title: Starch- and glycogen-debranching and branching enzymes: prediction of structural features of the catalytic (beta/alpha)8-barrel domain and evolutionary relationship to other amylolytic enzymes.
abstract: Sequence alignment and structure prediction are used to locate catalytic alpha-amylase-type (beta/alpha)8-barrel domains and the positions of their beta-strands and alpha-helices in isoamylase, pullulanase, neopullulanase, alpha-amylase-pullulanase, dextran glucosidase, branching enzyme, and glycogen branching enzymes--all enzymes involved in hydrolysis or synthesis of alpha-1,6-glucosidic linkages in starch and related polysaccharides. This has allowed identification of the transferase active site of the glycogen debranching enzyme and the locations of beta-->alpha loops making up the active sites of all enzymes studied. Activity and specificity of the enzymes are discussed in terms of conserved amino acid residues and loop variations. An evolutionary distance tree of 47 amylolytic and related enzymes is built on 37 residues representing the four best conserved beta-strands of the barrel. It exhibits clusters of enzymes close in specificity, with the branching and glycogen debranching enzymes being the most distantly related.
authors.affiliation: Department of Chemistry, Carlsberg Laboratory, Copenhagen Valby, Denmark.
authors.forename: H M
authors.initials: HM
authors.lastname: Jespersen
authors.forename: E A
authors.initials: EA
authors.lastname: MacGregor
authors.forename: B
authors.initials: B
authors.lastname: Henrissat
authors.forename: M R
authors.initials: MR
authors.lastname: Sierks
authors.forename: B
authors.initials: B
authors.lastname: Svensson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D005075:Biological Evolution; D002240:Carbohydrate Sequence; D017124:Conserved Sequence; D006004:Glycogen Debranching Enzyme System / Q000737:chemistry* / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006004:Glycogen Debranching Enzyme System; D006026:Glycoside Hydrolases; D000516:alpha-Amylases