Fluorescence quenching of methyl-2-aminobenzoate in the presence of beta-cyclodextrin: A model for the dynamic quenching of chromophores in hydrophobic regions of biopolymers
✍ Scribed by Aart De Korte; Richard Langlois; Charles R. Cantor
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1980
- Tongue
- English
- Weight
- 399 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
The binding constant of methyl‐2‐aminobenzoate to beta‐cyclodextrin was determined by fluorescence titration to be 92.1__M__^−1^ at 25°C in pH 7 buffer. Beta‐cyclodextrin dramatically protects methyl‐2‐aminobenzoate against quenching by iodate and protects, though much less efficiently, against the smaller quencher, iodide. The observed decrease in fluorescence lifetime of the methyl‐2‐aminobenzoate‐beta‐cyclodextrin complex on addition of quencher indicates that the quenching mechanism is collisional (dynamic). The dependence of quenching rate on solvent viscosity is less than expected from simple theoretical considerations. However, the extent of beta‐cyclodextrin protection is essentially viscosity‐independent. These model studies show the usefulness of iodate as a quencher and encourage further attempts at quantitative interpretation of quenching studies on chromophores attached to biopolymers.