title: Interaction of rice (Oryza sativa) lectin with N-acetylglucosaminides. Fluorescence studies.
abstract: The interaction of lectin isolated from rice (Oryza sativa) embryos with N-acetylglucosaminides was studied by equilibrium dialysis and fluorescence. Equilibrium dialysis with 4-methylumbelliferyl-(GlcNac)2 showed that rice lectin (Mr 38000) contains four equivalent saccharide-binding sites. Addition of the N-acetylglucosaminides GlcNac, (GlcNac)2 and (GlcNac)3 enhanced the intrinsic fluorescence of rice lectin and this was accompanied by a 10nm blue-shift of its maximum fluorescence with (GlcNac)2 and (GlcNac)3. These changes in intensity allowed determination of the association constants, which increased with the number of saccharide units: at 20 degrees C, Ka = (1.3 +/- 0.1) X 10(3), (5.1 +/- 0.4) X 10(4) and (2.6 +/- 0.1) X 10(5) M-1 for GlcNac, (GlcNac)2 and (GlcNac)3 respectively. The binding enthalpy, delta H0, for the three glucosaminides were very low and ranged from -12.1 to -20.6 kJ X mol-1. The results are compared with those obtained with wheat-germ agglutinin, another GlcNac-specific gramineaous lectin.
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000378:metabolism*; D001665:Binding Sites; D005944:Glucosamine / Q000031:analogs & derivatives*; D007700:Kinetics; D037102:Lectins; D012275:Oryza; D037121:Plant Lectins; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics
chemical_list: D037102:Lectins; D037121:Plant Lectins; C040599:rice lectin; D005944:Glucosamine; D000117:Acetylglucosamine