Thermoanaerobacter tengcongensis esterase resists denaturation by urea and sodium dodecyl sulfate

Abstract

Introduction: The broad applications of lipolytic enzymes in various industrial processes have led to increased interest in esterases with distinctive features. Thermophiles are promising source of esterases with inherent thermal and chemical stability. Thermoanaerobacter tengcongensis esterase (TTE) is one of such esterases with thermostable potential, however, its resistance to protein denaturants, detergents and molecular docking studies are yet to be fully characterised. Aim: Therefore, this study investigated the in vitro and in silico effects of urea and sodium dodecyl sulfate on TTE activity. Experimental: TTE activity was determined spectrophotometrically at 405 nm. TTE was active over a pH range of 3.0 to 12.0 and its activity was optimal at alkaline range of 9.0 and 12.0. Results: TTE was found to be most active at 60 °C with the highest thermal stability at the same temperature. Urea at 0.1 to 4.0 mM had a concentration dependent activating effect on TTE; SDS (0.5 to 4.0 mM) had similar effect on the enzyme. Urea at 0.5, 1.0 and 2.0 mM increased maximum reaction rate (Vmax), catalytic constant (Kcat) and Michaelis constant (Km) of TTE. All concentrations of SDS (0.5 to 2.0 mM) investigated increased Vmax and Kcat, while the Km value of TTE reduced in the presence of 1.0 and 2.0 mM SDS. Structural characterization of TTE substantiates the in vitro thermostability claim. The molecular docking analysis revealed that donepezil demonstrated optimal binding with TTE. Conclusion: the findings from this study showed that TTE strongly resists denaturation by optimal concentrations of urea and SDS.