期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1971
卷号：68
期号：10
页码：2468-2471
DOI：10.1073/pnas.68.10.2468
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Conformational energies, consisting of nonbonded and electrostatic interactions, have been calculated for poly(L-proline) I and II helices, of six-residues length, with a water molecule hydrogen-bonded to each imide group. For polyproline I, the Traub-Shmueli prolyl-ring geometry was used, whereas for polyproline II, calculations were done for the 2 ring geometries of Leung and Marsh and, in some cases, for the several ring geometries of Ramachandran, et al. The chain torsion angles {omega}(N-C') and {Psi}(C[α]-C') were varied, as were the two angles that specify the orientations of the water molecules. By summation over the latter, it was possible to calculate a free energy at each {omega
