Molecular-Simulation-Assisted Immobilization and Catalytic Performance of CC Hydrolase MfphA on SBA-15 Mesoporous Silica

A molecular simulation strategy based on homology modeling and electrostatic potential calculations has been proposed to assist the immobilization process of a CC hydrolase MfphA onto mesoporous SBA-15. The size of the enzyme, pH-dependence of the immobilization process, and possible orientation of MfphA onto mesoporous materials (MPs) were predicted by molecular simulation. The adsorption of MfphA onto SBA-15 reached equilibrium in 1.5 hours at pH 7.0 and the maximum loading capacity was 34 mg g−1. Meanwhile at pH 9.0, no obvious adsorption was observed after 12 hours which corresponded to the molecular simulation prediction. It was also shown that, after immobilization, the catalytic activity of immobilized MfphA decreased to some extent, but the thermal stability was significantly improved. Guanidinium chloride (GdmCl) exhibited similar activity attenuation for both immobilized and free enzyme. By contrast, the immobilized MfphA was more resistant to urea at high concentration than was the free enzyme. Meanwhile, recycling experiments showed that the immobilized enzyme retained 30 % of its initial activity after ten reaction cycles.