SPECIFICITY OF ZINC-BINDING TO MYELIN BASIC-PROTEIN

Zn2+ appears to stabilize the myelin sheath but the mechanism of this effect is unknown. In a previous report we have shown that zinc binds to CNS myelin basic protein (MBP) in the presence of phosphate and thi s results in MBP aggregation. For this paper we used a solid phase zin c blotting assay to identify which myelin proteins bind zinc. MBP and a 58 kDa band were found to be the major targets of Zn-65 binding. Mor eover, using fluorescence, light scattering and electron microscopy we investigated the binding of zinc and other cations to purified MBP in solution. Among the cations tested for their ability to interfere wit h the binding of zinc, the most effective were cadmium, mercury and co pper, but only cadmium and mercury increased the scattering intensity, whereas MBP aggregation was not inhibited by copper ions. Thus, the e ffect of zinc on the formation of MBP clusters seems to be specific.