PROTEASES FROM CELL CULTURE OF Bromelia hemisphaerica ...
PROTEASES FROM CELL CULTURE OF Bromelia hemisphaerica ...
PROTEASES FROM CELL CULTURE OF Bromelia hemisphaerica ...
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FSB1 – 2004<br />
Food Science and Biotechnology in Developing Countries<br />
V (U cm -3 )<br />
6<br />
5<br />
4<br />
3<br />
2<br />
1<br />
0<br />
Free<br />
0.0 0.5 1.0 1.5<br />
Figure 1. Initial rate vs. substrate concentration plots for glucose oxidase free<br />
and entrapped in liposomes.<br />
The decrease in the Vmax value caused by microencapsulation is considered to result<br />
from the lipid membrane, which can offer significant resistance to the transport of<br />
substrates. Therefore, the microencapsulation procedure limited accessibility of<br />
glucose molecules to the active sites of the enzyme and caused a decrease in the<br />
maximum reaction rate.<br />
1.0<br />
0.8<br />
0.6<br />
0.4<br />
0.2<br />
0.0<br />
Liposome<br />
0.0 0.5 1.0 1.5<br />
Cs (mol dm -3 ) Cs (mol dm -3 )<br />
Differences in the activity of free and liposomal glucose oxidase as a function of pH<br />
and temperature were investigated. Figure 2 indicates that pH and temperature<br />
promote different behaviour in the native enzyme in comparison with the entrapped<br />
one. Thus, native enzyme exhibits a maximum at pH 6.5 and 25ºC while liposomal<br />
enzyme shows a maximum a pH 5.2 and 26ºC. In the case of entrapped glucose<br />
oxidase, the effect of the temperature is more important to acid values of pH.
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