pH-Dependent Conformational Changes of Concanavalin A

pH-Dependent Conformational Changes of Concanavalin A

R. Zand,
B. B. L. Agrawal*, and
I. J. Goldstein

Biophysics Research Division of the Institute of Science and Technology, The University of Michigan, Ann Arbor, Mich. 48104
Department of Biological Chemistry, The University of Michigan, Ann Arbor, Mich. 48104

Abstract

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 β 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 α helix. The pH of maximum precipitin-like activity of concanavalin A is paralleled by the pH dependence of the parameter b₀ in the Moffitt equation.