Conformations of "Alternating" Sequential Polypeptides in Solution

Abstract

Spectroscopic studies of alternating polypeptides, prepared by polymerizing dipeptides containing one l and one d residue, indicate that in helicogenic solvents they adopt conformations with properties different from those of the normal a helix. The properties of such polypeptides in which polymerization has been accompanied by appreciable racemization are similar to those of poly(L-aspartic esters), and a distorted type of a helix is suggested; when racemization is negligible a new conformation, the nature of which is uncertain, appears to be formed. This paper is concerned primarily with the conformations adopted in solution by "alternating" sequential polypeptides of the type H-f AB^-"OH, where A and B are amino acid residues which give rise to poly(amino acids), HA"OH and HB"OH, with -helical conformations of opposite sense