title: Tandem mass spectrometric analysis of aspergillus niger pectin methylesterase: mode of action on fully methyl-esterified oligogalacturonates.
abstract: The substrate specificity and the mode of action of Aspergillus niger pectin methylesterase (PME) was determined using both fully methyl-esterified oligogalacturonates with degrees of polymerization (DP) 2-6 and chemically synthesized monomethyl trigalacturonates. The enzymic activity on the different substrates and a preliminary characterization of the reaction products were performed by using high-performance anion-exchange chromatography at neutral pH. Electrospray ionization tandem MS (ESI-MS/MS) was used to localize the methyl esters on the (18)O-labelled reaction products during the course of the enzymic reaction. A. niger PME is able to hydrolyse the methyl esters of fully methyl-esterified oligogalacturonates with DP 2, and preferentially hydrolyses the methyl esters located on the internal galacturonate residues, followed by hydrolysis of the methyl esters towards the reducing end. This PME is unable to hydrolyse the methyl ester of the galacturonate moiety at the non-reducing end.
authors.affiliation: Section Molecular Genetics of Industrial Microorganisms, Wageningen Agricultural University, Dreijenlaan 2, 6703 HA Wageningen, The Netherlands.
authors.forename: H C
authors.initials: HC
authors.lastname: Kester
authors.forename: J A
authors.initials: JA
authors.lastname: Benen
authors.forename: J
authors.initials: J
authors.lastname: Visser
authors.forename: M E
authors.initials: ME
authors.lastname: Warren
authors.forename: R
authors.initials: R
authors.lastname: Orlando
authors.forename: C
authors.initials: C
authors.lastname: Bergmann
authors.forename: D
authors.initials: D
authors.lastname: Magaud
authors.forename: D
authors.initials: D
authors.lastname: Anker
authors.forename: A
authors.initials: A
authors.lastname: Doutheau
mesh_terms: D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology*; D002265:Carboxylic Ester Hydrolases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry; D010368:Pectins / Q000378:metabolism*
chemical_list: D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase