title: Chemoenzymatic syntheses of linear and branched hemithiomaltodextrins as potential inhibitors for starch-debranching enzymes.
abstract: Oligosaccharides embodying the S-maltosyl-6-thiomaltosyl structure have been readily synthesised by using convergent chemoenzymatic approaches. The key steps for the preparation of these molecules involved: 1) transglycosylation reactions of maltosyl fluorides onto suitable acceptors catalysed by the bacterial transglycosylase, cyclodextrin glycosyltransferase (CGTase), and 2) the SN2-type displacement of a 6-halide from acetylated acceptors by activated 1-thioglycoses. The target molecules, which were obtained in good overall yields, proved to be useful for investigating substrate binding in the active sites of several enzymes that act upon the alpha-1,6-linkage of pullulan and/or amylopectin. The compounds exhibit Ki values in the 2.5-1350 microM range with the different enzymes, and the highest affinity found by using these molecules was seen for the pullulanase from Bacillus acidopullulyticus. Both barley-malt limit dextrinase and pullulanase type II from Thermococcus hydrothermalis only recognised the longest linear thiooligosaccharide, while a branched heptasaccharide was the strongest inhibitor of pullulanase from Klebsiella planticola.
authors.affiliation: Centre de Recherches sur les Macromolécules Végétales (CERMAV-CNRS), Université Joseph Fourier B.P. 53, 38041 Grenoble, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Greffe
authors.forename: Morten T
authors.initials: MT
authors.lastname: Jensen
authors.forename: Florent
authors.initials: F
authors.lastname: Chang-Pi-Hin
authors.forename: Sandra
authors.initials: S
authors.lastname: Fruchard
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Donohue
authors.forename: Birte
authors.initials: B
authors.lastname: Svensson
authors.forename: Hugues
authors.initials: H
authors.lastname: Driguez
mesh_terms: D000107:Acetylation; D001407:Bacillus / Q000201:enzymology; D001665:Binding Sites; D001667:Binding, Competitive; D002240:Carbohydrate Sequence; D003912:Dextrins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors*; D006031:Glycosylation; D006868:Hydrolysis; D007700:Kinetics; D007709:Klebsiella / Q000201:enzymology; D008320:Maltose / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D013213:Starch / Q000378:metabolism*; D019712:Thermococcus / Q000201:enzymology
chemical_list: D003912:Dextrins; D004791:Enzyme Inhibitors; D009844:Oligosaccharides; D008320:Maltose; D013213:Starch; D006026:Glycoside Hydrolases