title: Structural characterization of a rhamnogalacturonan I-arabinan-type I arabinogalactan macromolecule from starfruit (Averrhoa carambola L.).
abstract: A structural characterization of polysaccharides obtained from edible tropical fruit named starfruit (Averrhoa carambola L.) was carried out. After fractionation by freeze-thaw and Fehling precipitation, a pectic polysaccharide was obtained. It was composed of rhamnose, arabinose, galactose and uronic acid in the 5.0:72.5:12.1:10.4 molar ratios, respectively. A combination of monosaccharide, GPC, methylation and NMR analysis and enzymatic hydrolysis with endo-β-(1→4)-D-galactanase showed the presence of a rhamnogalacturonan I to which a branched arabinan and a type I arabinogalactan are attached. The arabinan moiety was formed by (1→5)-linked α-L-Araf units in the backbone, branched only at O-3 by (1→2)- and (1→3)-linked α-L-Araf units, while the type I arabinogalactan was formed by (1→4)- and (1→4,6)-linked β-D-Galp units in the backbone with (1→5)-, (1→3,5)- and (1→3)-linked α-L-Araf units as side chains.
authors: Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, CP 19.046, CEP 81.531-980 Curitiba, PR, Brazil.
authors: Carolina Lopes
authors: CL
authors: Leivas
authors: Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, CP 19.046, CEP 81.531-980 Curitiba, PR, Brazil.
authors: Marcello
authors: M
authors: Iacomini
authors: Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, CP 19.046, CEP 81.531-980 Curitiba, PR, Brazil. Electronic address: lucimaramcc@ufpr.br.
authors: Lucimara M C
authors: LM
authors: Cordeiro
mesh_terms: D005685:Galactans / Q000737:chemistry*; D065825:Oxalidaceae / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry*
chemical_list: D005685:Galactans; C042491:rhamnogalacturonan I; D010368:Pectins; C005653:arabinogalactan
keywords: Arabinan; Averrhoa carambola; Starfruit; Type I arabinogalactan; Type I rhamnogalacturonan