title: Mechanisms of tannin-induced trypsin inhibition: a molecular approach.
abstract: Association of procyanidins with enzymes has drawn attention over the past few years. This work aimed to bring insights on interaction of the protease trypsin with the procyanidin dimer (B3). This interaction was characterized by fluorescence quenching, saturation transfer difference (STD) NMR, molecular modeling, and through an enzymatic inhibition assay. Further studies were conducted regarding the influence of pectin on the binding process. A general overview of the binding process may be outlined as follows: a) at low procyanidin concentrations (below the critical micellar concentration-(CMC)) a specific interaction probably driven by hydrogen bonds between the protein backbone and the procyanidin occurs and is associated with the reduction of both enzyme activity and fluorescence; b) at high procyanidin concentration (above the CMC) the interaction becomes nonspecific. This variation in both nature and extent of the interaction with the variation of procyanidin concentration shows how tannin self-association may affect the interaction between tannins and proteins. It was also shown that the mechanism through which pectin affects the interaction between procyanidin B3 and trypsin is of a competitive type.
authors.affiliation: Centro de Investigação em Química, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
authors.forename: Rui
authors.initials: R
authors.lastname: Gonçalves
authors.forename: Nuno
authors.initials: N
authors.lastname: Mateus
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pianet
authors.forename: Michel
authors.initials: M
authors.lastname: Laguerre
authors.forename: Victor
authors.initials: V
authors.lastname: de Freitas
mesh_terms: D000818:Animals; D044946:Biflavonoids / Q000378:metabolism* / Q000494:pharmacology*; D002392:Catechin / Q000378:metabolism* / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D056004:Molecular Dynamics Simulation; D010368:Pectins / Q000378:metabolism; D044945:Proanthocyanidins / Q000378:metabolism* / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D014357:Trypsin / Q000737:chemistry / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D044946:Biflavonoids; D008823:Micelles; D044945:Proanthocyanidins; D014361:Trypsin Inhibitors; C479581:procyanidin B3; D010368:Pectins; D002392:Catechin; D014357:Trypsin