Catalytic properties of 2,3-dihydroxybiphenyl 1,2-dioxygenase from Dyella Ginsengisoli LA-4 immobilized on mesoporous silica SBA-15

• Molecular simulation approach predicted the interaction of 2,3-dihydroxybiphenyl 1,2-dioxygenase and SBA-15 at different pH.
• Thermostability, store stability and reusability of 2,3-dihydroxybiphenyl 1,2-dioxygenase were greatly improved by immobilization.
• Improvement of 2,3-dihydroxybiphenyl 1,2-dioxygenase stability was correlated to the alteration of its secondary structure.

In this study, 2,3-dihydroxybiphenyl 1,2-dioxygenase (BphC) from Dyella ginsengisoli LA-4 was immobilized on the mesoporous silica SBA-15 in order to improve its stability with relatively high retaining activities. By Fourier transformed infrared spectroscopy (FTIR) and N2 adsorption/desorption isotherms, BphC was confirmed to be successfully adsorbed and captured on SBA-15. Under the experimental conditions, the maximum loading amount could reach 124.6 mg protein g−1 support. The immobilized BphC could keep 16% of its initial activity after being stored at 4 °C for 5 days, whereas the free enzyme lost its activity rapidly within 12 h. Furthermore, the immobilized BphC possessed 90% of its initial activity after incubating at 40 °C for 4 h, indicating that the thermostability of BphC was significantly improved by immobilization. The biodegradation of catecholics compounds has been studied by immobilized BphC in batch system. The enhanced properties of immobilized BphC were further analyzed by the circular dichroism (CD), which supposed that the activity and stability alteration was due to the changes of secondary structure of BphC. This study would contribute to realizing the more effective biodegradation and bioremediation processes by immobilizing enzymes on the mesoporous silica materials.

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