Binding of N-dansylgalactosamine to the lectin from Erythrina cristagalli as followed by stopped-flow and pressure-jump relaxation kinetics.
The binding kinetics of N-dansylgalactosamine to the lectin from Erythrina cristagalli have been studied using stopped-flow and pressure-jump chemical relaxation by monitoring ligand fluorescence. Both methods gave results which are consistent with a simple bimolecular association reaction. The association rate constant, k + 1 = 4.8 X 10(4) M-1 s-1, is far too low to be controlled by diffusion; the dissociation rate is 0.4-0.66 s-1, depending upon the method of determination and the experimental conditions. Identical reaction-rate parameters were obtained at pH 7.3, where soluble aggregates can be present in the lectin solution and at pH 4.7 where such aggregates are absent. The slow rates of carbohydrate binding seem to be characteristic for most lectins and lend support to the idea that they are evolutionary related and have structurally similar binding sites. Analysis of the relaxation amplitudes of the pressure-jump experiments yielded a molar reaction volume change, delta V0, upon binding of +7 ml/mol. This volume change can be caused by desolvation of the ligand upon binding.
D001665:Binding Sites; D003619:Dansyl Compounds / Q000378:metabolism*; D004895:Erythrina; D005688:Galactosamine / Q000031:analogs & derivatives* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D037102:Lectins / Q000032:analysis*; D008433:Mathematics; D037121:Plant Lectins; D010946:Plants, Medicinal; D013050:Spectrometry, Fluorescence
D003619:Dansyl Compounds; D037102:Lectins; D037121:Plant Lectins; C045629:erythrina lectin; D005688:Galactosamine; C041456:dansylgalactosamine