PERIODATE-OXIDIZED PHOSPHOMANNAN Y-2448: STRUCTURAL SIGNIFICANCE OF ITS REACTION WITH ALKALI

Abstract

The diesterphosphomannan produced by Hansenula holstii NRRL Y-2448 was shown by periodate-oxidation analysis to have 20% of its D-mannose units linked through carbon-1 only (or carbons-1 and -6), 33% through carbons-1 and -2, and 47% through carbons-1 and -3. Information regarding branching in this macromolecular polysaccharide derivative was not established. The periodate-oxidation product neutralized dilute alkali rapidly at pH 8.5–10.0, with elimination of about 30% of the phosphorus as inorganic orthophosphate. About 80%, inorganic orthophosphate was obtained by longer treatment at pH 10.1–10.5. These observations are shown to support the hypothesis that diesterorthophosphate groups (0.20 mole/mole mannose unit) are held between carbon-6 of units otherwise linked only through carbon-1, and carbon-1 of 60% of the carbon-2-linked units. After periodate oxidation, both phosphoester bonds may undergo β-aldehydo elimination by alkali; the unit having phosphate in hemiacetal linkage and a mannosidic attachment at carbon-2 is presented as the more reactive site. Periodate oxidation also produces sites for β-dealkoxylation by alkali.