title: Relationship between structure and immunological activity of an arabinogalactan from Lycium ruthenicum.
abstract: An immunologically active arabinogalactan (LRGP3) was selectively degraded by acetolysis, mild acid hydrolysis and enzymatic digestion. After exo-α-l-arabinofuranosidase digestion, 56% of the arabinosyl chains were released. The resistant product (LRGP3-AF) had markedly increased complement fixating activities. The acid hydrolysis product (LRGP3-T) contained (1→3)-linked (17.6%), (1→6)-linked (23.1%), (1→3,6)-linked (30.1%) and terminal (29.2%) galactosyl residues, and its complement fixating activity was lower than that of LRGP3-AF. The side chains (Oligo-S) consisted of arabinose, galactose, and rhamnose in the molar ratios 16.8:1.4:1.0. The complement fixating activity of Oligo-S was weak, but Oligo-S had potent macrophage stimulation activity. Degradation of arabinosyl residues in LRGP3 decreased the macrophage stimulation activity, but the galactan backbone still expressed partial activity. The results demonstrated that the galactan backbone of the polymer might be essential for the expression of complement fixating activity and the arabinosyl side chains could be more responsible for the macrophage activation activity. There may be several structurally different active sites involved in the immunological activity of LRGP3.
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, YangLing 712100, PR China. Electronic address: pengqiang@nwsuaf.edu.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Peng
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, YangLing 712100, PR China.
authors.forename: Hang
authors.initials: H
authors.lastname: Liu
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, YangLing 712100, PR China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Lei
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, YangLing 712100, PR China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Wang
mesh_terms: D005685:Galactans / Q000737:chemistry*; D032305:Lycium / Q000737:chemistry*; D011134:Polysaccharides / Q000032:analysis / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D005685:Galactans; D011134:Polysaccharides; C005653:arabinogalactan
keywords: Arabinogalactan; Lycium ruthenicum; Polysaccharide; Structure activity relationship