Interaction of linear manno-oligosaccharides with three mannose-specific bulb lectins. Comparison with mannose/glucose-binding lectins.
Three new mannose-binding lectins, isolated from daffodil (NPA), amaryllis (HHA), and snowdrop (GNA) bulbs, are capable of precipitating with a linear mannopentaose (Man alpha 1-3Man alpha 1-3Man alpha 1-3Man alpha 1-2Man). NPA and HHA reacted strongly with the mannopentaose whereas GNA gave a precipitate only at concentrations greater than 500 microM. A phosphate group at C-6 of the nonreducing terminal mannosyl group prevented precipitation in all three cases. The reduced (NaBH4) mannopentaose, Man4Man-ol, did not precipitate with GNA or NPA, but was active with HHA. This activity was lost when Man4Man-ol was converted (NaIO4 then NaBH4; mild acid hydrolysis of the reduced product) into trisaccharide derivatives. With alpha-D-Manp-OMe the three lectins gave UV difference spectra having large positive peaks at 292-293 and 283-284 nm, and a small positive peak at 275 nm, characteristic of tryptophanyl and tyrosyl residues. The association constants for the interaction with alpha-D-Manp-OMe were very low (NPA, 86; HHA, 66; and GNA, 41 M-1), but the lectins bound methyl (1----3)-alpha-mannobioside with increased affinity (K for NPA 540, for HHA 2400, and for GNA 200 M-1). The bulb lectins lack binding sites for hydrophobic ligands, as judged by their failure to interact with the fluorescent probes 8-anilino-1-napthalenesulfonic acid (ANS) and 6-p-toluidino-2-naphthalenesulfonic acid (TNS).
Kaku
H
H
Department of Biological Chemistry, University of Michigan, Ann Arbor 48109.
Goldstein
I J
IJ
D002240:Carbohydrate Sequence; D005947:Glucose / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry*; D008358:Mannose / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D037121:Plant Lectins; D010944:Plants / Q000737:chemistry*; D011971:Receptors, Immunologic / Q000737:chemistry*
D037102:Lectins; D009844:Oligosaccharides; D037121:Plant Lectins; D011971:Receptors, Immunologic; D005947:Glucose; D008358:Mannose