title: Beta-D-galactopyranosyl azide: its one-step quantitative synthesis using E461G-beta-galactosidase (Escherichia coli) and a demonstration of its potential as a reagent for molecular biology.
abstract: A simple one-step synthesis of beta-D-galactopyranosyl azide from o-nitrophenyl-beta-D-galactopyranoside and azide catalyzed by E461G-beta-galactosidase is described. The synthesis is quantitative in the presence of excess azide and only the beta anomer is produced. The product was purified (71% yield) from the other reaction components by extraction with ethyl acetate, silica gel chromatography, and crystallization. The purity was verified by GLC, TLC, and NMR. Thus, E461G-beta-galactosidase is able to specifically and quantitatively form beta-D-galactopyranosyl-azide. The purified beta-D-galactopyranosyl azide inhibited the growth of Escherichia coli that express beta-galactosidase but not of E. coli that do not. Growth is stopped because beta-galactosidase catalyzes the hydrolysis of the beta-galactopyranosyl-azide, and the azide that is produced inhibits cell growth. This selective inhibition of growth has potential application in molecular biology screening.
authors.affiliation: Division of Biochemistry, Faculty of Science, University of Calgary, Calgary, Alberta, Canada T2N 1 N4.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Rob
authors.forename: Reuben E
authors.initials: RE
authors.lastname: Huber
mesh_terms: D001386:Azides / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D005690:Galactose / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D012680:Sensitivity and Specificity; D013045:Species Specificity; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000737:chemistry*
chemical_list: D001386:Azides; D011994:Recombinant Proteins; C477368:galactopyranosyl azide; D001616:beta-Galactosidase; D005690:Galactose