Solution conformation of .alpha.-D-(1-3)- and .alpha.-D-(1-6)-linked oligomannosides using proton nuclear magnetic resonance

Abstract

The solution conformations of synthetic methyl mannobiosides and a methyl mannotrioside containing alpha D(1-3) and alpha D(1-6) linkages have been determined through the use of 1H nuclear magnetic resonance techniques, namely, the nuclear Overhauser effect and proton relaxation time measurements. 3J(C,H) coupling constants, obtained from a compound enriched with 13C, were also used. The allowed conformations were found to be in agreement with those determined from potential energy calculations and crystal structures. The methyl mannotrioside is an analogue of a mannotriose unit which occurs naturally in the "core" of asparagine-linked glycopeptides and in an "arm" of high mannose N-linked glycopeptides.