Conformational studies of proline-, thiaproline- and dimethylsilaproline-containing diketopiperazines.
As proline plays an important role in biologically active peptides, many analogues of this residue have been developed to modulate the proportion of cis and trans conformers. A correlation between the pyrrolidine ring shape and structural properties of proline has been established. Diketopiperazine (DKP) is the model of choice to study the influence of the proline ring modification. In this contribution, cyclo(Gly-Pro) and two analogues cyclo(Sip-Pro) and cyclo(Thz-Pro) have been studied with proton NMR. We showed that both analogues with heteroatoms in gamma position, silicon and sulfur respectively, display a more rigid five-member ring. The usual flexibility of proline ring is restrained in both cases and only the two C(beta)-exo and C(beta)-endo conformations are observed.
Cavelier
Florine
F
Laboratoire des Aminoacides, Peptides et Protéines, UMR-CNRS 5810, Université Montpellier II, CC19-34095 Montpellier Cedex 05, France. florine@univ-montp2.fr
Marchand
Damien
D
Mbassi
Patrick
P
Martinez
Jean
J
Marraud
Michel
M
D054659:Diketopiperazines; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D017646:Organosilicon Compounds / Q000737:chemistry; D010879:Piperazines / Q000737:chemistry*; D011392:Proline / Q000031:analogs & derivatives / Q000737:chemistry*; D011487:Protein Conformation; D053778:Thiazolidines / Q000737:chemistry*
D054659:Diketopiperazines; D017646:Organosilicon Compounds; D010879:Piperazines; D053778:Thiazolidines; C455420:silaproline; D011392:Proline; C003438:thiazolidine-4-carboxylic acid