Modification of the solvent environment and increasing the thermal stability of Trypsin: Thermodynamic and docking studies

The crucial importance of enzymes in industry and medical applications stems from their stability and functional dimensions, making their study a subject of active research. The aim of this study was to try for increasing the thermal stability of trypsin by modification of the solvent environment. So, we study how sorbitol could effect on the conformation and thermal stability of trypsin. In this study, interaction of one polyol (sorbitol) with trypsin has been studied in vitro, under simulated physiological conditions by molecular docking and multi-spectroscopic techniques (thermal denaturation analysis, fluorescence spectroscopy, circular dichroism studies). We have determined the thermodynamic parameters, enthalpy change (∆H°), entropy change (∆S°) and Gibbs free energy change (∆G°), transition temperature (Tm) to understand trypsin stability. The results illustrate that sorbitol can bind to trypsin, forming xylitol-trypsin complexes, mainly via hydrogen bonding and Vander Waals forces. Sorbitol acted as enhancers for trypsin stability. Fluorescence spectroscopy revealed the static mode of the quenching. The number of binding sites was 1. Fluorescence spectroscopy and the molecular docking technique revealed that the hydrogen bonding and Vander Waals forces played a major role in stabilizing the complex. Tm of this complex was enhanced due to the higher H-bond formation and the lower surface hydrophobicity after sorbitol modification. The result shows that sorbitol can protect the native structural conformation of trypsin. These results explicitly describe that stabilizing sorbitol is preferentially excluded from the surface of trypsin, since water has a higher tendency toward favorable interactions with functional groups of trypsin than with sorbitol.