Extracellular Galactomannan fromNeurospora crassa

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Abstract
The extracellular galactomannan of Neurospora crassa has been characterized. The purified polysaccharide preparation consisted of more than 98% carbohydrate (d-mannose, 49%; d-galactose, 43%; d-glucose, 8%) and trace amounts of protein (< 1%) and phosphate (< 1%). The native polymer ([α]d, + 28°) was resistant to bacterial exo-α-d-mannanase, while the mannan ([α]d, + 85.9°) after mild acid hydrolysis was partially hydrolyzed by the enzyme. Methylation analysis, Smith degradation, acetolysis, and enzymic and acid hydrolysis indicated that the polysaccharide had a linear α-mannan backbone consisting of α-1,2-tetrasaccharide, α-1,2- and α-1,3-disaccharide units which might be joined by α-1,6-bonds. Galactose residues linked through a β-1,5-bond were located exclusively in the side-chains. The side-chains were attached to the mannan backbone by a 1,2- or 1,6-linkage.