Heat capacities of solid copoly(amino acid)s

Abstract

Abstract Recently heat capacities C p of poly(amino acid)s of all naturally occurring amino acids have been determined. In a second step the heat capacities of four copoly(amino acid) s are studied in this research. Poly( L ‐lysine · HBr‐alanine), poly( L ‐Lysine · HBr‐phenylalanine), poly(sodium‐ L ‐glutamate‐tyrosine), and poly( L ‐proline‐glycine‐proline) heat capacities are measured by differential scanning calorimetry in the temperature range 230–390 K. This is followed by an analysis using approximate group vibrations and fitting the C p contributions of the skeletal vibrations of the corresponding homopolymers to a two‐parameter Tarasov function. Good agreement is found between experiment and calculation. Predictions of heat capacities based on homopoly(amino acid)s are thus expected to be possible for all polypeptides, and enthalpies, entropies, and Gibbs functions for the solid state can be derived.