title: Synthesis of novel galactose containing chemicals by beta-galactosidase from Enterobacter cloacae B5.
abstract: The beta-galactosidase from Enterobacter cloacae B5 was employed to synthesize novel galactose containing chemicals (GCCs) using mannitol, sorbose, and salicin as acceptors in the presence of o-nitrophenyl-beta-d-galactopyranoside (oNPGal) as donor. The influences of the process parameters on GCC synthesis using mannitol as an acceptor, including effects of variations in initial substrate concentration, reaction time, and temperature, were studied in detail. The mannitol derivative reached a yield of 14.6% when the enzyme was used in the presence of 30 mM oNPGal and 60mM mannitol at 50 degrees C for 10 min. The sorbose and salicin derivatives reached yields of 19.4% and 25.2%, respectively, under the same conditions except for acceptor concentrations. Through analysis of ESI-MS and NMR spectroscopy, the three derivatives were identified to be beta-D-galactopyranosyl-(1-->1')-D-mannitol, beta-D-galactopyranosyl-(1-->1')-l-sorbose, and 2-(hydroxymethyl) phenyl beta-D-galactopyranosyl-(1-->6')-beta-D-glucopyranoside.
authors.affiliation: State Key Lab of Microbial Technology, Shandong University, Jinan 250100, PR China.
authors.forename: Lili
authors.initials: L
authors.lastname: Lu
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
authors.forename: Guofeng
authors.initials: G
authors.lastname: Gu
authors.forename: Lan
authors.initials: L
authors.lastname: Jin
authors.forename: Min
authors.initials: M
authors.lastname: Xiao
authors.forename: Fengshan
authors.initials: F
authors.lastname: Wang
mesh_terms: D002851:Chromatography, High Pressure Liquid; D016972:Enterobacter cloacae / Q000201:enzymology*; D005690:Galactose / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D001616:beta-Galactosidase; D005690:Galactose