Structural changes in poly(D-alanine).
Investigations are reported on the possibility of the direct transformations from alpha-helices to beta-sheets in poly(D-alanine) by heating and the immersion into formic acid, and were concluded that intrahelical hydrogen bonds in the alpha-helix were stable, while interhelical interactions in the alpha-helix crystal were weakened, and beta-sheets did not transform directly from alpha-helices, but grew from random coils.