Binding of N-dansylgalactosamine to winged-bean tuber lectin: studies by fluorescence quenching titrations.
The winged-bean tuber lectin binds to N-dansyl(5-dimethylaminonaphthalene-1-sulphonic acid)galactosamine, leading to a 12.5-fold increase in dansyl fluorescence with a concomitant 25 nm blue-shift in the emission maximum. The enhancement of fluorescence intensity was completely reversed by the addition of methyl alpha-galactopyranoside. The lectin has two binding sites per molecule for this fluorescent sugar and an association constant of 2.59.10(5) M-1 at 25 degrees C. The binding of N-dansylgalactosamine to the lectin shows that it can accommodate a large hydrophobic substituent on the C-2 carbon of D-galactose. Studies with other sugars indicate that a hydrophobic substituent with alpha-conformation at the anomeric position increases the affinity of binding. The C-4 and C-6 hydroxyl groups are also critical for sugar binding to this lectin.
Shet
M S
MS
Department of Chemistry, Karnatak University, Dharwad, India.
Madaiah
M
M
Khan
M I
MI
D001665:Binding Sites; D050260:Carbohydrate Metabolism; D003619:Dansyl Compounds / Q000378:metabolism*; D005454:Fluorescence Polarization; D005688:Galactosamine / Q000031:analogs & derivatives* / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D037102:Lectins / Q000378:metabolism*; D037121:Plant Lectins; D011485:Protein Binding
D003619:Dansyl Compounds; D006023:Glycoproteins; D037102:Lectins; D037121:Plant Lectins; C049304:winged bean lectin; D005688:Galactosamine; C041456:dansylgalactosamine