Photophysics of ANS. V. Decay modes of ANS in proteins: the IFABP-ANS complex.
The fluorescence properties of ANS as bound to proteins are treated. Several points of view concerning the origin of these properties are reviewed and synthesized into one framework. On proteins where the quantum yield (QY) is appreciable, as in organic solvents, the preferred conformation of ANS is often with the phenyl ring nearly (65 degrees -85 degrees ) orthogonal to the naphthalene. The major consequence of this geometry is water exclusion from the critical zone of ANS at which the largest amount of solvent dipolar relaxation originates. This, in turn, leads to a depression of the rate of electron transfer to the surroundings, together with other effects, as noted in the literature and in our lab. Alternative quenching pathways for ANS on the protein vs in water are also elucidated.
Kirk
William
W
Mayo Clinic College of Medicine, Rochester MN 55902, USA. kirk.william@mayo.edu
Kurian
Elizabeth
E
Wessels
William
W
D000817:Anilino Naphthalenesulfonates / Q000737:chemistry*; D001059:Apoproteins / Q000737:chemistry; D004579:Electron Transport; D050556:Fatty Acid-Binding Proteins / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D008968:Molecular Conformation; D009211:Myoglobin / Q000737:chemistry; D010777:Photochemistry; D055585:Physical Phenomena; D010825:Physics; D011485:Protein Binding; D011789:Quantum Theory
D000817:Anilino Naphthalenesulfonates; D001059:Apoproteins; D050556:Fatty Acid-Binding Proteins; D005456:Fluorescent Dyes; D009211:Myoglobin; C010857:apomyoglobin; C027132:1-anilino-8-naphthalenesulfonate