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.

Probing multivalent carbohydrate–lectin interactions by an enzyme-linked lectin assay employing covalently immobilized carbohydrates

“…Toone et al, for example, compared a range of competitive and non-competitive binding assays, including ELLA, hemagglutination inhibition, and isothermal titration microcalorimetry 32 and Pieters et al studied multivalent galectin ligands by a solid-phase inhibition assay and fluorescence titrations in solution. 52 There are also few reports that show that the use of ELLA with different matrices can lead to different relative inhibitory potencies. 33,53 This phenomenon, however, is not well understood.…”

Galectin-1 Interacts with the α5β1 Fibronectin Receptor to Restrict Carcinoma Cell Growth via Induction of p21 and p27

“…B, nuclear extracts from HT-29␣5 cells treated with Gal-1 or vehicle for the indicated time periods were incubated with 32 Plabeled Ϫ555/Ϫ512 oligonucleotide, and Sp1/ Sp3-DNA complexes were detected in gel shift assays (lanes 16 -22). As controls, aliquots from the same nuclear extracts were incubated with the 32 P-labeled CAGA boxes-containing oligonucleotide and competed with 100-fold molar excess of cold oligonucleotide to ensure specificity (lanes [23][24][25]. Experiments at each condition were repeated at least three times from independently prepared nuclear extracts; representative gels are shown.…”

“…Purification and Labeling of Galectins-Galectins-1, -3, and -5 (human homodimeric prototype Gal-1, murine chimera-type galectin-3, and rat monomeric prototype galectin-5) were purified after recombinant production by affinity chromatography on Sepharose 4B to which lactose had been covalently attached via divinyl sulfone activation, and biotinylation was performed under activity-preserving conditions as described (4,22,23). All galectins were routinely checked for purity by one-and two-dimensional gel electrophoresis under reducing and denaturing conditions, gel filtration, and nanoelectrospray ionization mass spectrometry as well as for activity by hemagglutination and solid phase assays as described (24 -26).…”

Lanthanide(III) Complexes of DOTA–Glycoconjugates: A Potential New Class of Lectin‐Mediated Medical Imaging Agents

“…In this respect, the relative orientation and spacing of the carbohydrate residues in the glycoconjugate in relation to the distribution of the Carbohydrate Recognition Domains (CRDs) on the lectins is of fundamental importance. [18,19] The hepatocyte cells on liver express lectins that recognize terminal β-galactosyl residues on desilylated glycoproteinsasialoglycoprotein receptor (ASGPR). [20] The targeting of endogenous lectins for drug delivery is an appealing concept.…”