PEPTIDE MODELS .9. A COMPLETE CONFORMATIONAL SET OF FOR-ALA-ALA-NH2 FROM AB INITO COMPUTATIONS

This paper reports the complete set of minimum energy (i.e. stable) co nformations of For-Ala-Ala-NH2 (containing three peptide bonds), compu ted by ab initio geometry optimization. A more confident structure and relative energy comparison of the 49 different relaxed geometries was possible using the HF/3-21G method as compared to empirical (force fi eld) methods. The analysis of the different conformers resulted in a u seful structure database, incorporating 30 different beta-turns, which will have some relevance to the description of peptide folding. Spect roscopic (e.g. NMR) consequences of the reported ab initio calculation s are also discussed, and a 3D-structure assignment method for protein s is provided.