title: 1-O-Acetyl-beta-D-galactopyranose: a novel substrate for the transglycosylation reaction catalyzed by the beta-galactosidase from Penicillium sp.
abstract: 1-O-Acetyl-beta-D-galactopyranose (AcGal), a new substrate for beta-galactosidase, was synthesized in a stereoselective manner by the trichloroacetimidate procedure. Kinetic parameters (K(M) and k(cat)) for the hydrolysis of 1-O-acetyl-beta-D-galactopyranose catalyzed by the beta-D-galactosidase from Penicillium sp. were compared with similar characteristics for a number of natural and synthetic substrates. The value for k(cat) in the hydrolysis of AcGal was three orders of magnitude greater than for other known substrates. The beta-galactosidase hydrolyzes AcGal with retention of anomeric configuration. The transglycosylation activity of the beta-D-galactosidase in the reaction of AcGal and methyl beta-D-galactopyranoside (1) as substrates was investigated by 1H NMR spectroscopy and HPLC techniques. The transglycosylation product using AcGal as a substrate was beta-D-galactopyranosyl-(1-->6)-1-O-acetyl-beta-D-galactopyranose (with a yield of approximately 70%). In the case of 1 as a substrate, the main transglycosylation product was methyl beta-D-galactopyranosyl-(1-->6)-beta-D-galactopyranoside. Methyl beta-D-galactopyranosyl-(1-->3)-beta-D-galactopyranoside was found to be minor product in the latter reaction.
authors.affiliation: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky av. 47, Moscow 119991, Russia.
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Zinin
authors.forename: Elena V
authors.initials: EV
authors.lastname: Eneyskaya
authors.forename: Konstantin A
authors.initials: KA
authors.lastname: Shabalin
authors.forename: Anna A
authors.initials: AA
authors.lastname: Kulminskaya
authors.forename: Sergei M
authors.initials: SM
authors.lastname: Shishlyannikov
authors.forename: Kirill N
authors.initials: KN
authors.lastname: Neustroev
mesh_terms: D005697:Galactosides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D008756:Methylgalactosides / Q000378:metabolism; D009598:Nitrophenylgalactosides / Q000378:metabolism; D010407:Penicillium / Q000201:enzymology*; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: C464595:1-O-acetyl-galactopyranose; D005697:Galactosides; D008756:Methylgalactosides; C031552:methyl beta-galactoside; D009598:Nitrophenylgalactosides; D001616:beta-Galactosidase; D007785:Lactose