472466 Improving the Activity of a Thermophilic Lipase By Increasing the Flexibility Proximal to the Active Site
The thermodynamic parameters of reactions catalyzed by psychrophilic enzymes show that they are characterized by either lower transition state free energy values or smaller temperature dependence of activity than their thermophilic counterparts. The latter is achieved by the disruption of fewer enthalpy-driven interactions during the activation process. Therefore, localized increases in flexibility near the active site are responsible for the higher catalytic reaction rates of psychrophiles. Recently, the cold-activity of some thermophilic enzymes has been improved successfully by incorporating the structural elements of their psychrophilic counterparts, which shows that cold activity and thermostability are not mutually exclusive. In this study, we use site directed mutagenesis to increase the flexibility proximal to the active sites of lipase from Geobacillus thermocatenulatus by analysis of lipase from psychrophilic Photobacterium lipolyticum. Additionally, we compare the thermostability and kinetic parameters between the wild type lipase and the mutated one. In our talk, we will present these results discussing the structural differences and how the activity of thermophilic enzyme is affected.