HELIX SENSE IN POLY(BETA-ALKYL ALPHA-L-ASPARTATE)S

Energy calculations have been carried out for several oligomeric pepti des derived from beta-methyl alpha-L-aspartate, beta-ethyl alpha-L-asp artate, and beta-propyl alpha-L-aspartate. Self-consistent field calcu lations have revealed the favored helix sense for such compounds, whil e self-consistent reaction-field calculations have indicated the influ ence exerted by the solvent on their conformational preferences. The r ight-handed alpha-helix was found to be the most favored conformation for both the ethyl and propyl derivatives. On the contrary, the confor mation preferred by the methyl derivatives was the left-handed omega-h elix. The influence of the interactions between the amide and ester gr oups on the helical sense preferences displayed by these compounds are discussed.