Investigation on the structure and function of porcine pancreatic elastase (PPE) under the influence of putrescine: A spectroscopy and molecular simulation study

Abstract

The growing use of enzymes in various industries has created the need to study their interactions with different ligands. In this study, structural changes and the activity of elastase in the presence of putrescine were investigated. For this purpose, we used various techniques such as UV–vis spectrophotometry, spectrofluorometry and circular dichroism, as well as molecular docking and molecular simulation. This work was performed at three temperatures of 303, 313 and 323 K, with the pH of 8.5 (Tris buffer). Increased absorption in the UV–vis spectrophotometry results suggested a change in the environment of tryptophan. The emission intensity of elastase was decreased to a large extent, and the static quenching was proved. The entropy and enthalpy values indicated that the bond between elastase and putrescine consisted of van der Waals forces or hydrogen bonding. The values of Vmax (kcat [E]) and Km of elastase- putrescine rather than elastase were increased. A very slight alteration in the second structure of elastase (10.5% increase for α-helix and 2.0% decrease for β-sheet) was observed and Tm increases from 332.8 for the native elastase to 335.3 K for elastase-putrescine.