The crystal structure of a Dcp-containing peptide

We have investigated the conformational preferences of a newly synthesized C-alpha,C-alpha symmetrically disubstituted glycine, namely alpha,alpha-dic yclopropylglycine (Dcp). We report here the crystal structure of a fully pr otected dipeptide containing Dcp, namely Z-Dcp'-Dcp(2)-OCH3. Both Dcp resid ues are in a folded conformation. The overall peptide structural organizati on corresponds to an alpha-pleated sheet conformation, similar to that obse rved in linear peptides made up of alternating D- and L-residues and in Z-A ib-Aib-OCH3 (Aib: alpha,alpha-dimethylglycine). These preliminary data sugg est that the Dcp could represent an alternative as molecular tool to stabil ize folded conformations. (C) 2000 John Wiley & Sons, Inc.