Solvent Proton Magnetic Relaxation Dispersion in Solutions of Concanavalin A

摘要: Abstract Concanavalin A, a protein isolated from jack beans, exhibits several important biological properties, all of which are related to its ability bind and precipitate specific polysaccharides. Concanavalin A is dimer at pH 5.6, has one transition-metal calcium-ion binding site per monomer unit molecular weight 27,000. Both metal-ion sites must be occupied for the active. It interest determine role transition metal ion in relationship sugar activity protein. We report magnetic field temperature dependences spin-lattice relaxation rates solvent protons aqueous solutions zinc manganese derivatives influence monosaccharide on these rates. The results leastsquares fit data theory, with five adjustable parameters, indicate that there rapidly exchanging water molecule ligand Mn2+ ion, residence lifetime 2.5 μsec 25°, 0.27 nm (2.7 A) ion. We find low fields (proton Larmor frequencies below about 10 MHz), correlation time dipolar interaction between electronic spin moment τS moment, but higher determined by Brownian rotational tumbling protein, because substantial variation field. Monosaccharide little effect protons, result indicates sugars do not directly