13c nmr reveals no evidence of n？π interactions in proteins13 c核磁共振显示没有证据表明n π相互作用的蛋白质.pdfVIP

13C NMR Reveals No Evidence of n 2p* Interactions in Proteins Bradley Worley, Georgia Richard, Gerard S. Harbison, Robert Powers* Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America Abstract An n {p interaction between neighboring carbonyl groups has been postulated to stabilize protein structures. Such an interaction would affect the 13C chemical shielding of the carbonyl groups, whose paramagnetic component is dominated by n {p and p {p excitations. Model compound calculations indicate that both the interaction energetics and the chemical shielding of the carbonyl group are instead dominated by a classical dipole-dipole interaction. A set of high- resolution protein structures with associated carbonyl 13C chemical shift assignments verifies this correlation and provides no evidence for an inter-carbonyl n {p interaction. Citation: Worley B, Richard G, Harbison GS, Powers R (2012) 13C NMR Reveals No Evidence of n 2p* Interactions in Proteins. PLoS ONE 7(8): e42075. doi:10.1371/ journal.pone.0042075 ´ Editor: Daniel Monleon, Instituto de Investigacion Sanitaria INCLIVA, Spain Received February 4, 2012; Accepted July 2, 2012; Published August 2, 2012 Copyright: 2012 Worley et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported in part from the National Institute of Allergy and Infectious Diseases (grant number R21AI081154) to RP. The research was performed in facilities renovated with support from the