title: Rigidified multivalent lactose molecules and their interactions with mammalian galectins: a route to selective inhibitors.
abstract: New and rigid multivalent lactose molecules were prepared. The structures contain lactose-2-aminothiazoline units at the periphery that were formed from a cyclisation of the thiourea sulphur onto the triple bond of the spacer. The lactosides were evaluated as inhibitors against lectin binding in a solid phase inhibition assay. In this assay the glycoprotein asialofetuin was immobilized onto the surface of microtiter plate wells, mimicking cell surface presentation, while mammalian galectins-1, -3 or -5 were in solution. Between the three galectins, the folding pattern and sequence are closely related but the topology of presentation of the carbohydrate recognition domains differs. Strong multivalency effects were observed for the tetravalent lactoside in the inhibition of galectin-3 binding with enhancements of almost 4300-fold compared to lactose. Remarkable selectivity was obtained in the inhibition since relative potencies of the tetravalent lactoside with the proto type galectins-1 and -5 did not exceed a factor of 143 relative to lactose. The binding of the lactosides to galectin-3 was also studied by fluorescence spectroscopy with all components in solution. These studies showed no multivalency effects in the inherent binding affinities.
authors.affiliation: Department of Medicinal Chemistry, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, PO Box 80082, NL-3508 TB Utrecht, The Netherlands.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vrasidas
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Paola
authors.initials: P
authors.lastname: Valentini
authors.forename: Corina
authors.initials: C
authors.lastname: Böck
authors.forename: Martin
authors.initials: M
authors.lastname: Lensch
authors.forename: Herbert
authors.initials: H
authors.lastname: Kaltner
authors.forename: Rob M
authors.initials: RM
authors.lastname: Liskamp
authors.forename: Hans-J
authors.initials: HJ
authors.lastname: Gabius
authors.forename: Roland J
authors.initials: RJ
authors.lastname: Pieters
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D037161:Galectins / Q000737:chemistry*; D007785:Lactose / Q000737:chemistry*; D008322:Mammals; D008969:Molecular Sequence Data; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D037161:Galectins; D007785:Lactose