Improved activity of immobilized horseradish peroxidase on gold nanoparticles in the presence of bovine serum albumin
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The using of macromolecular additives is known to be a simple and effective way to improve the activity of immobilized enzymes on solid support, yet the mechanism has not been well understood. Taking horseradish peroxidase (HRP) as an example, only 30 % of its catalytic activity was kept after being immobilized on the surface of 25-nm Au nanoparticles, mainly attributed to the conformational change of the heme-containing active site. The catalytic activity of HRP was significantly improved to 80 % when a certain amount of bovine serum albumin (BSA) was added at the initial stage of the immobilization. Systematic spectral investigation indicated that the addition of BSA inhibited the tertiary structure change around the active site, which was a prerequisite for improved activity of the immobilized HRP. Steady-state kinetic analyses revealed that the introduction of BSA could effectively improve the turnover rate of substrate to product in spite of slight reduced affinity to substrates, which also contributed to the improved catalytic activity.
KeywordsEnzyme Catalytic activity Immobilization Horseradish peroxidase Bovine serum albumin Nanoparticle Nanobiotechnology
This work is supported by the National Research Fund for Fundamental Key Project (Nos. 2011CB935800, 2009CB939701) and the National Natural Science Foundation of China (Nos. 21073078 and 51072064). We are grateful to Prof. M. Y. Han for valuable discussion.
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