Impairment of a model peptide by oxidative stress: Thermodynamic stabilities of asparagine diamide Cα-radical foldamers

• DOI: 10.1016/j.cplett.2013.12.037
• Publication Date: 2014-01-06T18:35:47Z
• Authors: Klára Z. Gerlei; Lilla Élő; Béla Fiser; Michael C. Owen; Imre Jákli; Svend J. Knak Jensen; Imre G. Csizmadia; András Perczel; Béla Viskolcz
• Keywords: 0303 health sciences; 03 medical and health sciences; QD Chemistry / kémia

Abstract Electron structure calculations on N-acetyl asparagine N-methylamide were performed to identify the global minimum from which radicals were formed after H-abstraction by the OH radical. It was found that the radical generated by breaking the C–H bond of the α-carbon was thermodynamically the most stable one in the gas- and aqueous phases. The extended (βL and βD) backbone conformations are the most stable, but syn–syn or inverse γ-turn (γL) and γ-turn (γD) have substantial stability too. The highest energy conformers are the degenerate eL and eD foldamers. Clearly, the most stable β foldamer is the most likely intermediate for racemization.