Effects of proanthocyanidins on porcine pancreatic lipase: Conformation, activity, kinetics and thermodynamics

The interactions between proanthocyanidins (PC) and porcine pancreatic lipase (PL) were investigated from variant aspects of lipase conformation, activity, kinetics, and thermodynamics. Results show that 34% inhibitory rate of PC on PL is achieved after about 30-min incubation, and the inhibitory rate increases with the increase of PC concentration and then plateaus at the PC/PL ratio of 200. Circular dichroism and fluorescence spectroscopic analyses demonstrate that PC decreases the alpha-helix content while increases the beta-sheet content of PL, but does not change the microenvironment of Trp, and PC quenches the fluorescence of PL both dynamically and statically through the formation of PL-PC complex. PC induces PL aggregation and then stabilizes the lipase aggregates. Kinetic studies reveal that PC does not change the K-m value while decreases the V-max value, implying that PC non-competitively inhibits the PL activity. (c) 2013 Elsevier Ltd. All rights reserved.