| Autor: |
G, Pietrzyński, B, Rzeszotarska, E, Ciszak, M, Lisowski, Z, Kubica, G, Boussard |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
International journal of peptide and protein research. 48(4) |
| ISSN: |
0367-8377 |
| Popis: |
The crystal structure and solution conformation of Ac-Pro-deltaAla-NHCH3 and the solution conformation of Ac-Pro-(E)-deltaAbu-NHCH3 were investigated by X-ray diffraction method and NMR, FTIR and CD spectroscopies. Ac-Pro-deltaAla-NHCH3 adopts an extended-coil conformation in the crystalline state, with all-trans peptide bonds and the deltaAla residue being in a C5 form, phi(1)=-71.4(4), psi(1)=-16.8(4), phi(2)= -178.4(3) and psi(2)= 172.4(3) degrees. In inert solvents the peptide also assumes the C5 conformation, but a gamma-turn on the Pro residue cannot be ruled out. In these solvents Ac-Pro-(E)-deltaAbu-NHCH3 accommodates a beta(II)-turn, but a minor conformer with a nearly planar disposition of the CO-NH and C=C bonds (phi(2) approximately 0 degrees) is also present. Previous spectroscopic studies of the (Z)-substituted dehydropeptides Ac-Pro-(Z)-deltaAbu-NHCH3 and Ac-Pro-deltaVal-NHCH3 reveal that both peptides prefer a beta(II)-turn in solution. Comparison of conformations in the family of four Ac-Pro-deltaXaa-NHCH3 peptides let us formulate the following order of their tendency to adopt a beta-turn in solution: (Z)-deltaAbu(E)-deltaAbudeltaVal; deltaAla does not. None of the folded structures formed by the four compounds is stable in strongly solvating media. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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