title: New structural features of Acacia tortuosa gum exudate.
abstract: Acacia tortuosa produces a clear gum, very soluble in water. Previous reports showed that it was constituted by four fractions, one of them an arabinogalactan-protein complex. The elucidation of the A. tortuosa gum structure by the combination of classical chemical methods, size exclusion chromatography and NMR spectroscopy, was the objective of this investigation. The data obtained show that the heteropolysaccharide is an arabinogalactan type II, highly ramified, with lateral chains at C-2 as well as at C-6 of the galactose 3-O residues; mono-O-substituted galactoses were not detected. There are residues of mannose, the arabinose, pyranose predominantly, is terminal and 2-O-linked. The abundance of the 4-O-methyl-α-d-glucuronic acid was not previously reported. The proteic fraction is probably represented by an arabinogalactan-protein complex that binds poorly with β-glucosyl Yariv reagent, and two glycoproteins. The NMR spectra suggest that the carbohydrate links to hydroxyproline through the galactose (galactosylation).
authors.affiliation: Centro de Investigaciones en Química de los Productos Naturales, Facultad de Humanidades y Educación, Universidad del Zulia, P.O. BOX 526, Maracaibo, Venezuela. Electronic address: mmartinez.luz@gmail.com.
authors.forename: Maritza
authors.initials: M
authors.lastname: Martínez
authors.affiliation: Centro de Investigaciones en Química de los Productos Naturales, Facultad de Humanidades y Educación, Universidad del Zulia, P.O. BOX 526, Maracaibo, Venezuela. Electronic address: olga.beltran@hdes.luz.edu.ve.
authors.forename: Olga
authors.initials: O
authors.lastname: Beltrán
authors.affiliation: Centro de Investigaciones en Química de los Productos Naturales, Facultad de Humanidades y Educación, Universidad del Zulia, P.O. BOX 526, Maracaibo, Venezuela. Electronic address: frinconciqpn@gmail.com.
authors.forename: Fernando
authors.initials: F
authors.lastname: Rincón
authors.affiliation: Centro de Investigaciones en Química de los Productos Naturales, Facultad de Humanidades y Educación, Universidad del Zulia, P.O. BOX 526, Maracaibo, Venezuela. Electronic address: gladysleondepinto@yahoo.es.
authors.forename: Gladys
authors.initials: G
authors.lastname: León de Pinto
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Cádiz, Puerto Real, Cádiz, Spain. Electronic address: josemanuel.igartuburu@uca.es.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Igartuburu
mesh_terms: D000045:Acacia / Q000737:chemistry*; D005685:Galactans / Q000737:chemistry*; D020723:Glucuronic Acid; D006023:Glycoproteins / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D005685:Galactans; D006023:Glycoproteins; D020723:Glucuronic Acid; C005653:arabinogalactan
keywords: Acacia tortuosa; Galactosylation; Gum exudate; NMR spectroscopy; Proteic fraction