Our primary objective is to obtain experimental values of the Zimm-Bragg growth and nucleation parameters, s and sigma, for each of the 20 naturally occurring amino acids, in water and in organic solvents. These parameters will characterize, in a quantitative way, the tendency of each amino acid residue in a protein to adopt an alpha-helical or a coil conformation, in polar and nonpolar media. These experimental values of s and sigma will then be used to provide information about the conformational properties of proteins. The parameters themselves will be obtained by studying the helix-coil transition of random copolymers of two types of amino acid, a host (whose s and sigma values are known) and a guest (whose s and sigma values are to be determined). Random copolymers of varying chain length and of varying composition of the host and guest residues will be synthesized and fractionated; melting date will be obtained for these fractions, in both water (at high and low pH) and organic solvents. Appropriate theory is available for analyzing such experimental data. We will also examine the acid-base equilibria, in those copolymers containing amino acids with ionizable side chains, to obtain direct information on the influence of near-neighbor interaction on pK's. Similar studies are planned to determine the intrinsic tendencies of the 20 naturally occurring amino acids to form beta structures in water.