Polysaccharides of tropical pasture herbage. IV. A pectic acid from Townsville lucerne ( Stylosanthes humilis )

Pectic acid, extracted from the stems of Townsville lucerne in 4% yield, has been fractionated by precipitation with sodium acetate. The product contains two components as revealed by electrophoresis in phosphate buffer, but the major structural characteristics have been determined by partial hydrolysis. The pectic acid is esterified to a very small extent (1% OCH3) and consists predominantly of 1,4-a-linked D-galacturonic acid units with L-arabofuranose units as the major neutral constituent.