Structural analysis of (methyl-esterified) oligogalacturonides using post-source decay matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The use of post-source decay matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the structural analysis of ((partly) methyl-esterified) oligogalacturonides (oligoGalA) is described. The fragmentation behavior of purified (un)saturated oligoGalA (degree of polymerization 3-6), methyl-esterified and methyl-glycosydated oligoGalA was studied. General fragmentation patterns are described and used for the elucidation of the positions of methyl esters on partly methyl-esterified oligoGalA. This technique now permits the determination of the position of methyl esters or other substituents on pectic fragments, helping in understanding the mode of action of pectinolytic enzymes. Copyright 2000 John Wiley & Sons, Ltd.