Abstract
The anomeric proton magnetic resonances of Mycobacterium smegmatis 3-O-methylmannose polysaccharide have chemical shifts intermediate betwen those of nonaglucoamylose and alpha-cyclodextrin, and on addition of palmitic acid most of these resonances are shifted upfield toward that of the cyclodextrin. This suggests that the methylated polysaccharide could have a conformation with some secondary structure intermediate between those of the two reference compounds, and that it forms a tightened coil upon addition of the lipid which yields an inclusion complex with the polysaccharide. The change in chemical shift is linear with lipid concentration, which indicates that the complex undergoes rapid exchange with free polysaccharide. The changes in proton chemical shifts of the polysaccharide and of the palmitic acid are consistent with the fatty acid being inserted in the coiled polysaccharide with its carboxyl group near the methyl aglycon.
Highlights
The anomeric proton magnetic resonances of Mycobacterium smegmatis 3-0-methylmannose polysaccharide have chemical shifts intermediate between those of nonaglucoamylose and cu-cyclodextrin, and on addition of palmitic acid most of these resonances are shifted upfield toward that of the cyclodextrin
Spectrum in the presence of an equimolar concentration of palmitic acid, which reveals that a majority of the anomeric proton signals are shifted upfield in the complex
The anomeric proton resonances of MMP-III serve as intrinsic probes of polysaccharide conformation when the chemical shift data for free MMP-III and its complex with palmitic acid are compared with those of reference al + 4-glucans
Summary
The anomeric proton magnetic resonances of Mycobacterium smegmatis 3-0-methylmannose polysaccharide have chemical shifts intermediate between those of nonaglucoamylose and cu-cyclodextrin, and on addition of palmitic acid most of these resonances are shifted upfield toward that of the cyclodextrin. This suggests that the methylated polysaccharide could have a conformation with some secondary structure intermediate between those of the two reference compounds, and that it forms a tightened coil upon addition of the lipid which yields an inclusion complex with the polysaccharide.
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