Molecular study of mucin-procyanidin interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR.
Astringency is closely related to the interaction between procyanidins and salivary proteins (SP). The aim of this work was to study the interaction between mucin, a SP responsible for saliva lubricating properties, with different procyanidins (B4 dimer, tetramer (TT) and fractions of oligomeric procyanidins), and the influence of several conditions [pH, ionic strength, procyanidins' mean degree of polymerization (mDP) and different solvents (ethanol or dimethylsulfoxide)] on this interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR. For fractions of oligomeric procyanidins, the mucin-procyanidin interaction increased with mDP; however, for pure compounds, procyanidin TT has lower affinity than dimer B4 which could be due to a lower structural flexibility imposed by its complex structure. Furthermore, EtOH and DMSO can disrupt the main driving forces of these interactions, hydrophobic interactions and hydrogen bonds, respectively, lowering significantly the binding constants.
REQUIMTE/LAQV, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre S-N, 4169-007 Porto, Portugal.
Elsa
E
Brandão
REQUIMTE/LAQV, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre S-N, 4169-007 Porto, Portugal.
Mafalda
M
Santos Silva
REQUIMTE/LAQV, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre S-N, 4169-007 Porto, Portugal.
Ignacio
I
García-Estévez
REQUIMTE/LAQV, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre S-N, 4169-007 Porto, Portugal.
Nuno
N
Mateus
REQUIMTE/LAQV, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre S-N, 4169-007 Porto, Portugal.
Victor
V
de Freitas
REQUIMTE/LAQV, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre S-N, 4169-007 Porto, Portugal. Electronic address: susana.soares@fc.up.pt.
Susana
S
Soares
D044946:Biflavonoids / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009077:Mucins / Q000737:chemistry*; D044945:Proanthocyanidins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
D044946:Biflavonoids; D009077:Mucins; D044945:Proanthocyanidins; C017674:procyanidin; D002392:Catechin
Dimethylsulfoxide; Ethanol; Mucin-procyanidin interaction; Procyanidin B4; Procyanidin tetramer