Complexation of vanadium(V) oxyanions with hexopyranose- and mannopyranoseuronic acid-containing polysaccharides: stereochemical considerations
| Autor: | Cesar A. Tischer, Carmem L.O. Petkowicz, Marcello Iacomini, Philip A.J. Gorin, Maria Eugênia R. Duarte, Miguel D. Noseda, Fany Reicher, Maria Benigna M. Oliveira |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Anions
Steric effects Anomer Stereochemistry Diol Vanadium chemistry.chemical_element Polysaccharide Biochemistry Analytical Chemistry Mannans chemistry.chemical_compound Polysaccharides Side chain Vanadate chemistry.chemical_classification Hexuronic Acids Organic Chemistry Galactose Stereoisomerism General Medicine Nuclear magnetic resonance spectroscopy Reference Standards Molecular Weight chemistry Vanadates Mannose |
| Zdroj: | Carbohydrate Research. 339:771-775 |
| ISSN: | 0008-6215 |
| DOI: | 10.1016/j.carres.2003.12.025 |
| Popis: | Carbohydrates containing galactopyranosyl and mannopyranosyl units with vicinal cis-diols were treated with NaVO(3) in D(2)O, and complexation was determined by (51)V NMR spectroscopy. Me alpha-Galp, Me beta-Galp (3,4-cis-diols), and Me alpha-Manp (2,3-cis-diol) complexed, but Me beta-Manp barely did so. This low degree of complexation also occurred with a beta-mannan containing alternate (1--3)- and (1--4)-linkages and an alginate having beta-ManpA blocks. In contrast, branched alpha-mannans complexed readily, although the (51)V resonances for one with side chains terminated with alpha-Manp-(1--3)-alpha-Manp-(1--differed from another with only alpha-Manp-(1--2)-alpha-Manp-(1--groups. The anomeric configuration of Me alpha-Galp and Me beta-Galp, each with 3,4-cis-diols remote from C-1, gave rise to three (51)V signals of complexes with similar shifts and proportions. The shifts of a galactomannan with terminal alpha-Galp-(1--2)-alpha-Manp- were the same as those with alpha-Galp-(1--6)-beta-Manp- groups, but fewer complexes were formed with the former structure, probably due to greater steric crowding of the vanadate esters. Most of the complexes gave rise to a signal in the delta515 region, consistent with the dimeric trigonal-bipyramidal structure. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect