Fig. 7: Additional investigation of l-cyclo (PYPV).
From: Production of constrained L-cyclo-tetrapeptides by epimerization-resistant direct aminolysis
Structure calculations were performed in CYANA version 3.98.5. (PDB code 6DNY). a Comparation of the 1H-NMR spectra of Cyclo-(Pro-Tyr-Pro-Val) and Cyclo-(Pro-Tyr-Pro-(D)Val). A. 1H-NMR spectrum of Cyclo-(Pro-Tyr-Pro-Val), B. 1H-NMR spectrum of Cyclo-(Pro-Tyr-Pro-(D)Val), C. 13C-NMR spectrum of Cyclo-(Pro-Tyr-Pro-Val) from δ 168 to δ 174, D. 13C-NMR spectrum of Cyclo-(Pro-Tyr-Pro-(D)Val) from δ 168 to δ 174. b A. NMR ensemble overlay of 10 conformers showing the cyclic nature of the tetrapeptide Cyclo-(Pro-Tyr-Pro-Val). B. Ball and stick model of cyclo-[(L)Pro-(L)Tyr-(L)Pro-(L)Val] 1 showing cis–trans isomerization, Pro1 and Pro3 are in a cis orientation while Tyr2 and Val4 are trans. C. Electros-static surface map of 1 showing positive, 0.5 kT/e (blue), and negative, −0.5 kT/e (red), regions of the electrostatic potential, where k = Boltzmann constant, T = temperature, and e = electron charge. c Structure of 1 and cis–trans isomers of endomorphin-1 (EM-1) 17. d Accumulation of cAMP in human neuroblastoma cells (SK-N-SH) (measured using a cAMP ELISA-based colorimetric assay (Cayman, kit 581001). e Dose–response of accumulated cAMP following treatment with 10 µM Forskolin and different concentrations of 1. Column heights reported on the graph represent mean values, and error bars represent the SD.
