Conformational studies on polypeptides. The effect of sodium perchlorate on the conformation of poly‐ L ‐lysine and of random copolymers of L ‐lysine and L ‐phenylalanine in aqueous solution

Circular Dichroism measurements have been carried out on poly‐ L ‐lysine (PLL) and on random copolymers of lysine and phenylalanine at various p H values and in the presence of different amounts of NaClO 4 . The results indicate that either the homopolymer or the copolymers at p H conditions at which the side‐chain amino groups are fully protonated, assume the right‐handed α‐helical conformation in the presence of NaClO 4 . The results are interpreted in terms of specific binding of ClO 4 − ions on charged side‐chain amino groups.