A cell wall proteo-heteroglycan from Piricularia oryzae: further studies of the structure

The carbohydrate part of a proteo-heteroglycan from Piricularia oryzae was further studied by chemical and immunological methods. Acetolysis studies of the proteo-heteroglycan and exo-alpha-D-mannanase resistant core showed a (1 leads to 6) mannan back-bone structure with side chains composed of one to four mannose units, and some of which are terminated by D-glucose or D-galactofuranose. The mode of attachment of the terminal glucose was characterized to be alphaGlc(1 leads to 6)Man by inhibition reaction with oligosaccharides. Rabbit anti-serum formed against P. oryzae cells had three specificities, the first one for alphaGlc(1 leads to 6)alphamannosyl, the second one for alphaMan(1 leads to 3)alphamannosyl, and the last one for alphaGal-f(1 leads to 2)alphamannosyl residues. The most immunodominant side chain structure of the P. oryzae heteroglycan was shown to be alphaGlc(1 leads to 6)alphaMan(1 leads to 2)alphaMan(1 leads to 2)Man.