% activity is 1.5 U/g and 0.9 U/g wet derivative for the CLEAs and MSG-CLEAs, and 4.5 U/g for the soluble enzyme.
Figure 6.
The optimal temperature curves of MSG-CLEAs.
Enzyme activity was determined according to described in the PAL activity assay section. The enzymatic activity which corresponds to 100% activity is 0.36 U/g and 0.43 U/g wet derivative for the CLEAs and MSG-CLEAs, and 1.3 U/g for the soluble enzyme.
Table 2.
Kinetic parameters of free PAL, PAL-CLEAs and MSG-CLEAs.
Figure 7.
Stability of free-PAL, PAL-CLEAs and MSG-CLEAs against chemical denaturants.
Free PAL and immobilized enzyme were stored in urea (6 M), sodium dodecyl sulfate (SDS, 2%, w/v) or ethanol (40%, v/v) in 0.2 M phosphate buffer (pH 7.0) at 30°C for 30 min, respectively. The enzymatic activity which corresponds to 100% activity is 0.36 U/g and 0.43 U/g wet derivative for the CLEAs and MSG-CLEAs, and 1.3 U/g for the soluble enzyme.
Figure 8.
The thermal stability of free-PAL, PAL-CLEAs and MSG-CLEAs at different temperatures.
At different incubation times, samples of immobilized enzyme stored in 0.2 M phosphate buffer (pH 7.0) without substrate at 60uC were withdrawn and assayed for activity by described in the experimental section. The enzymatic activity which corresponds to 100% activity is 0.36 U/g and 0.43 U/g wet derivative for the CLEAs and MSG-CLEAs, and 1.3 U/g for the soluble enzyme.
Figure 9.
Operational stability of PAL-CLEAs and MSG-CLEAs.
Figure 10.
The storage stability of free-PAL, PAL-CLEAs and MSG-CLEAs.
At different storage times, samples of immobilized enzyme stored in 0.1 M phosphate buffer (pH 7.0) without substrate at 25°C were withdrawn and assayed for activity by described in the experimental section. The enzymatic activity which corresponds to 100% activity is 0.36 U/g and 0.43 U/g wet derivative for the CLEAs and MSG-CLEAs, and 1.3 U/g for the soluble enzyme.