To evaluate the type of binding involved, thermodynamic analysis of the temperature dependence of proanthocyanidin binding to bovine serum albumin (BSA) and bean glycoprotein G-l (G-l) was investigated. Binding was analyzed with tritiated proanthocyanidin by ultrafiltration to separate free ligand and protein-bound ligand. Binding constants were determined from Scatchard plots. Van't Hoff plots indicated proanthocyanidin binding to BSA was spontaneous and entropy driven. Analysis with cis-parinaric acid supported the conclusion drawn from the thermodynamic analysis that the binding of proanthocyanidin to BSA was a hydrophobic interaction. Van't Hoff plots indicated proanthocyanidin binding to native G-l protein was also spontaneous but, in contrast to BSA, enthalpy driven. Analysis with cis-parinaric acid confirmed the hydrophilic character of proanthocyanidin binding to native G-l. Evaluation of proanthocyanidin binding to heat-denatured G-l with cis-parinaric acid indicated hydrophobic interactions.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)