Circular dichroism readout of sugar recognition in the cleft of a fused-pyridine receptor.
Dicarboxamide host 2 forms 1:1 complexes with n-octyl pyranosides derived from D-glucose, D-mannose, D-galactose, D-fucose, D-lyxose, and D-arabinose. Association constants (K(a)) in the range of 77-940 M(-1) were measured in chloroform by means of induced circular dichroism and fluorescence spectroscopy. Variations in K(a) values correspond qualitatively to expected differences in hydrogen-bonding abilities of guest hydroxyl groups. Induced circular dichroism effects for complexes of saccharides bearing equatorial 3-OH, 4-OH, and 6-OH groups show that the host chromophore is twisted in a P-helical conformation. A structural model is proposed that is also consistent with the results of previous studies involving complexation of dicarboxylic acid 1 with cationic saccharides in methanol.
Tamaru
Shun-ichi
S
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan.
Shinkai
Seiji
S
Khasanov
Alisher B
AB
Bell
Thomas W
TW
D000838:Anions; D002241:Carbohydrates / Q000737:chemistry*; D002412:Cations; D002942:Circular Dichroism; D003998:Dicarboxylic Acids / Q000737:chemistry; D005944:Glucosamine / Q000737:chemistry; D006860:Hydrogen Bonding; D007700:Kinetics; D000432:Methanol / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D011485:Protein Binding; D011725:Pyridines / Q000737:chemistry*; D012263:Ribonucleosides / Q000737:chemistry; D013050:Spectrometry, Fluorescence
D000838:Anions; D002241:Carbohydrates; D002412:Cations; D003998:Dicarboxylic Acids; D011725:Pyridines; D012263:Ribonucleosides; D005944:Glucosamine; C023666:pyridine; D000432:Methanol