| This dissertation describes studies on oligosaccharide phytoalexin elicitors from fungal and plant cell walls. The fungal elicitors are highly flexible oligoglucosides (DP 6-7). To determine the bioactive conformation of these oligoglucosides, we pursued two complementary strategies. (1) To identify the bioactive conformation of an elicitor-active hexaglucoside, we explored a five-step molecular modeling protocol involving GEGOP energy minimization, Metropolis Monte Carlo simulations and cluster analysis. We found a particular cluster of backbone conformers of the hexaglucoside that accounts for ;The availability of selectively deuterated hexaglucosides and of a number of structurally related oligosaccharides (from Professor T. Ogawa) made the complete assignment of the ;We also investigated the disaccharide substructure of the hexaglucoside gentiobiose, Glc;Plant (endogenous) elicitors are oligogalacturonides (DP 10-14). Plant cell wall oligogalacturonides with degree of polymerization between 6 and 16 were isolated from a partial hydrolysate of pectin. The oligosaccharides were purified (... |
