title: Characterisation of branched gluco-oligosaccharides to study the mode-of-action of a glucoamylase from Hypocrea jecorina.
abstract: In the conversion of starch to fermentable glucose for bioethanol production, hydrolysis of amylopectin by α-amylases and glucoamylases is the slowest step. In this process, α-1,6-branched gluco-oligosaccharides accumulate and are slowly degraded. Glucoamylases that are able to degrade such branched oligosaccharides faster are economically beneficial. This research aimed at the isolation and characterisation of branched gluco-oligosaccharides produced from amylopectin digestion by α-amylase, to be used as substrates for comparing their degradation by glucoamylases. Branched gluco-oligosaccharides with a DP between five and twelve were purified using size exclusion chromatography. These structures were characterised after labelling with 2-aminobenzamide using UHPLC-MS(n) analysis. Further, the purified oligosaccharides were used to evaluate the mode-of-action of a glucoamylase from Hypocrea jecorina. The enzyme cleaves the α-1,4-linkage adjacent to the α-1,6-linkage at a lower rate than that of α-1,4-linkages in linear oligosaccharides. Hence, the branched gluco-oligosaccharides are a suitable substrate to evaluate glucoamylase activity on branched structures.
authors.affiliation: Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands. Electronic address: melliana.jonathan@wur.nl.
authors.forename: M C
authors.initials: MC
authors.lastname: Jonathan
authors.affiliation: DuPont Industrial Biosciences (Genencor International B.V.), Archimedesweg 30, 2333 CN Leiden, The Netherlands. Electronic address: marco.van.brussel@dupont.com.
authors.forename: M
authors.initials: M
authors.lastname: van Brussel
authors.affiliation: DuPont Industrial Biosciences (Genencor International B.V.), Archimedesweg 30, 2333 CN Leiden, The Netherlands. Electronic address: martijn.scheffers@dupont.com.
authors.forename: M S
authors.initials: MS
authors.lastname: Scheffers
authors.affiliation: Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands. Electronic address: mirjam.kabel@wur.nl.
authors.forename: M A
authors.initials: MA
authors.lastname: Kabel
mesh_terms: D000687:Amylopectin / Q000737:chemistry / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism*; D035901:Hypocrea / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D013058:Mass Spectrometry; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D009844:Oligosaccharides; D011134:Polysaccharides; C008315:maltodextrin; D000687:Amylopectin; D000516:alpha-Amylases; C501919:alpha-amylase, Bacillus licheniformis; D005087:Glucan 1,4-alpha-Glucosidase
keywords: Amylopectin; Gluco-oligosaccharide; Glucoamylase; Maltodextrins