Modulation with acetonitrile of the dynamics of guest binding to the two distinct binding sites of cholate aggregates.
Bile salt aggregates are supramolecular systems containing two different binding sites. The effect of the addition of acetonitrile on the specificity and dynamics of guest binding to the two binding sites of cholate aggregates was studied. The protection of guests included in the aggregate from interaction with ions in the aqueous phase was evaluated from quenching of the singlet and triplet excited states of guest molecules bound to the cholate aggregates. The dynamics of guest binding to the primary and secondary binding sites of the cholate aggregates were determined at increasing acetonitrile mole fractions. The structure of the aggregates was not significantly altered provided the cholate concentrations were higher than 20 mM and the acetonitrile mole fraction did not exceed 0.033 (9.1% v/v). These results show that acetonitrile can be used to modulate the solubility of guests in the aggregates and to manipulate the residence time of guests in the primary and secondary binding sites.
Yihwa
Chang
C
Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6.
Quina
Frank H
FH
Bohne
Cornelia
C
D000097:Acetonitriles / Q000737:chemistry; D001647:Bile Acids and Salts / Q000737:chemistry; D001665:Binding Sites; D020355:Cholates / Q000737:chemistry*; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D012995:Solubility
D000097:Acetonitriles; D001647:Bile Acids and Salts; D020355:Cholates; D046911:Macromolecular Substances; C032159:acetonitrile