title: Enzymatic synthesis of aliphatic beta-lactosides as mimic units of glycosphingolipids by use of Trichoderma reesei cellulase.
abstract: Aliphatic beta-lactosides were directly synthesized by beta-lactosyl transfer reaction from p-nitrophenyl beta-lactoside (Lac beta-pNP) to various 1-alkanols (n = 2-12), utilizing commercially available cellulase preparation of Trichoderma reesei C1. With ethanol acceptor, the enzyme induced ethyl beta-lactoside (1) in 18% yield based on the donor added in aqueous buffer system. When 1-octanol and dodecanol were acceptors, octyl beta-lactoside (2) and dodecyl beta-lactoside (3) were also obtained as transfer products, respectively. In both cases, the addition of sodium cholate as detergent to the reaction system ensured a sufficient solubility of these acceptors and resulted in a remarkable increase of the desired compounds (5-13% yields based on the donor added). Furthermore, the enzyme catalyzed the N-acetyllactosaminyl transfer reaction from p-nitrophenyl beta-N-acetyllactosaminide (LacNAc beta-pNP) not only to 1-alkanol, but also to the OH-4 position of Man and Glc to produce the trisaccharides, Gal beta1-4GlcNAc beta1-4Man (4) and Gal beta1-4GlcNAc beta1-4Glc (5), respectively. The enzyme activities transferring lactosyl and N-acetyllactosaminyl groups were not separated by chromatographies using DEAE-Sepharose Fast Flow and Sephadex 75 pg columns, indicating that the two reactions were catalyzed by a single enzyme. It was specified that a single enzyme works both transglycosylations, based on the substrate competition assay on hydrolysis.
authors.affiliation: Science of Biological Resource, The United Graduate School of Agricultural Science, Gifu University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Totani
authors.forename: N
authors.initials: N
authors.lastname: Yasutake
authors.forename: H
authors.initials: H
authors.lastname: Ohi
authors.forename: T
authors.initials: T
authors.lastname: Murata
authors.forename: T
authors.initials: T
authors.lastname: Usui
mesh_terms: D000606:Amino Sugars / Q000378:metabolism; D001667:Binding, Competitive; D002480:Cellulase / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006027:Glycosides / Q000096:biosynthesis*; D006028:Glycosphingolipids / Q000378:metabolism*; D006031:Glycosylation; D006868:Hydrolysis; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D000606:Amino Sugars; D003902:Detergents; D006027:Glycosides; D006028:Glycosphingolipids; C000458:N-acetyllactosamine; D002480:Cellulase; D007785:Lactose