Cell-wall glucans of Cryptococcus neoformans Cap 67.
Purified cell walls derived from Cryptococcus neofromans Cap 67, an acapsular mutant, consisted of 86% Glc and 7.3% GlcNAc. The integrity of the cell walls was disrupted in three successive extractions with 60% 4-methylmorpholine N-oxide (4-MMNO) at 120 degrees. Four 4-MMNO-soluble D-glucopyranans were isolated. Released within 0.5 h was water-insoluble Gi-1, followed by two water-soluble Gs fractions and water-insoluble Gi-2 over 17.5 h. A 4-MMNO-insoluble residue, containing 27% of GlcNAc, was also isolated. Gi-1 and Gi-2 were isolated as precipitates during dialysis of 4-MMNO extracts and were each reduced with NaBH4 to permit their investigation in alkaline solution. Gs-1 and Gs-2 were separated by ion-exchange chromatography of the water-soluble fractions. The structures of the D-glucopyranans were determined by 13C-n.m.r. spectroscopy and by g.l.c.-mass spectrometry of their per-O-methylated derivatives. Gi-1 was a (1----3)-alpha-D-glucopyranan (97%) with some (1----4)-D-glucosidic linkages (3%) and no chain-branching. Gs-1 and Gs-2 were (1----6)-beta-D-glucopyranans branched at O-3 (10-12%) with beta-D-Glcp-(1----3)-beta-D-Glcp side chains. Gs-2 may have approximately 2% more chain branching than Gs-1. Gi-2 was a D-glucopyranan with 80% of its structure like that of Gi-1, and 20% like that of Gs-1 and -2; the water-insolubility of Gi-2 suggests that these structures were covalently linked. Almost identical D-glucopyranans were obtained from aged cultures that had thickened walls (as observed by electron microscopy).
James
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Department of Chemistry, Georgia State University, Atlanta 30303.
Cherniak
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Jones
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Stortz
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CA
Reiss
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D002473:Cell Wall / Q000032:analysis; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003454:Cryptococcus / Q000032:analysis*; D003455:Cryptococcus neoformans / Q000032:analysis*; D003956:Dialysis; D005612:Freeze Drying; D005936:Glucans / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D015394:Molecular Structure; D009154:Mutation; D010084:Oxidation-Reduction; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification*; D012995:Solubility
D005936:Glucans; D011135:Polysaccharides, Bacterial