Helix-coil transition in multicomponent random copolypeptides in water. 2. Application to random copolymers of (hydroxybutyl)-L-glutamine, L-phenylalanine, and L-lysine

Water-soluble three-component random copolymers of N super(5)-(4-hydroxybutyl)-L-glutamine, L-phenylalanine, and L-lysine were synthesized, fractionated, and characterized. The thermally induced helix-coil transitions of the fractions in water were determined by optical rotatory dispersion measurements, and the melting behavior was analyzed with the theory reported in the preceding paper. The validity of the assumption that the statistical weights of a residue depend on the kind of residue but not on those of its neighbors has been confirmed even for this ternary copolypeptide containing a cationic residue (Lys) as one of its components.