Molecular dynamic simulation studies of bacterial thermostable mannanase unwinding the enzymatic catalysis

β-Mannanase is a hemicellulolytic endohydrolase that catalyzes the random hydrolysis of β-D-1,4-mannosidic linkages in main chain of mannans. Thermostable mannanase has a potential application in various pulp and food industries. However till date scarcely any result is reported regarding their stability in comparison to other proteins. In this work molecular dynamics simulation analysis was performed to check the tenacity of docked complexes at a different temperature to explore that active site of enzyme was occupied with substrate throughout the simulation only at their optimum temperature (338 K). The persistence of average hydrogen fusion between enzyme and substrate by the key amino acids (Asp, Glu, Tyr) are the main factor for activity and stability at high temperature. The loss of key amino acids and backbone hydrogen bonds decreased incrementally with temperature other than optimum (338 K) in all simulations, probing structural changes associated with enthalpy-entropy compensation. Stability of these complexes was extensively analyzed on the basis of binding energy that disclosed substantial tenacity of enzyme substrate complex at optimum temperature. The overall data provided better understanding of these factors which usually affect enzyme activity/stability at high temperature as well as suggested approaches to bioengineer these industrially important enzymes to enhance their thermostability.