N --> pi* Interaction and n)(pi Pauli repulsion are antagonistic for protein stability.

ABSTRACT: In many common protein secondary structures, such as alpha-, 3(10), and polyproline II helices, an n --> pi* interaction places the adjacent backbone amide carbonyl groups in close proximity to each other. This interaction, which is reminiscent of the Burgi-Dunitz trajectory, involves delocalization of the lone pairs (n) of the oxygen (O(i-1)) of a peptide bond over the antibonding orbital (pi*) of C(i)=O(i) of the subsequent peptide bond. Such a proximal arrangement of the amide carbonyl groups should be opposed by the Pauli repulsion between the lone pairs (n) of O(i-1) and the bonding orbital (pi) of C(i)=O(i). We explored the conformational effects of this Pauli repulsion by employing common peptidomimetics, wherein the n --> pi* interaction is attenuated while the Pauli repulsion is r

SUBMITTER: Jakobsche CE 

PROVIDER: S-EPMC2874455 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature