Ronald T. Raines, the Firmenich Professor of Chemistry at the Massachusetts Institute of Technology, is the 2019 McNelis Distinguished Lecturer in Chemistry at NYU. In addition to the named lecture to take place the following day, he will deliver this seminar geared for a student audience, entitled, "The Not-So-Lonely Lone Pairs of the Peptide Bond Oxygen." Hosted by Paramjit Arora.
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Abstract: In the alpha‑helices and beta-sheets that dominate protein structure, a lone pair of electrons on the peptide-bond oxygen accepts a hydrogen bond. We have discovered that the other electron pair on that oxygen also participates in meaningful interactions in both of these architectural elements. In an alpha-helix, this interaction is an O···C=O n-to-pi* interaction with the next carbonyl group in the main chain. In a beta-sheet, this interaction is an O···H–N hydrogen bond within the residue. Both of these interactions entail the formation of 5-membered rings and involve significant overlap of non-bonding and anti-bonding orbitals. Whereas the canonical hydrogen bonds engage the s orbital of the oxygen, the n-to-pi* interaction and “C5” hydrogen bond engage a p orbital that is orthogonal to the C=O bond. These latter interactions, which are enhanced by the orbital demixing that accompanies canonical hydrogen-bond formation, have important consequences for both protein stability and enzymatic catalysis.
In addition to this seminar, Ron Raines will deliver The McNelis Distinguished Lecture in Chemistry on Friday, April 26 at 11:00 a.m. in Jurow Lecture Hall (room 101 Silver), entitled, "Molecular Cloaks and Daggers: Expanding the Pharmacopeia."