The Nephritogenic Glycopeptide from Rat Glomerular Basement Membrane. X. Synthesis of an N-Triglycosyl Dipeptide and Characteristics of Its cis-trans Isomers.
Isomers of O-alpha-D-glucopyranosyl-(1----6)-O-beta-D-glucopyranosyl- (1----6)-N-[L-aspart-1-oyl-(L-proline)-4-oyl]-alpha-D-glucopyranos ylamine have been prepared, as models for a derivative possibly present in the glomerular basement membrane of rats, by condensation of the corresponding dipeptide derivative (5) with triglycosylamine (4) in the presence of O,O-diethylcyanophosphonate, followed by deprotection of the trisaccharide-dipeptide derivative. During the deprotection process, cis- and trans-isomers containing proline were separated by silica gel column chromatography and also reversed-phase high performance liquid chromatography.