Magnesium as a natural substitute for manganese in concanavalin A and other lectins.
Addition of magnesium to apo-concanavalin A in the presence of calcium was shown by ultraviolet difference spectroscopy to generate a holoprotein spectroscopically identical to the MnCa-holoprotein. The MgCa- and MnCa-forms bound equally strongly to Sephadex G-75. In kinetic experiments, the binding of Mg2+ was much slower than Mn2+ binding; Kd for Mg2+ was estimated as 7.4 mM. The combined Mg2+ and Mn2+ contents of 10 lectins specific for D-galactose or N-acetyl-D-galactosamine were each close to one atom per subunit, suggesting occupancy of the Mn2+ site by Mg2+ is common in plant lectins.
D055598:Chemical Phenomena; D002621:Chemistry; D003208:Concanavalin A; D007700:Kinetics; D037102:Lectins; D008274:Magnesium / Q000302:isolation & purification*; D008345:Manganese / Q000302:isolation & purification*; D011485:Protein Binding; D013056:Spectrophotometry, Ultraviolet
D037102:Lectins; D003208:Concanavalin A; D008345:Manganese; D008274:Magnesium