Conformational analysis of cyclized dipeptide models for specific types of beta-bends by two-dimensional nuclear Overhauser spectroscopy.
The solution conformations in DMSO-d6 of the two cyclized dipeptides, cyclo(L-alanyl-L-alanyl-epsilon-aminocaproyl) and cyclo(L-alanyl-D-alanyl-epsilon-aminocaproyl), have been analyzed by means of the two-dimensional nuclear Overhauser effect (2D-NOE). The preferred conformations for the two compounds have been deduced by comparing proton-proton distances, derived from the 2D-NOE data and relaxation-time measurements, with the corresponding distances in several possible computed low-energy conformations. The predominant conformations are a type III bend and a type II bend, respectively, for the two compounds. These conclusions agree with those deduced earlier on the basis of infrared and Raman spectra and circular dichroism measurements.
D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D010456:Peptides, Cyclic; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013816:Thermodynamics
D010456:Peptides, Cyclic; C035649:cyclo(alanylalanyl-epsilon-aminocaproyl)