One of the anti-complementary pectic polysaccharides (AR-2IIa) isolated from the root of Angelica acutiloba Kitagawa gives the "ramified" region (PG-la, rhamnogalacturonail with neutral side-chains) in addition to oligogalacturonides on digestion with endo-a-o-(l-+4)-polygalacturonase.
When the neutral sidechains in PG-la were digested with both exo-a-L-arabinofuranosidase and exo+Dgalactosidase, -70% of the arabinosyl chains and -30% of the galactosyl chains were released. The resistant product E-PG-la had the same anti-complementary activity as PG-la. E-PG-la gave long (d.p. 35) and short (d.p. ~4) neutral galactosyl chains after degradation of the GalA moiety by base-catalysed @elimination in the presence of sodium borodeuteride followed with lithium-mediated degradation. Methylation analysis showed that the long galactosyl chains consisted mainly of terminal, 6-linked and 3,6_disubstituted Gal, and that the short chains were rich in 6-linked Gal. Degradation of the GalA moieties in PG-la markedly decreased the anti-complementary activity, but the long and short galactosyl chains still expressed -50 and -20%) respectively, of the anti-complementary activity of E-PG-la. WTRODUCTION Four anti-complementary pectic polysaccharides (AR-211a-IId)2 isolated from the root of Angefica acutiloba Kitagawa consist of large proportions of polygalacturonan regions and small proportions of "ramified" regions. The anti-complementary activities of AR-2IIa-IId are expressed2 mainly by their "ramified" regions, the activities of which are regulated by the polygalacturonan regions. The "ramified" regions consist3 of rhamnogalacturonan cores with galactosyl and arabinosyl side-chains, some of which possess common structures and play a role in the expression of the anti-complementary activity. *Studies on Polysaccharides from A. acutiloba, Part XII. For Part XI, see ref. 1.