title: A novel alpha-D-galactosynthase from Thermotoga maritima converts beta-D-galactopyranosyl azide to alpha-galacto-oligosaccharides.
abstract: The large-scale production of oligosaccharides is a daunting task, hampering the study of the role of glycans in vivo and the testing of the efficacy of novel glycan-based drugs. Glycosynthases, mutated glycosidases that synthesize oligosaccharides in high yields, are becoming important chemo-enzymatic tools for the production of oligosaccharides. However, while β-glycosynthase can be produced with a rather well-established technology, examples of α-glycosynthases are thus far limited only to enzymes from glycoside hydrolase 29 (GH29), GH31 and GH95 families. α-L-Fucosynthases from GH29 use convenient glycosyl azide derivatives as a strategic alternative to glycosyl fluoride donors. However, the general applicability of this method to other α-glycosynthases is not trivial and remains to be confirmed. Here, β-D-galactopyranosyl azide was converted to α-galacto-oligosaccharides with good yields and high regioselectivity, catalyzed by a novel α-galactosynthase based on the GH36 α-galactosidase from the hyperthermophilic bacterium Thermotoga maritima. These results open a new avenue to the practical synthesis of biologically interesting α-galacto-oligosaccharides and demonstrate more widespread use of β-glycosyl-azide as donors, confirming their utility to expand the repertoire of glycosynthases.
authors.affiliation: Institute of Protein Biochemistry - Consiglio Nazionale delle Ricerche, Via P Castellino 111, 80131 Naples, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Cobucci-Ponzano
authors.forename: Carmela
authors.initials: C
authors.lastname: Zorzetti
authors.forename: Andrea
authors.initials: A
authors.lastname: Strazzulli
authors.forename: Sara
authors.initials: S
authors.lastname: Carillo
authors.forename: Emiliano
authors.initials: E
authors.lastname: Bedini
authors.forename: Maria Michela
authors.initials: MM
authors.lastname: Corsaro
authors.forename: Donald A
authors.initials: DA
authors.lastname: Comfort
authors.forename: Robert M
authors.initials: RM
authors.lastname: Kelly
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Marco
authors.initials: M
authors.lastname: Moracci
mesh_terms: D001224:Aspartic Acid / Q000737:chemistry; D001386:Azides / Q000737:chemistry; D002855:Chromatography, Thin Layer; D004187:Disaccharides / Q000096:biosynthesis; D005690:Galactose / Q000378:metabolism; D005998:Glycine / Q000737:chemistry; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015202:Protein Engineering; D020124:Thermotoga maritima / Q000201:enzymology*; D000519:alpha-Galactosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001386:Azides; D004187:Disaccharides; D050505:Mutant Proteins; D001224:Aspartic Acid; D000519:alpha-Galactosidase; D005998:Glycine; D005690:Galactose