The crystal structure of a Dcp-containing peptide.

We have investigated the conformational preferences of a newly synthesized C(alpha,alpha) symmetrically disubstituted glycine, namely alpha,alpha-dicyclopropylglycine (Dcp). We report here the crystal structure of a fully protected dipeptide containing Dcp, namely Z-Dcp(1)-Dcp(2)-OCH(3). Both Dcp residues are in a folded conformation. The overall peptide structural organization corresponds to an alpha-pleated sheet conformation, similar to that observed in linear peptides made up of alternating D- and L-residues and in Z-Aib-Aib-OCH(3) (Aib: alpha,alpha-dimethylglycine). These preliminary data suggest that the Dcp could represent an alternative as molecular tool to stabilize folded conformations. Copyright 2000 John Wiley & Sons, Inc.