title: Hydrolysis and speciation of Al bound to pectin and plant cell wall material and its reaction with the dye chrome azurol S.
abstract: Hydrolysis of aluminum (Al) in solution increases at pH >or= 4 and with an Al concentration. Pectin, an important anionic polysaccharide of plant cell walls, adsorbs Al, but this phenomenon is poorly understood. This study showed that Al(3+) hydrolysis results in binding of Al to pectin in excess of the stoichiometric equivalent, leading to oversaturation of the pectin with Al. However, the degree of pectin methyl-esterification did not affect the extent of Al hydrolysis. Binding of Al to purified cell wall material also resulted in Al hydrolysis in a pH- and soluble Al concentration-dependent manner, but the source of cell wall material had no effect at fixed pH. Staining of Al-treated pectin and cell wall material from wheat ( Triticum aestivum L.) and sunflower ( Helianthus annuus L.) with the Al-specific dye, chrome azurol S (CAS), resulted in the formation of a purple color, with the intensity related to the extent of Al hydrolysis.
authors.affiliation: School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland, Australia. b.wehr@uq.edu.au
authors.forename: J Bernhard
authors.initials: JB
authors.lastname: Wehr
authors.forename: F P C
authors.initials: FP
authors.lastname: Blamey
authors.forename: J V
authors.initials: JV
authors.lastname: Hanna
authors.forename: P M
authors.initials: PM
authors.lastname: Kopittke
authors.forename: G L
authors.initials: GL
authors.lastname: Kerven
authors.forename: N W
authors.initials: NW
authors.lastname: Menzies
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D002473:Cell Wall / Q000737:chemistry*; D006368:Helianthus / Q000737:chemistry*; D006868:Hydrolysis; D062385:Hydroxybenzoates / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry*; D014908:Triticum / Q000737:chemistry*
chemical_list: D062385:Hydroxybenzoates; C015076:chrome azurol S; D010368:Pectins; D000535:Aluminum