title: Chromatographic fractionation and molecular mass characterization of Cercidium praecox (Brea) gum.
abstract: BACKGROUND
  Brea gum (BG) is an exudate from the Cercidium praecox tree that grows in semi-arid regions of Argentina. Some previous studies on BG have shown physicochemical characteristics and functional features similar to those of gum arabic. However, there is a need to elucidate the molecular structure of BG to understand the functionality. In this sense, BG was fractionated using hydrophobic interaction chromatography and the obtained fractions were analyzed by size exclusion chromatography.
  
  
  RESULTS
  Analysis of the fractions showed that the bulk of the gum (approx. 84% of the polysaccharides) was a polysaccharide of 2.79 × 10(3)  kDa. The second major fraction (approx. 16% of the polysaccharides) was a polysaccharide-protein complex with a molecular mass of 1.92 × 10(5)  kDa. A third fraction consisted of protein species with a wide range of molecular weights. The molecular weight distribution of the protein fraction was analyzed by size exclusion chromatography. Comparison of the elution profiles of the exudates in native and reducing conditions revealed that some of the proteins were forming aggregates through disulfide bridges in native conditions. Further analysis of the protein fraction by SDS-PAGE showed proteins with molecular weight ranging from 6.5 to 66 kDa.
  
  
  CONCLUSIONS
  The findings showed that BG consists of several fractions with heterogeneous chemical composition and polydisperse molecular weight distributions. © 2016 Society of Chemical Industry.
authors.affiliation: Instituto de Tecnología de Alimentos, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Virginia
authors.initials: V
authors.lastname: Castel
authors.affiliation: Department of Food Science and Technology, University of Tennessee, Knoxville, Tennessee, 37996-4539, USA.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Zivanovic
authors.affiliation: Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, 37996-4539, USA.
authors.forename: Juan L
authors.initials: JL
authors.lastname: Jurat-Fuentes
authors.affiliation: Instituto de Tecnología de Alimentos, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Liliana G
authors.initials: LG
authors.lastname: Santiago
authors.affiliation: Instituto de Tecnología de Alimentos, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Amelia C
authors.initials: AC
authors.lastname: Rubiolo
authors.affiliation: Instituto de Tecnología de Alimentos, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Carrara
authors.affiliation: Department of Food Science, Pennsylvania State University, University Park, PA, 16802, USA.
authors.forename: Federico M
authors.initials: FM
authors.lastname: Harte
mesh_terms: D001118:Argentina; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003889:Desert Climate; D004229:Dithiothreitol / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000737:chemistry* / Q000254:growth & development; D005503:Food Additives / Q000032:analysis / Q000737:chemistry; D006170:Gum Arabic / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D053149:Plant Gums / Q000737:chemistry*; D010940:Plant Proteins / Q000032:analysis* / Q000737:chemistry; D011134:Polysaccharides / Q000032:analysis* / Q000737:chemistry; D066329:Protein Aggregates / Q000187:drug effects; D019163:Reducing Agents / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D005503:Food Additives; D010636:Phenols; D010936:Plant Extracts; D053149:Plant Gums; D010940:Plant Proteins; D011134:Polysaccharides; D066329:Protein Aggregates; D019163:Reducing Agents; D013439:Sulfhydryl Reagents; D006170:Gum Arabic; D004229:Dithiothreitol
keywords: Brea gum; Cercidium praecox; molecular mass distribution; plant gum exudate