title: Methylesterase behaviour is related to polysaccharide organisation in model systems mimicking cell walls.
abstract: Pectin gels and pectin-cellulose binary gels were used as cell wall-mimicking systems to investigate the diffusion ability of a fungal pectin methylesterase. Increasing content of cellulose in the gel appears to result: (i) in longer demethylated blocks thus favouring AaPME processivity, and (ii) in accelerated enzyme kinetics. To better understand this unexpected behaviour, a method was set up to investigate the gel porosity as a function of the cellulose content by following the passive diffusion of three pullulans having different hydrodynamic volumes. Like the enzyme, the pullulans diffused more efficiently in the gels containing the highest proportions of cellulose. Altogether, these results suggest that the gel settled differently during formation according to the respective proportions of the two polysaccharides. With cellulose present, a fraction of pectin would form close interactions with the microfibrils resulting in a larger volume accessible to diffusing molecules. This volume would be related to the cellulose concentration.
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, La Géraudière, F-44300 Nantes, France. Electronic address: estelle.bonnin@nantes.inra.fr.
authors.forename: Estelle
authors.initials: E
authors.lastname: Bonnin
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, La Géraudière, F-44300 Nantes, France.
authors.forename: Jelena
authors.initials: J
authors.lastname: Mutic
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, La Géraudière, F-44300 Nantes, France.
authors.forename: Jasna
authors.initials: J
authors.lastname: Nikolic
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, La Géraudière, F-44300 Nantes, France.
authors.forename: Sally
authors.initials: S
authors.lastname: Burr
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, La Géraudière, F-44300 Nantes, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Robert
authors.affiliation: INRA, UR1268 Biopolymères Interactions Assemblages, La Géraudière, F-44300 Nantes, France.
authors.forename: Marie-Jeanne
authors.initials: MJ
authors.lastname: Crépeau
mesh_terms: D001230:Aspergillus / Q000201:enzymology; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry*; D004058:Diffusion; D005656:Fungal Proteins / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D008954:Models, Biological; D010368:Pectins / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D005782:Gels; D010368:Pectins; D002482:Cellulose; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase
keywords: Degree of blockiness; Enzymatic demethyl-esterification; Gel porosity; Pectin; Pectin methylesterase; Pectin–cellulose gels