[2)-alpha-L-Rhap-(1->3)-alpha-L-Rhap-(1->3)-alpha-L-Rhap-(1->]n
[2)-alpha-l-rhap-(1->3)-alpha-l-rhap-(1->3)-alpha-l-rhap-(1->]n
A polysaccharide derivative comprising a trisaccharide repeating unit consisting of three α-<small>L</small>-rhamnosyl residues linked sequentially (1→3) and (1→3), with the trisaccharide repeats themselves being linked (1→2); a main component of <em>Pseudomonas aeruginosa</em> A-band polysaccharide (A-PS).