title: Effects of pulsed electric fields on the activity and structure of pepsin.
abstract: A continuous pulsed electric field (PEF) system integrated with six co-field flow PEF treatment chambers was used to study the inactivation of pepsin. The inactivation of pepsin activity was a function of applied electric field strength, electrical conductivity, and pH. The inactivation of pepsin by PEF followed a first-order model. The first-order inactivation kinetic constant of pepsin was 0.012 (1/mus) in 7.5 mM HCl (pH 2.0) at 34.2 kV/cm. Aggregation of pepsin was observed during PEF treatment; however, the inactivation took place before the formation of aggregates. Circular dichroism analysis showed that inactivation of pepsin by PEF was correlated to the loss of beta-sheet structure in a pepsin molecule. The relative residual activity of PEF-treated pepsin was correlated to the relative molar ellipticity at 215 nm. Both PEF- and heat-induced inactivation of pepsin were correlated with the alteration of the secondary structure (beta-sheet dominant structure) of pepsin.
authors.affiliation: Department of Food Science and Technology, 2015 Fyffe Road, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Ruijin
authors.initials: R
authors.lastname: Yang
authors.forename: Si-Quan
authors.initials: SQ
authors.lastname: Li
authors.forename: Q Howard
authors.initials: QH
authors.lastname: Zhang
mesh_terms: D002942:Circular Dichroism; D004553:Electric Conductivity; D004560:Electricity; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010434:Pepsin A / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012995:Solubility; D012996:Solutions
chemical_list: D012996:Solutions; D010434:Pepsin A