Subject(s)
Aneurysm, False/therapy , Angiography , Cholecystitis/complications , Cystic Duct/blood supply , Embolization, Therapeutic/methods , Emergencies , Gallbladder/blood supply , Image Enhancement , Tomography, X-Ray Computed , Aged , Aneurysm, False/diagnosis , Cholecystitis/diagnosis , Follow-Up Studies , Humans , MaleABSTRACT
The free Val-Pro-Gly-Gly tetrapeptide belonging to the Proline-rich sequences of elastin has been studied both theoretically and experimentally. The molecular modelisation was carried out using AM1 and ab initio quantum computations while the conformation in solution was ascertained by circular dichroism spectroscopy performed on the synthesized tetrapeptide. Experimental and theoretical investigations lead to the conclusion that the most probable structure is constituted by a type II beta-turn.
Subject(s)
Elastin/chemistry , Models, Molecular , Oligopeptides/chemistry , Protein Conformation , Glycine , Proline , ValineABSTRACT
The conformational analysis and electrostatic properties of the monomeric sequence V-G-G-V-G of the glycine-rich regions of elastin is presented with the aim of explaining NMR and CD experimental results. On the basis of the molecular model NH+3-V-G-G-V-G-COO, Gaussian 92 quantum-molecular computations were performed by using principally an ab initio method at the 3-21G level and AM1. The occurrence of local secondary structures and of beta I, beta II, beta II' and VIa turns is discussed. Our results clearly demonstrate that the transconformations beta I-->half turn (which was invoked to explain experimental results) and beta I-->beta II' are theoretically allowed.
