Two New Amino-Sugars from an Antigenic Polysaccharide of Pneumococcus

Abstract

THOUGH a large number of antigenic capsular polysaccharides of Pneumococcus are known to contain one or more amino-sugars¹, in only one case, namely, 2-amino-2-deoxy-D-glucose (D-glucosamine) from type XIV polysaccharide², has the amino-sugar been isolated and characterized. Two amino-sugars, designated ‘pneumosamine’ and ‘amino-sugar X’ have been isolated from purified Type V Pneumococcus capsular polysaccharide³, and preliminary investigations, which included analysis of the crystalline N-acetamido alcohol derivatives, indicated that both sugars were 2-amino-2,6-dideoxyhexoses. Kuhn-Roth determinations on ‘N-acetylpneumosaminol’ (1.52 moles CH₃) and on ‘amino-sugar X’ (0.68 mole CH₃) support the postulated 6-deoxyhexosamine structure. The sugars have now been tentatively identified as 2-amino-2,6-dideoxytalose (pneumosamine) and 2-amino-2,6-dideoxy-L-galactose (amino-sugar X). The sugars were isolated from a polysaccharide hydrolysate (hydrolysis conditions: 2 N hydrochloric acid, 24 hr., 100°) by chromatography on ‘Dowex-50’ resin⁴. The acidic effluents were neutralized with ‘Deacidite FF’ (carbonate form), lyophilized and the syrupy residues dried in vacuo over phosphorus pentoxide. Treatment of the ‘pneumosamine’ residue with methanol gave ‘pneumosamine hydrochloride’ melting point 162–3° (from methanol–ether); [α]¹⁸ _D + 6.9° (10 min.), → + 10.4° equil. (cone. 2.3 in water). Found: C, 35.9; H, 7.4 per cent; calc. for C₆H₁₄O₄NCl: C, 36.1; H, 7.1 per cent. ‘Amino-sugar X’ was crystallized from a water–methanol–acetone mixture.