Immobilized enzymes comparison with soluble

Figure 5 illustrates the performance of immobilized cellulase in comparison with that of soluble cellulase. The small difference between the "crude" and "used" Spezyme CP profiles illustrates the very low uptake of soluble cellulase onto the support. Furthermore, soluble cellulase is much more active the dose of soluble enzyme is approx one-twentieth that of immobilized cellulase, once enzyme uptake is taken into account. Nonetheless, it is important to note that the immobilized enzyme is able to hydrolyze this insoluble substrate, albeit at a much lower rate. 

Fig. 5. Comparison of cellulose hydrolysis with soluble and immobilized cellulase. "Crude" and "Used" designations refer to the soluble enzyme collected before and after immobilization, respectively. CP, Spezyme CP.

Immobilized cellulase and amylase are able to hydrolyze cellulose and starch. However, the immobilized enzymes possess only about 1-6% of the activity of the soluble forms. In addition, immobilization clearly enhanced the thermal stability of amylase. Immobilized amylase retained more than half of its activity, even after incubation at 125°C. By comparison, soluble amylase was almost completely inactivated under these conditions. Furthermore, kinetics modeling indicates that the susceptibility to product inhibition is dependent on the amylase source. Finally, immobilization can reduce the susceptibility to product inhibition fQ was less for each of the immobilized forms, compared with their soluble counterparts. 

The thermal stability at 60 °C of CALB-7A was significantly higher than that of the soluble enzyme, with a stabilization factor of 92.15 (Table 2). In a previous study [27], when CALB was immobilized on coconut fiber by covalent attachment at pH 7 and 10, the immobilized enzyme was, respectively, 67- or 364-fold more stable than the soluble enzyme. Making a comparison between the thermal stabilization achieved by adsorption and covalent immobilization, it can be observed that the forces involved in immobilization of CALB on coconut fiber by adsorption are stronger than the bind between enzyme and support, formed dining immobilization by covalent attachment at pH 7. Nevertheless, it is not stronger than the interaction that occurred at pH 10. Other authors [9], when immobilizing CALB by adsorption in octyl silica, obtained a biocatalyst with half-life of around 2 h, which is less stable than CALB-7A prepared in this work (t /2= 8.92 h). 

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