title: Thiogalactopyranosides are resistant to hydrolysis by α-galactosidases.
abstract: Fluorescently tagged glycosides containing terminal α(1→3) and α(1→4)-linked thiogalactopyranosides have been prepared and tested for resistance to hydrolysis by α-galactosidases. Eight fluorescent glycosides containing either galactose or 5-thiogalactose as the terminal sugar were enzymatically synthesized using galactosyltransferases, with lactosyl glycosides as acceptors and UDP-galactose or UDP-5'-thiogalactose, respectively, as donors. The glycosides were incubated with human α-galactosidase A (CAZy family GH27, a retaining glycosidase), Bacteroides fragilis α-1,3-galactosidase (GH110, an inverting glycosidase), or homogenates of MCF-7 human breast cancer cells or NG108-15 rat glioma cells. Substrate hydrolysis was monitored by capillary electrophoresis with fluorescence detection. All compounds containing terminal O-galactose were readily degraded. Their 5-thiogalactose counterparts were resistant to hydrolysis by human α-galactosidase A and the enzymes present in the cell extracts. B. fragilis α-1,3-galactosidase hydrolyzed both thio- and O-galactoside substrates; however, the thiogalactosides were hydrolyzed at only 1-3 % of the rate of O-galactosides. The hydrolytic resistance of 5-thiogalactose was also confirmed by an in vivo study using cells in culture. The results suggest that 5-thiogalactosides may be useful tools for the study of anabolic pathways in cell extracts or in single cells.
authors: Carlsberg Laboratory, Gamle Carlsberg Vej 10, 1799 Copenhagen V, Denmark.
authors: Dietlind
authors: D
authors: Adlercreutz
authors: Yayoi
authors: Y
authors: Yoshimura
authors: Karin
authors: K
authors: Mannerstedt
authors: Warren W
authors: WW
authors: Wakarchuk
authors: Eric P
authors: EP
authors: Bennett
authors: Norman J
authors: NJ
authors: Dovichi
authors: Ole
authors: O
authors: Hindsgaul
authors: Monica M
authors: MM
authors: Palcic
mesh_terms: D000818:Animals; D001441:Bacteroides fragilis / Q000201:enzymology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D006868:Hydrolysis; D015394:Molecular Structure; D051381:Rats; D013862:Thiogalactosides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000519:alpha-Galactosidase / Q000378:metabolism*
chemical_list: D013862:Thiogalactosides; D000519:alpha-Galactosidase