Complexation of vanadium(V) oxyanions with hexopyranose- and mannopyranoseuronic acid-containing polysaccharides: stereochemical considerations.
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.
Departamento de Bioquímica, Universidade Federal dp Paraná, Caixa Postal 19046, 81530-990 Curitiba PR, Brazil.
Cesar A
CA
Tischer
Maria Benigna M
MB
Oliveira
Fany
F
Reicher
Marcello
M
Iacomini
Carmem L O
CL
Petkowicz
Maria Eugênia R
ME
Duarte
Miguel D
MD
Noseda
Philip A J
PA
Gorin
D000838:Anions / Q000737:chemistry; D005690:Galactose / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry; D008358:Mannose / Q000737:chemistry*; D008970:Molecular Weight; D011134:Polysaccharides / Q000138:chemical synthesis / Q000737:chemistry*; D012015:Reference Standards; D013237:Stereoisomerism; D014638:Vanadates / Q000737:chemistry*
D000838:Anions; D006603:Hexuronic Acids; D008351:Mannans; D011134:Polysaccharides; D014638:Vanadates; D008358:Mannose; D005690:Galactose