Two distinct classes of polyuronide from the cell walls of a dimorphic fungus, Mucor rouxii.

Polyuronides were extracted from purified yeast and mycelial walls of Mucor rouxii by sequential treatments with lithium chloride and potassium hydroxide and were fractionated by ion-exchange chromatography on DEAE-Sephadex. Two polymers (I and II) of different acidity were found in both wall types. Polymer I contained D-glucuronic acid, L-fucose, D-mannose, and much smaller amounts of D-galactose. Yeast and mycelial polymer I had similar uronic acid contents but differed in their neutral sugar compositions and molecular weights. Polymer II from both cell types contained largely D-glucuronic acid and had similar molecular weights. On partial acid hydrolysis, both polymers I and II gave rise to insoluble glucuronans which appeared to be homopolymeric. One-third of the total uronosyl residues of polymer I, and almost all of the uronosyl residues of polymer II, were present in homopolymeric segments. However, homopolymers derived from polymers I and II may not be identical.