DESIGN OF CANDIDA ANTARCTICA LIPASE B THERMOSTABILITY IMPROVEMENT BY INTRODUCING EXTRA DISULFIDE BOND INTO THE ENZYME
Usman Sumo Friend Tambunan, Ahmad Randy and Arli Aditya Parikesit
DOI : 10.3844/ojbsci.2014.108.118
OnLine Journal of Biological Sciences
Volume 14, Issue 2
Candida Antarctica Lipase B (CALB) is extensively studied in enzymatic production of biodiesel, pharmaceutical products, detergents and other chemicals. One drawback of using CALB is its relatively low optimum temperature at 313 K (40Â°C). The objective of this research is to design CALB mutant with improved thermostability by introducing extra disulfide bond. Molecular dynamic simulation was conducted to get better insight into the process of thermal denaturation or unfolding in CALB. Thermal denaturation of CALB was accelerated by conducting simulation at high temperature. Molecular dynamic simulation of CALB was performed with GROMACS software package at 300-700 K. Prediction of possible mutation was done using "Disulfide by DesignTM" software. Selection of mutated residues was based on flexibility analysis of CALB. From those analyses, three mutants were designed, which are Mutant-1 (73LeuCys/151AlaCys), Mutant-2 (155TrpCys/294GluCys) and Mutant-3 (43ThrCys/67SerCys). Parameters that were used to compare the thermostability of mutant with wild type enzyme were Root Mean Square Deviations (RMSD), Solvent Accessible Surface Area (SASA), Radius of gyration (Rg) and secondary structure. Molecular dynamic simulation conducted on those three mutants showed that Mutant-1 has better thermostability compared to wild type CALB. We proposed the order of mutant thermostability improvement as follows: Mutant-1, Mutant-2 and Mutant-3, with Mutant-1 having better potential thermostability improvement and Mutant-3, the least stable.
© 2014 Usman Sumo Friend Tambunan, Ahmad Randy and Arli Aditya Parikesit. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.