Structural characterisation of hemicellulosic polysaccharides from Benincasa hispida using specific enzyme hydrolysis, ion exchange chromatography and MALDI-TOF mass spectroscopy

摘要: Abstract Benincasa hispida fruit is an important source of water-soluble polysaccharides. Hemicellulosic polysaccharides extracted with 1- and 4-M KOH represented 120 mg/g alcohol insoluble residues. The intrinsic viscosity the polymers (named B1OH B4OH fractions) was 284 262 ml/g, respectively. polymers, which were further characterised by size exclusion chromatography, give one broad peak. apparent molecular weight isolated polysaccharide estimated to be around 130±40 kDa. Sugar composition analysis both fractions demonstrates presence xyloglucan (XG) xylan. Structural characterisation hemicellulosic using specific enzyme hydrolysis, ion exchange chromatography (HPAEC) Matrix Assisted Laser Desorption Ionisation-Time Flight (MALDI-TOF) mass spectroscopy showed that B. XG XXXG type contained XXXG, XXLG, XXFG XLFG according Fry et al. 1993 ) in ratio 31:28:41 as major oligomeric subunits. This fucogalactoxyloglucan carries O -acetyl substituents exclusively on galactose-containing oligosaccharides Finally, hydrolysis together HPAEC MALDI-TOF-mass spectrometric generated fragments shows xylans, also present fractions, exhibit a classical structure backbone β-(1→4)-linked xylopyranosyl residues substituted three 4- -methyl glucuronic acid per 97 unit.