EXTENDED HUCKEL CALCULATIONS ON POLYPEPTIDE CHAINS .I. ALPHA HELIX

Extended Hückel molecular orbital calculations on four and five peptide units of polyglycine demonstrate for the first time that the α helix conformation yields a minimum for the total ground state orbital molecular energy εT. There is an increased stabilization energy per peptide unit particularly at the a helix conformation as we increase the number of peptide units from four to five which partly reflects the formation of the additional hydrogen bond. © 1969 Springer-Verlag.