title: New methods for chemo-enzymatic galactosidation of 2S rapeseed protein.
abstract: Two chemo-enzymatic methodologies to synthesize neoglycoproteins from rapeseed 2S protein (napin) were developed. In the first approach, glycosidases were used to catalyse 1-O-glycosylation of serine residues, whereas in the second one, 6-N-galactosylation was examined using an amino-reduction reaction between the epsilon-NH2 of lysine residues and 6-oxogalactosides (readily available by means of the oxidation reaction of the corresponding galactosides mediated by galactose oxidase). Our results indicated that glycosidases were unable to glycosylate native proteins. Conversely, this reaction was possible, although in low yields (10%), after the introduction of a hydroxyethylene spacer. The latter modified proteins were obtained via the condensation of epsilon-NH2 of lysines with ethylene carbonate in basic medium (40% yield). The second approach was much more efficient, as 61% of the lysine residues were shown to be 6-N-galactosylated using sodium cyanoborohydride as a reduction reagent.
authors.affiliation: Unité de Recherches en Biocatalyse (FRE-CNRS 2230), Faculté des Sciences et des Techniques, BP 92208, F-44322-Nantes, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: André
authors.forename: Sébastien
authors.initials: S
authors.lastname: Niamke
authors.forename: Alice
authors.initials: A
authors.lastname: Faure
authors.forename: Bernard
authors.initials: B
authors.lastname: Colas
authors.forename: Serge
authors.initials: S
authors.lastname: Bérot
authors.forename: Colette
authors.initials: C
authors.lastname: Larré
authors.forename: Jacques
authors.initials: J
authors.lastname: Guéguen
authors.forename: Claude
authors.initials: C
authors.lastname: Rabiller
mesh_terms: D055516:2S Albumins, Plant; D001671:Biochemistry / Q000379:methods; D029741:Brassica rapa / Q000737:chemistry*; D005696:Galactosidases / Q000737:chemistry / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis* / Q000737:chemistry*; D006031:Glycosylation; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D015394:Molecular Structure; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D055516:2S Albumins, Plant; D006023:Glycoproteins; D010940:Plant Proteins; C050363:napin protein, Brassica napus; D005696:Galactosidases; D008239:Lysine