Molecular Dynamics Simulation Combined with Thermal Stability Experiments to Analyze the Interaction Mechanism between Acetylglucosamine and Lipase
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Abstract:
In this study, molecular dynamics simulation was used to examine the interaction between Candida Antarctica Lipase B (CaLB) and acetylglucosamine (GlcNAc), and demonstrate the protective effect of GlcNAc on CaLB through thermal stability experiments. The results show that at 323.15 K, the electrostatic potential energy of CaLB and GlcNAc as well as Lennard-Jones (L-J) decreased significantly in the first 20 ns simulation time. When the CaLB-250 mmol/L-GlcNAc model was at 0~100 ns, the electrostatic potential energy and LJ potential energy decreased by 3350 kJ/mol and 2791 kJ/mol, respectively, and the number of hydrogen bonds between them increased from 0 to about 115. The accessible area (SASA) of CaLB and GlcNAc is close to 50 nm2. The root mean square deviation (RMSD) and root mean square fluctuation (RMSF) data show that the RMSD of the Free-CaLB model at 323.15 K and 353.15 K were 0.2617 nm and 0.3473 nm, respectively, while the RMSF of the CaLB-GlcNAc model at different concentrations was smaller than that of Free-CaLB, and the fluctuation of the CaLB-GlcNAc assembly model region (Val 147-Leu 155) was significantly smaller than that of the Free-CaLB model, indicating that GlcNAc can weaken the toughness of Free-CaLB and maintain effectively the original structure of CaLB. Thermal stability experiments showed that: after Free-CaLB and CaLB-GlcNAc were treated at 60 ℃ for 2.0 h, the residual enzyme activity of Free-CaLB was only 22.26%, whilst the residual enzyme activity of CaLB-GlcNAc was 52.11%. In summary, the thermal stability of Free-CaLB can be improved by acetylglucosamine.
