Improving enzyme immobilization in mesocellular siliceous foams by microwave irradiation

https://doi.org/10.1263/jbb.106.286Get rights and content

Microwave irradiation was used to immobilize papain and penicillin acylase in mesocellular siliceous foams (MCFs) at low temperature. The maximum loading of papain reached 984.1 mg/g, 1.26 times that obtained using the conventional, non-microwave-assisted method. The half-life (t0.5) of papain immobilized in MCFs by microwave irradiation at 80°C was 17 h, 5.21 times that of papain immobilized by conventional means. The activities of papain and penicillin acylase immobilized with the microwave-assisted method were 779.6 U/mg and 141.8 U/mg respectively, 1.86 and 1.39 times of those obtained without microwave immobilization. Using microwave irradiation it only took 140 s for penicillin acylase, an enzyme of large dimensions, to be immobilized in MCFs. In contrast, it took 15 h to do the same using the conventional method. The results showed that microwave irradiation improved the adsorption and immobilization of enzymes in mesocellular siliceous foams.

Section snippets

Materials

Penicillin acylase (EC 3.5.1.11, 796 U/ml, 10 mg/ml) from Bacillus megaterium, was obtained from Zhejiang Shunfenghaidier (Dongyang, P.R. China). Penicillin G potassium was from Hua Xing Medicines Factory (Xinxiang, P.R. China). Papain (EC 3.4.22.2, 1196.4 U/mg) was purchased from Guangxi Pangbo Biotechnology (Nanning, P.R. China). Poly (ethylene glycol)-poly-block (propyleneglycol)-poly-block (ethylene glycol) (P123) was from Sigma-Aldrich of the highest grade commercially available. Other

Characterization of the support

The nitrogen adsorption-desorption isotherms and pore size distribution are shown in Fig. 1. The data indicated that uniformly sized and large spherical cells were interconnected by uniform windows and could form a continuous 3-D pore system. This result showed that the structure of MCFs was retained during microwave digestion of the organic templates.

Effect of microwave power output level on the activity of the immobilized enzyme

In organic syntheses, microwave irradiation can accelerate organic transformation and reduce reaction times from days and hours to minutes and

Acknowledgments

This work was supported by The National High Technology Research and Development Program of China (863 Program, no. 2006AA02Z211), The National Natural Science Foundation of China (20376034), The Natural Science Foundation of Jiangsu Province of China (BK2006181), and The Foundation of Jiangsu Province of China for College Postgraduate Students in Innovation Engineering (2007). We thank Shayne X. Wang, Ph.D. for revising the manuscript.

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