MM2 study on the conformation of N-acetyl-L-amino acid N′-methylamides with aliphatic side chain and their Nα-methyl derivatives

✍ Scribed by Jan Hlaváček; Václav Matějka; Petr C̆ársky

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 856 KB
• Volume: 12
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540120707

✦ Synopsis

Abstract

φ – ψ maps have been calculated by the MM2(87) potential for the N^α^‐acetyl derivatives of Gly, Ala, Val, and Tle methylamides and their N^α^‐methyl substituted derivatives to interpret the ^1^H NMR and CD spectra of these compounds. From the critical examination of the available theoretical and experimental evidence it follows that in the series of N^α^ unsubstituted Ala, Val, and Tle derivatives the importance of the second lowest energy conformation (C~5~) is increased and that eventually it becomes the lowest energy conformation instead of C. With the N^α^‐methyl substituted Ala and Val derivatives, the lowest energy conformation seems to be C. Performance of MM2(87) was tested for the φ – ψ map of the Ala derivative by comparing it with other theoretical data available in the literature.