- M. Hendrickx (1)
- M.A. Kabel (1)
- A. Loey van (1)
- H.A. Schols (3)
- L. Schoofs (1)
- D.N. Sila (1)
- C. Smout (1)
- R.P. Verhoef (1)
- I. Verlent (1)
- A.G.J. Voragen (2)
CE-MSn of complex pectin-derived oligomers
Coenen, G.J. ; Kabel, M.A. ; Schols, H.A. ; Voragen, A.G.J. - \ 2008
Electrophoresis 29 (2008)10. - ISSN 0173-0835 - p. 2101 - 2111.
anion-exchange chromatography - capillary zone electrophoresis - trap mass-spectrometry - hairy ramified regions - maldi-tof ms - rhamnogalacturonan-i - 8-aminonaphthalene-1,3,6-trisulfonic acid - galacturonic acid - apple pectin - oligosaccharides
As pectin molecules are too large and heterogeneous to analyze as a whole, the polymer is usually degraded to smaller oligomers, which are often analyzed by high-performance anion exchange chromatography (HPAEC). However, the high salt concentration necessary to elute pectin oligomers by HPAEC is incompatible with online mass detection. To overcome such a disadvantage, a CE-IT-MS system was set up to further elucidate the fine structure of charged oligosaccharides. An effective separation of differently substituted galacturonic acid containing oligomers was obtained by low-pH CE-LIF analysis. By adapting the buffer and capillary online MS detection was enabled. Moreover, with MS/MS it was possible to localize sugar residues' substitutions. With this combined CE-MS approach LIF electropherograms of xylogalacturonan and rhamnogalacturonan I digests could be annotated. The method was further exemplified by a complex oligomer mixture of acid hydrolyzed apple pectin, which was separated and characterized by CE-MSn. Oligomers present in low amounts could be localized by their corresponding m/z, as was demonstrated by selected mass range representation.
Identification of the connecting linkage between homo- or xylogalacturonan and rhamnogalacturonan type I
Coenen, G.J. ; Bakx, E.J. ; Verhoef, R.P. ; Schols, H.A. ; Voragen, A.G.J. - \ 2007
Carbohydrate Polymers 70 (2007)2. - ISSN 0144-8617 - p. 224 - 235.
hairy ramified regions - cell-wall polysaccharides - flight mass-spectrometry - pectic polysaccharide - structural features - rhamnose residues - black-currants - cross-linking - apple pectin - side-chain
Pectin is of interest both as cell wall component and as food additive. The precise chemical structure of pectin remains under debate, although the structural elements of pectin are rather well described. In order to get more insight in the inter linkage between the various structural elements, apple pectin modified hairy regions were degraded by controlled acid hydrolysis. From the degradation products oligomeric fragments were selected which could represent interconnection points, and these oligomers were characterized using LC¿MS and NMR approaches. It was shown that the oligomers GalA3Rha1, GalA4Rha2, and GalA5Rha3 consisted out of a homogalacturonan and a rhamnogalacturonan type I segment connected via a GalAp¿-(1 ¿ 2) Rhap linkage. In addition, a GalA6Rha3Xyl1 oligomer was identified, which consisted out of a xylogalacturonan and a rhamnogalacturonan type I segment. These oligomers indicated that in apple pectin both homogalacturonan and xylogalacturonan were covalently linked to rhamnogalacturonan type I. With these new insights, currently used pectin models were refined. Keywords: Homogalacturonan; Xylogalacturonan; Rhamnogalacturonan I; Pectin model; Covalent linkage; Pectin structure
Effect of Temperature and High Pressure on the Activity and Mode of Action of Fungal Pectin Methyl Esterase
Duvetter, T. ; Fraeye, I. ; Sila, D.N. ; Verlent, I. ; Smout, C. ; Clynen, E. ; Schoofs, L. ; Schols, H.A. ; Hendrickx, M. ; Loey, A. van - \ 2006
Biotechnology Progress 22 (2006)5. - ISSN 8756-7938 - p. 1313 - 1320.
aspergillus-niger - apple pectin - pectinmethylesterase - firmness - endopolygalacturonase - methylesterase - infusion - methanol - enzyme - fruits
Pectin was de-esterified with purified recombinant Aspergillus aculeatus pectin methyl esterase (PME) during isothermal-isobaric treatments. By measuring the release of methanol as a function of treatment time, the rate of enzymatic pectin conversion was determined. Elevated temperature and pressure were found to stimulate PME activity. The highest rate of PME-catalyzed pectin de-esterification was obtained when combining pressures in the range 200-300 MPa with temperatures in the range 50-55 C. The mode of pectin de-esterification was investigated by characterizing the pectin reaction products by enzymatic fingerprinting. No significant effect of increasing pressure (300 MPa) and/or temperature (50 C) on the mode of pectin conversion was detected.