Conformations at local energy minimums for gramicidin S: optical calculations.

Energy minimization techniques applied to an arbitrary peptide primary sequence result in a still large number of hypothetical structures of similar energy. Optical activity calculations can, in principle, be used to screen the low-energy conformations. Those conformations which yield a spectrum different from the observed spectrum by a factor greater than the current reliability of the calculation can be excluded. The method is applied to gramicidin S.