Improved optimum temperature and thermostability of the lipase from Rhizopus chinensis CCTCC M201021 by site-directed mutagenesis of D190V

Abstract:

[Objective] D190V mutation was introduced into the lipase from Rhizopus chinensis CCTCC M201021 by site-directed mutagenesis to improve its optimum temperature and the thermostability. [Methods] The mutant lipase D190V and wild-type lipase r27RCL were expressed in Pichia pastoris and the enzymatic properties were characterized. [Results] The optimum temperature of D190V was 5 °C higher than that of the wild-type, and the half-life (T1/2) of D190V at 65 °C exceeded that of r27RCL by 1-fold, other enzymatic properties were similar to r27RCL. [Conclusion] According to the analysis of structures, the reason of improved thermostability for the variant by only an amino acid substitution D190V was probably due to the improved stability of the α-helix located and the strengthened hydrogen bonding force in the protein structure.

Key words:Site-directed mutagenesis, Rhizopus chinensis lipase, Optimum temperature, Thermostability