Peptide mimicry employing a combination of aza-amino acyl proline and indolizidinone residues has been used to develop allosteric modulators of the prostaglandin F2α receptor. The systematic study of the N-terminal phenylacetyl moiety and the conformation and side chain functions of the central turn dipeptide residue has demonstrated the sensitive relationships between modulator activity and topology. Examination of aza-Gly-Pro and aza-Phe-Pro analogs 2a and 2b in a murine preterm labor model featuring treatment with lipopolysaccharide demonstrated their capacity to extend significantly (>20 h) the average time of delivery offering new prototypes for delaying premature birth.

The unique abilities of homo-oligo-adamantyl peptides to adopt α- and γ-turn conformations are demonstrated by X-ray diffraction, and NMR and FT-IR absorption spectroscopies.

The bis‐functionalized diamondoid α‐amino acid 2‐aminoadamantane‐2‐carboxylic acid (Adm) has been used as the building block of four Nα‐formyl homo‐dipeptide alkylamide sequences via a solution‐phase Ugi multicomponent reaction approach. The conformers of these peptides have been determined in the crystalline state by X‐ray diffraction to distinguish the influences of the C‐terminal substituent. One of the Adm peptides folds into an open and a hydrogen‐bonded γ‐turn geometry. Moreover, 3D‐structures have been observed featuring two consecutive γ‐turns in an incipient γ‐helical structure, a significantly distorted nonhelical β‐turn, as well as an S‐shaped conformation with opposite helical screw senses. A significant topological variety is thus exhibited by the ‐Adm‐Adm‐ sequences contingent on their C‐terminal substituents, illustrating both the broad conformational potential and the need for further characterization of this sterically bulky residue in explorations of its ϕ, ψ space.