Chromatographic fractionation and molecular mass characterization of Cercidium praecox (Brea) gum

VIRGINIA CASTEL; SVETLANA ZIVANOVIC; JUAN LUIS JURAT-FUENTES; LILIANA GABRIELA SANTIAGO; AMELIA CATALINA RUBIOLO; CARLOS ROBERTO CARRARA; FEDERICO M. HARTE

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2016 vol. 9 p. 4345 - 4350

0022-5142

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 gumarabic. However, there is a need to elucidate the molecular structure of BG to understand the functionality. In this sense, BGwas fractionated using hydrophobic interaction chromatography and the obtained fractions were analyzed by size exclusionchromatography.RESULTS: Analysis of the fractions showed that the bulk of the gum (approx. 84% of the polysaccharides) was a polysaccharideof 2.79 × 10 3 kDa. The second major fraction (approx. 16% of the polysaccharides) was a polysaccharide?protein complex witha molecular mass of 1.92 × 10 5 kDa. A third fraction consisted of protein species with a wide range of molecular weights. Themolecular weight distribution of the protein fraction was analyzed by size exclusion chromatography. Comparison of the elutionprofiles of the exudates in native and reducing conditions revealed that some of the proteins were forming aggregates throughdisulfide bridges in native conditions. Further analysis of the protein fraction by SDS-PAGE showed proteins with molecularweight ranging from 6.5 to 66 kDa.CONCLUSIONS: The findings showed that BG consists of several fractions with heterogeneous chemical composition andpolydisperse molecular weight distributions.