[2)-alpha-L-Rhap3/4Ac-(1->] residue
[2)-alpha-l-rhap3/4ac-(1->] residue
A monosaccharide residue obtained formally by removal of the anomeric hydroxy group and the hydrogen attached to the 2-oxygen of <small>L</small>-rhamnopyranose in which either the 3- or 4-hydroxy group is acetylated.  The structure provided is representative of that found as the 3/4-<em>O</em>-acetylated Rha<small><sup>III</small></sup> epitope in <em>Shigella flexneri</em> strain 51251 and shows the acetylation at O-3, the more common site.