Structural Modelling and in-silico characterization of a Novel Thermophilic β-amylase from Clostridium thermosulfuregenes

Abstract

β-amylase is a hydrolytic enzyme that is involved in breaking down starch and producing energy. Since the discovery of β-amylase, it has been applied in various applications especially in the food industry. In this study, a novel β-amylase from Clostridium thermosuluregen, a thermophilic anaerobic bacterium that ferments its extracellular emulsion to ethanol at 62 ℃ was modelled and studied using bioinformatics tools and compared with B. cereus β-amylases that functions at mesophilic conditions. The results showed that the overall structural conformations, secondary structures, and important residues involved in active and binding sites were identified in both proteins. The results revealed that the modelled β-amylase of C. thermosulfuregen is very similar with respect to the global conformation, location of active and binding sites. Both proteins showed identical structural domains with the thermophilic variant possessing a high percentage of hydrophobic amino acid residues, polar amino acid residues, and differences in secondary composition such as loops and beta sheets as the potential evolutionary thermal adaptations that make it stable enzyme that functions up to 70 ℃. The results suggest that the thermal stability are not dependent on one single unique mechanism and may use one or a combination of the mechanisms to sustain its structural conformation at a higher operating temperature. Overall, considering the common properties of this modelled protein with the β-amylase of B. cereus, it can be assumed that if the β-amylase of C. thermosulfuregen were expressed in-vitro, it would produce a stable protein that possesses the hydrolysis function for C. thermosulfuregen to break down the starch and sugar formation.