pH-dependent conformational changes of concanavalin A.

The pH dependence of the conformation of concanavalin A has been studied by means of optical rotatory dispersion and circular dichroism spectroscopy. At pH 2.9, 5.0, and 7.0, the major contribution to organized structure appears to be the beta conformation. At pH 9.1, the conformation of concanavalin A approaches the random coil or unordered form. No evidence could be found for the presence of any significant amount of alpha helix. The pH of maximum precipitin-like activity of concanavalin A is paralleled by the pH dependence of the parameter b(0) in the Moffitt equation.