Helical screw-sense preferences of peptides based on chiral, Cα-tetrasubstituted α-amino acids.

摘要: The preferred helical screw senses of chiral α-amino acids with a C(α)-tetrasubstituted α-carbon atom, as determined in the crystal state by X-ray diffraction analyses on derivatives and peptides, are reviewed. This survey covers C(α)-methylated C(α)-ethylated acids, well cyclized α-carbon, including those characterized combination lack chirality at either side-chain or axial chirality. Although, general, show less pronounced bias toward single sense than their proteinogenic (C(α)-trisubstituted) counterparts, our analysis highlights significant differences terms magnitude direction such among various sub-families residues, between individual amino within each sub-family well. experimental findings can be rationalized, least part, basis steric considerations.