Cell walls of Coccidioides immitis: neutral sugars of aqueous alkaline extract polymers

The neutral sugar components of hydrolysates of the alkali-soluble and -insoluble fractions of an acid-extracted Coccidioides immitis mycelial cell wall preparation were examined by gas-liquid chromatography. The alkali-soluble fraction was separated into a neutral water-soluble (46% carbohydrate) and a neutral water-insoluble fraction (6% carbohydrate). Glucose was the major neutral sugar constituent of all fractions. Mannose appeared to be a second major component of the alkali-soluble, water-soluble fraction. 3-O-methylmannose was absent. Small amounts of other sugars, including galactose and pentoses, were tentatively identified. Borohydride reduction before alkaline extraction resulted in retention of almost half of the glucose and variable amounts of other components in the alkaline residue, indicating that solubilization of cell wall polymers by alkaline extraction results in significant degradation of the native cell wall polymers.