title: Efficient synthesis of tyrosol galactosides by the β-galactosidase from Enterobacter cloacae B5.
abstract: In this work, the β-galactosidase from Enterobacter cloacae B5 (BgaB5) exhibited excellent transglycosylation activity toward tyrosol (p-hydroxyphenethyl alcohol) when using lactose as the glycosyl donor, generating a series of tyrosol glycosides with potential pharmacological properties. The effects of substrate concentration, temperature, pH, and reaction time on the transglycosylation reaction catalyzed by the enzyme BgaB5 were studied in detail. Three tyrosol derivatives were produced in a total high yield of 50.0% when incubating the enzyme with 250 mM tyrosol and 1000 mM lactose (pH 7.5) at 50 °C for 5 min. These derivatives were subsequently purified by column chromatography and preparative thin-layer chromatography. MS analysis of the purified compounds suggested one monogalactoside (Mr300) and two digalactoside derivatives (Mr462). The following NMR analysis further identified them to be p-hydroxyphenethyl β-D-galactopyranoside, p-hydroxyphenethyl β-D- galactopyranosyl-(1 → 3')-β-D-galactopyranoside, and p-hydroxyphenethyl β-D- galactopyranosyl-(1 → 6')-β-D-galactopyranoside, respectively. The yield of the tyrosol monogalactoside which was known to possess potent bioactivities reached 39.4%, higher than other enzymatic yields reported so far. The two digalactosides, which were expected to have potential applications for novel drug screening and discovery, were artificially obtained with 10.6% yield for the first time.
authors.affiliation: National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, 250010, People's Republic of China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Qi
authors.affiliation: National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, 250010, People's Republic of China.
authors.forename: Guofeng
authors.initials: G
authors.lastname: Gu
authors.affiliation: National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, 250010, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.affiliation: National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, 250010, People's Republic of China. minxiao@sdu.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Xiao
authors.affiliation: National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan, 250010, People's Republic of China. lililu@sdu.edu.cn.|Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China. lililu@sdu.edu.cn.
authors.forename: Lili
authors.initials: L
authors.lastname: Lu
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism*; D055162:Biocatalysis; D002855:Chromatography, Thin Layer; D016972:Enterobacter cloacae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005697:Galactosides / Q000096:biosynthesis*; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D005697:Galactosides; C557337:tyrosol galactoside; C011867:4-hydroxyphenylethanol; D001616:beta-Galactosidase; D007785:Lactose; D010626:Phenylethyl Alcohol; D005690:Galactose
keywords: Enterobacter cloacae B5; Transglycosylation; Tyrosol galactosides; β-galactosidase