Insight into the mechanism behind the activation phenomenon of lipase from Thermus thermophilus HB8 in polar organic solvents

Publication date: Available online 8 March 2017 Source:Journal of Molecular Catalysis B: Enzymatic Author(s): Hao Cao, Kaili Nie, Haijun Xu, Xin Xiong, Rumen Krastev, Fang Wang, Tianwei Tan, Luo Liu A thermophilic lipase from Thermus thermophilus (lipaseTt) was heterologously overexpressed in Escherichia coli BL21(DE3). The tolerance of (lipaseTt) towards polar organic solvents and the associated activation phenomena were investigated. The catalytic efficiency (Kcat/KM) of lipaseTt in 56% DMSO was up to 25.64 times higher than that in phosphate buffer. Molecular dynamic (MD) simulations were carried out to investigate the activation mechanism of the lipaseTt by polar organic solvents. After refining the homology modeling of lipaseTt by using MD-simulation, a new secondary structure in the lid region indicates a rigid structure, corresponding to its nature of thermostability. Subsequently, the loss of a secondary structure of lipaseTt in the presence of polar organic solvent was observed in both MD-simulation and Circular dichroism spectra. The results of MD-simulation demonstrate that the overall structure maintained stable with or without polar organic solvent; however, the lid region was found more flexible in the presence of polar organic solvent. The flexible lid facilitates the substrate to access the catalytic site inside the lipase and the lipase displays enhanced activity in the presence of a polar organic solvent. Graphical abstract
Source: Journal of Molecular Catalysis B: Enzymatic - Category: Biochemistry Source Type: research