title: On the impossibility of determination of stepwise binding constants for the 1 : 2 complex of (+)-camphor with alpha-cyclodextrin.
abstract: Knowledge of stepwise binding constants for complexes with higher than 1:1 stoichiometry would allow one to study the cooperativity of their formation. However, a detailed analysis of partitioning of the overall binding constant beta 12 determined by NMR titrations for the 1:2 complex of (+)-camphor with alpha-cyclodextrin into the stepwise ones K1 and K2 carried out analogously to published procedures revealed that the partitioning cannot be carried out unequivocally for K1 << K2. The programs for partitioning cannot be used as a black box and a satisfactory reproduction of the experimental dependence of relative shifts as a function of relative CD concentration should not be the only criterion of the reliability of the stepwise binding constants obtained using such programs.
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland. dodziuk@ichf.edu.pl
authors.forename: Helena
authors.initials: H
authors.lastname: Dodziuk
authors.forename: Krzysztof S
authors.initials: KS
authors.lastname: Nowinski
authors.forename: Wiktor
authors.initials: W
authors.lastname: Kozminski
authors.forename: Grigory
authors.initials: G
authors.lastname: Dolgonos
mesh_terms: D002164:Camphor / Q000737:chemistry* / Q000378:metabolism; D003505:Cyclodextrins / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D017186:Titrimetry; D047391:alpha-Cyclodextrins
chemical_list: D003505:Cyclodextrins; D047391:alpha-Cyclodextrins; D002164:Camphor; C032613:alpha-cyclodextrin