Glycoconjugate Journal

, Volume 5, Issue 1, pp 75–84

Saccharide binding to three Gal/GalNAc specific lectins: Fluorescence, spectroscopic and stopped-flow kinetic studies

Authors

  • M I Khan
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • M Joginadha Swamy
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • M V Krishna Sastry
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • S Umadevi Sajjan
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • S R Patanjali
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • Prasad Rao
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • G V Swarnalatha
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • P Banerjee
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
  • A Surolia
    • Molecular Biophysics Unit, U.G.C. Centre for Advanced StudiesIndian Institute of Science
Article

DOI: 10.1007/BF01048333

Cite this article as:
Khan, M.I., Swamy, M.J., Sastry, M.V.K. et al. Glycoconjugate J (1988) 5: 75. doi:10.1007/BF01048333

Abstract

Fluorescence and stopped-flow spectrophotometric studies on three plant lectins fromPsophocarpus tetragonolobus (winged bean),Glycine max (soybean) andArtocarpus integrifolia (jack fruit) have been studied usingN-dansylgalactosamine as a fluorescent ligand. The best monosaccharide for the winged bean agglutinin I (WBA I) and soybean (SBA) is Me-αGalNAc and for jack fruit agglutinin (JFA) is Me-αGal. Examination of the percentage enhancement and association constants (1.51×106, 6.56×106 and 4.17×105 M−1 for SBA, WBA I and JFA, respectively) suggests that the combining regions of the lectins SBA and WBA I are apolar whereas that of JFA is polar. Thermodynamic parameters obtained for the binding of several monosaccharides to these lectins are enthalpically favourable. The binding of monosaccharides to these lectins suggests that the-OH groups at C-1, C-2, C-4 and C-6 in thed-galactose configuration are important loci for interaction with these lectins. An important finding is that the JFA binds specifically to Galß1-3GaINAc with much higher affinity than the other disaccharides which are structurally and topographically similar.

The results of stopped-flow spectrometry on the binding ofN-dansylgalactosamine to these lectins are consistent with a bimolecular single step mechanism. The association rate constants (2.4×105, 1.3×104, and 11.7×105 M−1 sec−1 for SBA, WBA I and JFA, respectively) obtained are several orders of magnitude slower than the ones expected for diffusion controlled reactions. The dissociation rate constants (0.2, 3.2×10−2, 83.3 sec−1 for SBA, WBA I and JFA, respectively) obtained for the dissociation ofN-dansylgalactosamine from its lectin complex are slowest for SBA and WBA I when compared with any other lectin-ligand dissociation process.

Key words

lectinsugar binding fluorescent ligand

Abbreviations

SBA

Soybean agglutinin

WBA I

Winged bean agglutinin (Basic)

JFA

Jack fruit agglutinin

PNA

Peanut agglutinin

Con A

Concanavalin A

Dansyl (Dns)

5-dimethylaminonaphthalene-I-sulphonyl

2GaINDns

N-dansylgalactosamine

dGal

2-deoxygalactose

l-Ara

l-arabinose

d-Fuc

d-fucose

l-Rha

l-rhamnose

N-acetyllactosamine

Galß4GlcNAc

melibiose

Galα6Glc

Copyright information

© Glycoconjugate Journal 1988