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Galectins are a family of mammalian beta-galactoside-binding proteins that positively and negatively regulate T cell death. Extracellular galectin-1 directly induces death of T cells and thymocytes, while intracellular galectin-3 blocks T cell death. In contrast to the antiapoptotic function of intracellular galectin-3, we demonstrate that extracellular(More)
Plant and animal lectins bind and cross-link certain multiantennary oligosaccharides, glycopeptides, and glycoproteins. This can lead to the formation of homogeneous cross-linked complexes, which may differ in their stoichiometry depending on the nature of the sugar receptor involved. As a precisely defined ligand, we have employed bovine asialofetuin(More)
This study investigates the inhibition of microtubule assembly in vitro by podophyllotoxin and its derivatives, which include in part the antitumor compounds 4'-demethylepipodophyllotoxin ethylidene beta-D-glucoside (VP-16-213) and 4'-demethylepipodophyllotoxin thenylidene beta-D-glucoside (VM-26); the cyclic ethers, cyclic sulfides, and cyclic sulfones of(More)
Many biological ligands are composed of clustered binding epitopes. However, the effects of clustered epitopes on the affinity of ligand-receptor interactions in many cases are not well understood. Clustered carbohydrate epitopes are present in naturally occurring multivalent carbohydrates and glycoproteins, which are receptors on the surface of cells.(More)
The trisaccharide 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannose, which is present in all asparagine-linked carbohydrates, was previously shown by titration microcalorimetry to bind to the lectin concanavalin A (ConA) with nearly -6 kcal mol-1 greater enthalpy change and 60-fold higher affinity than methyl-alpha-D-mannopyranoside (Mandal, D. K., Kishore, N.,(More)
We have recently demonstrated that certain oligomannose and bisected hybrid type glycopeptides and bisected complex type oligosaccharides are bivalent for binding to concanavalin A and can precipitate the lectin [Bhattacharyya, L., Ceccarini, C., Lorenzoni, P., & Brewer, C.F. (1987) J. Biol. Chem. 262, 1288-1293; Bhattacharyya, L., Haraldsson, M., & Brewer,(More)
Binding of a series of synthetic multivalent carbohydrate analogs to the Man/Glc-specific lectins concanavalin A and Dioclea grandiflora lectin was investigated by isothermal titration microcalorimetry. Dimeric analogs possessing terminal alpha-D-mannopyranoside residues, and di-, tri-, and tetrameric analogs possessing terminal 3,(More)
The concentrations of methyl glycosides, oligosaccharides, glycopeptides, and glycoproteins can be accurately determined by using calibration curves composed of the appropriate monosaccharide(s) obtained with a modified version of the colorimetric phenol-sulfuric acid method. Calibration curves of micrograms sugar vs. 490 nm for Man, Glc, or Gal are shown(More)
We have investigated the binding of a series of high affinity asparagine-linked glycopeptides, including high mannose type and a bisected hybrid type, and several related synthetic oligosaccharides, to Ca2+- Mn2+-concanavalin A (ConA), using solvent proton nuclear relaxation dispersion (NMRD) measurements. We find that binding of the glycopeptides induces a(More)