Structural Analysis of Glycopeptides and Glycoproteins Containing O-Glycosyl Linkages

Structural Analysis of Glycopeptides and Glycoproteins Containing O-Glycosyl Linkages 

In the past few years, two research groups, as well as a few others, have published several papers dealing with 13C-n.m.r.-spectral studies of sim- 

Chemical-shift Data for Various a- and /i-D-Clycosyl-L-threonine Derivatives 

On the other hand, resonance assignments for CP of threonine and serine, and C and Cy of hydroxy proline, were difficult to make, because of their proximity to carbohydrate carbon resonances. In most cases then, the resonances were assigned on the basis of the effects of pH on the chemical shifts of those resonances. It was shown that the chemical shifts for the carbohydrate carbon resonances were virtually unaffected (AS 0.4 p.p.m.) when going from the cationic state (pH 2) to the anionic state (pH 11) of the amino acid residues. The chemical shifts of C and CP of the amino acid residues, however, shifted considerably (up to 3.1 and 6.6 p.p.m. for C and CP, respectively see Table VI). 

In the literature, the anomeric configuration of the carbohydrates has usually been deduced from the C-l chemical-shift and from the spectral pattern, if observable. Because relevant model compounds were not previously available for providing C-l chemical-shift data for glycopep- 

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