Molecular dynamics insights into pulsed electric field-induced structural and functional changes in polygalacturonase.

Pulsed electric field (PEF) is one of the emerging non-thermal sterilization technologies which can be applied to fruit juice preservation. The PEF process can also affect the activity and structure of enzymes and other natural macromolecules in fruit juice, including polygalacturonase (PG), an undesired enzyme which can dissolve the turbidity state of juice. However, the precise molecular mechanisms driving this phenomenon remain elusive. In this study, molecular dynamics simulations were used to investigate the effects of PEF on PG. It was found that with electric field strength <1 V/nm, the structural change of the protein is insignificant and could be restored within a few nanoseconds. However, with electric field strength >1 V/nm, most of the secondary structure is lost, the internal hydrogen bonds are broken and the hydrophobic core is exposed irreversibly. The relative positions of the active sites of the PG are also changed. The experimental results also showed that the activity of PG decreased with the increase of electric field strength. This study reveals the basic mechanism of the interaction between PEF and PG, suggesting PEF can potentially be used for enzyme control in fruit juice preservation.