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Cyclodextrin dimers as receptor molecules for steroid sensors
M R de Jong1, J F Engbersen, J Huskens
1Laboratory of Supramolecular Chemistry and Technology, MESA+ Research Institute, University of Twente, Enschede, The Netherlands.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|December 29, 2000
Summary
Dansyl-modified cyclodextrin dimers show enhanced binding with specific steroidal bile salts, forming 1:1 complexes. The dansyl group influences binding, with minimal self-inclusion observed, confirmed by fluorescence studies.
Area of Science:
- Supramolecular Chemistry
- Host-Guest Chemistry
Background:
- Cyclodextrins are cyclic oligosaccharides known for their ability to form inclusion complexes.
- Modified cyclodextrins, such as dansyl-appended dimers, offer unique binding properties.
- Steroidal bile salts are important biological molecules with amphipathic properties.
Purpose of the Study:
- To investigate the binding interactions between a dansyl-modified cyclodextrin dimer and various steroidal bile salts.
- To determine the stoichiometry and stability of the formed complexes.
- To elucidate the role of the dansyl moiety and hydroxyl groups in the binding process.
Main Methods:
- Synthesis of a dansyl-modified cyclodextrin dimer (9) and a control dimer (6).
- Complexation studies with steroidal bile salts (cholate, deoxycholate, and others).
- Spectroscopic techniques, including fluorescence spectroscopy, to analyze binding and microenvironment.
Main Results:
- Dansyl-modified dimer 9 exhibits strong complexation with steroidal bile salts, particularly cholate and deoxycholate, in a 1:1 ratio.
- Binding enhancement is observed for cholate and deoxycholate compared to native beta-cyclodextrin.
- The dansyl moiety hinders cooperative binding, and minimal self-inclusion occurs, indicated by fluorescence data showing a polar microenvironment.
Conclusions:
- The dansyl-modified cyclodextrin dimer demonstrates selective and enhanced binding towards specific bile salts.
- The 12-hydroxy group's presence influences complex stoichiometry and stability.
- Fluorescence studies confirm the dansyl group's role and the formation of a polar binding pocket.