THEORETICAL STRUCTURE INVESTIGATIONS OF N-ACETYL-L-PROLINE AMIDE

The potential energy surface of N-acetyl-L-proline amide has been inve stigated via RHF, AM1, and PM3 calculations. The results show signific ant differences between these methods: seven local minima can be found with RHF, three with AM1, 17 with PM3. The conformation of the RHF/6- 31G global minimum corresponds to the gamma-turn structure of polypep tides. In contrast to this, the proline conformer that participates in the formation of ten-membered beta-turns in peptide chains has a rela tively high energy in the dipeptide.