Structure of Z-L-(αMe)Phe-(L-Ala)2-OMe monohydrate

Structures of peptides from alpha-amino acids methylated at the alpha-carbon

The structural preferences of peptides (and depsipeptides) from the achiral MeAib and Hib residues, and the chiral Iva, (alpha Me) Val, (alpha Me) Leu, and (alpha Me) Phe residues, as determined by conformational energy computations, x-ray diffraction analyses, and 1H-nmr and spectroscopic studies, are reviewed and compared with literature data on Aib-containing peptides. The results obtained indicate that helical structures are preferentially adopted by peptides rich in these alpha-amino acids methylated at the alpha-carbon. Intriguing experimental findings on the impact of the chirality of Iva, (alpha Me) Val, and (alpha Me) Phe residues on helix screw sense are illustrated.

X-ray crystallography of peptides: the contributions of the Italian laboratories

The review article summarizes the most relevant solid state structural and conformational results obtained in the laboratories involved in Italy in the studies of synthetic and natural peptides by x-ray diffraction analyses. Some of the topics will include research studies carried out in other European countries, whereas in other cases studies carried out in Italy will be included in other review articles included in this volume. The review deals with peptides containing symmetrically achiral and unsymmetrically chiral C alpha,alpha-dialkylated glycine residues, peptides containing beta-alanine residues, alpha,beta-dehydroamino acid residues, and aminosuccinyl residues, peptides containing the thioamide surrogate, heterochiral peptides and several bioactive peptides systems with the proposed relationships between function and structure.