Force field parameters for molecular mechanical simulation of dehydroamino acid residues

✍ Scribed by Giuliano Alagona; Caterina Ghio; Claudio Pratesi

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 876 KB
• Volume: 12
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540120805

✦ Synopsis

are proposed and tested. Attention is primarily focused on dehydrophenylalanine and dehydroalanine containing peptides. The values of the parameters needed were obtained from experimental measurements available in the literature and from ad hoc quantum mechanical calculations. The selected values have subsequently been adapted and refined through molecular mechanical simulations on model compounds, such as Ac-APhe-NMe, for which it was possible to carry out STO-3G/SCF calculations to check selected points on the p,y/ conformational map, and Ac-AAla-NMe, where the comparison was carried out at the 4-31G level. The newly determined force field was then applied to Ac-APhe-Ala-APhe-NMe, whose minimal energy structures allowed us to explain the different circular dichroism behavior observed in CH,Cl, and in dioxane. Starting from two minimum energy geometries of this tripeptide, the full optimization with AM1 produced an independent guess to their stmcture and stability in good agreement with the molecular mechanical one.