Ab initio calculations on large molecules using molecular fragments. Evidence of hydrogen bonding in polypeptides of glycine

Ab initio calculations on di-, tri-, tetra-, and pentapeptides of glycine in various conformations are reported. Hydrogen bonding is observed as an important stabilizing force in alpha-helical conformations. These studies on polypeptides of glycine of reasonable size show for the first time that the forces acting to stabilize polypeptide conformations can be extracted directly from theoretical studies, without prior postulation of their existence or need for concern that neglect or approximation of various integrals may have biased the results.