PubMed:3072079 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PubMed/sourceid/3072079","sourcedb":"PubMed","sourceid":"3072079","source_url":"http://www.ncbi.nlm.nih.gov/pubmed/3072079","text":"Type-specific polysaccharides of Cryptococcus neoformans. n.m.r.-spectral study of a glucuronomannan chemically derived from a Tremella mesenterica exopolysaccharide.\nA glucuronomannan (GM) was derived by removal, through Smith degradation, of xylose from the native (3-O-acetylglucurono)xylomannan exopolysaccharide isolated from Tremella mesenterica. 13C-N.m.r. chemical shifts measured at various pD values were compared for p-nitrophenyl beta-D-glucopyranosiduronic acid (1) and two GMs (2 and 3) differing in GlcA content (Man:GlcA; 2, 10:1; and 3, 5:1). Also measured and compared were pKa values for 1 and 2. One-dimensional and two-dimensional (COSY and HETCOR) n.m.r. data allowed unambiguous assignments of pD-sensitive chemical shifts due to 2-O-beta-D-GlcpA substituents attached to a (1----3)-linked alpha-D-Manp backbone. The pKa and n.m.r. data indicated that the CO2H groups in either GM are independent of each other, and are similar in behavior to those of p-nitrophenyl beta-D-glucopyranosiduronic acid molecules. The n.m.r. data confirmed the previous, chemically deduced, structural role of GlcpA in the native polysaccharide from T. mesenterica, and indicated that significant pD-induced changes occur in the stabilities of the glycosidic orientations in the GM. Previous 13C-n.m.r. assignments for 2-O-beta-D-GlcpA in polysaccharides derived from Cryptococcus neoformans serotype A-variant were confirmed, except for the signal due to the anomeric carbon atom. This signal is now known to be pD-sensitive. In acidic solutions, it is coincident with the signal (104.5 p.p.m.) due to the anomeric carbon atoms of the unsubstituted alpha-D-Manp backbone residues. In basic solutions, the 2-O-beta-D-GlcpA anomeric carbon resonance is shifted upfield by approximately 0.2 p.p.m., and is observed as a separate signal.","tracks":[{"project":"sentences","denotations":[{"id":"TextSentencer_T1","span":{"begin":0,"end":166},"obj":"Sentence"},{"id":"TextSentencer_T2","span":{"begin":167,"end":352},"obj":"Sentence"},{"id":"TextSentencer_T3","span":{"begin":353,"end":559},"obj":"Sentence"},{"id":"TextSentencer_T4","span":{"begin":560,"end":615},"obj":"Sentence"},{"id":"TextSentencer_T5","span":{"begin":616,"end":835},"obj":"Sentence"},{"id":"TextSentencer_T6","span":{"begin":836,"end":1032},"obj":"Sentence"},{"id":"TextSentencer_T7","span":{"begin":1033,"end":1284},"obj":"Sentence"},{"id":"TextSentencer_T8","span":{"begin":1285,"end":1483},"obj":"Sentence"},{"id":"TextSentencer_T9","span":{"begin":1484,"end":1528},"obj":"Sentence"},{"id":"TextSentencer_T10","span":{"begin":1529,"end":1683},"obj":"Sentence"},{"id":"TextSentencer_T11","span":{"begin":1684,"end":1836},"obj":"Sentence"},{"id":"T1","span":{"begin":0,"end":166},"obj":"Sentence"},{"id":"T2","span":{"begin":167,"end":352},"obj":"Sentence"},{"id":"T3","span":{"begin":353,"end":559},"obj":"Sentence"},{"id":"T4","span":{"begin":560,"end":615},"obj":"Sentence"},{"id":"T5","span":{"begin":616,"end":835},"obj":"Sentence"},{"id":"T6","span":{"begin":836,"end":1032},"obj":"Sentence"},{"id":"T7","span":{"begin":1033,"end":1284},"obj":"Sentence"},{"id":"T8","span":{"begin":1285,"end":1483},"obj":"Sentence"},{"id":"T9","span":{"begin":1484,"end":1528},"obj":"Sentence"},{"id":"T10","span":{"begin":1529,"end":1683},"obj":"Sentence"},{"id":"T11","span":{"begin":1684,"end":1836},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"attributes":[{"subj":"TextSentencer_T1","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T2","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T3","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T4","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T5","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T6","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T7","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T8","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T9","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T10","pred":"source","obj":"sentences"},{"subj":"TextSentencer_T11","pred":"source","obj":"sentences"},{"subj":"T1","pred":"source","obj":"sentences"},{"subj":"T2","pred":"source","obj":"sentences"},{"subj":"T3","pred":"source","obj":"sentences"},{"subj":"T4","pred":"source","obj":"sentences"},{"subj":"T5","pred":"source","obj":"sentences"},{"subj":"T6","pred":"source","obj":"sentences"},{"subj":"T7","pred":"source","obj":"sentences"},{"subj":"T8","pred":"source","obj":"sentences"},{"subj":"T9","pred":"source","obj":"sentences"},{"subj":"T10","pred":"source","obj":"sentences"},{"subj":"T11","pred":"source","obj":"sentences"}]},{"project":"NCBITAXON","denotations":[{"id":"T1","span":{"begin":33,"end":56},"obj":"OrganismTaxon"},{"id":"T2","span":{"begin":127,"end":147},"obj":"OrganismTaxon"},{"id":"T3","span":{"begin":331,"end":351},"obj":"OrganismTaxon"},{"id":"T4","span":{"begin":1370,"end":1404},"obj":"OrganismTaxon"}],"attributes":[{"id":"A1","pred":"db_id","subj":"T1","obj":"5207"},{"id":"A2","pred":"db_id","subj":"T2","obj":"5217"},{"id":"A3","pred":"db_id","subj":"T3","obj":"5217"},{"id":"A4","pred":"db_id","subj":"T4","obj":"178876"},{"subj":"T1","pred":"source","obj":"NCBITAXON"},{"subj":"T2","pred":"source","obj":"NCBITAXON"},{"subj":"T3","pred":"source","obj":"NCBITAXON"},{"subj":"T4","pred":"source","obj":"NCBITAXON"}]},{"project":"Anatomy-UBERON","denotations":[{"id":"T1","span":{"begin":826,"end":834},"obj":"Body_part"},{"id":"T2","span":{"begin":1665,"end":1673},"obj":"Body_part"}],"attributes":[{"id":"A1","pred":"uberon_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/UBERON_0001130"},{"id":"A2","pred":"uberon_id","subj":"T2","obj":"http://purl.obolibrary.org/obo/UBERON_0001130"},{"subj":"T1","pred":"source","obj":"Anatomy-UBERON"},{"subj":"T2","pred":"source","obj":"Anatomy-UBERON"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"sentences","color":"#ec93e3","default":true},{"id":"NCBITAXON","color":"#93ecdb"},{"id":"Anatomy-UBERON","color":"#ecc193"}]}]}}