Thermodynamic parameters and stoichiometries for the binding of anilinonaphthalenesulfonates to beta-cyclodextrin are obtained from steady-state fluorescence intensity and anisotropy measurements. Specifically, formation constant, enthalpy, and entropy values are obtained for complexes of beta-cyclodextrin with eight different substrate molecules at five different temperatures and six different pH values, and their associated errors are given. We propose an explanation of the relative magnitudes of the values obtained with regard to the geometry of the substrate and the importance of the various noncovalent interactions responsible for the complexation.

Thermodynamic study on the effects of beta-cyclodextrin inclusion with anilinonaphthalenesulfonates.

Hydrogen bonding and conformation of glucose and polyglucoses in dimethyl-sulphoxide solution

The anomeric proton (H-1) chemical shifts of D-mannopyranosides in aqueous solution are affected both by the aglycon and by substitution of the ring [Lee, Y. C., & Ballou, C. E. (1965) Biochemistry 4, 257]. We have examined the 1H NMR spectra for a variety of linear and branched mannooligosaccharides and have assigned the H-1 resonances to the component sugars. The chemical shifts, which range from delta 4.76 to 5.36, provide information regarding the linkages, sequences, and anomeric configurations of mannose residues in an oligomer. Thus, 1H NMR spectroscopy can complement enzymatic hydrolysis, methylation analysis, and acetolysis for the structural characterization of oligosaccharides. Furthermore, small structural differences between otherwise identical oligosaccharides are often accompanied by long-range chemical shift changes for the anomeric protons. Because sugars three or more residues away from the structural alteration can be affected, the changes must reflect conformational differences. We have placed emphasis on the mannose-rich oligosaccharides from glycoproteins, particularly those produced by endo-beta-N-acetylglucosaminidase digestion. Two mannose-rich glycopeptides were isolated from a monoclonal human IgM and their positions of origin on the polypeptide chain were determined. The oligosaccharides were released with endo-beta-N-acetylglucosaminidase and fractionated into several size classes. Our structural studies show that each glycopeptide possessed a unique set of oligosaccharides, in agreement with a recent report [Chapman, A. & Kornfeld, R. (1979) J. Biol. Chem. 254, 816]. The NMR spectra were particularly valuable in detecting and quantitating isomeric fragments not observed previously, and our results suggest a modification of the scheme presented by Chapman and Kornfeld for the processing of mannose-rich IgM oligosaccharides.

Linkage and sequence analysis of mannose-rich glycoprotein core oligosaccharides by proton nuclear magnetic resonance spectroscopy.

Conformation of O-methylated amylose and cyclodextrins☆

From scale models of the cyclodextrins it would appear that the primary hydroxyl groups (one per glucose unit; all glucose units c~1-+4 linked [3]) always line the outer brim irrespective of the conformation [7]. If all the glucose residues in cyclodextrins are present in the C -1 chair form [9] as NMR studies indicate [8], the CH-groups of carbons 3 and 5 of each unit and less prominently the glycosidic oxygen would form the inside of the ring [4 I. Therefore, the void space should be relatively hydrophobic. In aqueous solution each individual cyclodextrin molecule is surrounded by solvating water which in principle can be of two different types:

Inclusion Compounds of Cyclodextrins

The proton magnetic resonance spectra of carbohydrates in deuterium oxide solution were obtained and considered with respect to probable conformation. The anomeric proton signal occurred at lowest field and was easily recognized. In the various glucose derivatives investigated, this signal occurred from 4.62 to 5.25 τ for equatorial protons and from 5.12 to 5.65 τ for axial protons. Within each of these ranges, the chemical shifts varied inversely with the electronegativity at the C1 site, as calculated by the technique of Gordy (1). Variable electronegativity at C1 accounts for the overlap of ranges for equatorial and axial protons, thereby bringing the n.m.r. data into agreement with assignment of the C1 chair form of the pyranose ring to the linear polymers of D-glucopyranose. The orientation of the glucopyranose rings in cyclodextrins is shown to preclude ring current effects, and the up-field chemical shifts of these materials are shown to be consistent with the C1 form.

C. A. Glass

Papers

Proton magnetic resonance spectra of d-glucopyranose polymers