Binding studies on internal immunodeterminants: synthesis of β-(1 → 6)-linked oligosaccharide methyl glycosides having one to four internal d-galactopyranosyl residues flanked by gentiobiose residues
摘要:
The oligosaccharide glycosides beta-D-Glc p-(1 --> 6)-beta-D-Glc p-(1 --> 6)-[beta-D-Gal p-(1 --> 6)]n-beta-D-Glc p-(1 --> 6)-beta-D-Glc p-1 --> OMe (n = 1-4) were prepared by a convergent block synthesis. Haloacetyl, tert-butyldiphenylsilyl, and dimethylthexylsilyl groups were used as temporary protective groups for the preparation of the intermediate glycosyl donors and acceptors. The deoxygenated trisaccharide glyco-sides beta-D-Glc p-(1 --> 6)-beta-D-Gal p-(1 --> 6)-4-deoxy-beta-D-xylo-Hex p-1 --> OMe and beta-D-Glc p-(1 --> 6)-4-deoxy-beta-D-xylo-Hex p-(1 --> 6)-beta-D-Gal p-1 --> OMe were also synthesized. The binding of each glycoside to the monoclonal antigalactan antibody IgA 1539 was studied and the results support the previous finding that J539 can bind to internal antigenic epitopes. The data are consistent with the interpretation that subsite C of that antibody binds glucose with a K(a) of approximately 6 (cf. 10.9 for galactose).