Year: 2019
Type: article
Abstract: Andrew Marcus opened a discussion of the introductory lecture by Majed Chergui: My question pertains to the theoretical interpretation of the interesting time-resolved circular dichroism (CD) experiments on DNA that you presented.The determination of nucleic acid base conformation from CD data is a fairly complex and challenging problem, which has been studied for many years.In an oligonucleotide with many bases, the CD spectrum depends on the numerous non-degenerate couplings between the many transition dipole moments of the bases, which in turn depends on their relative distances and orientations (i.e.base conformation).In general, there is no unique mapping between a given CD spectrum and a specic oligonucleotide conformation.How might this issue be addressed for the structural interpretation of time-resolved CD experiments on oligonucleotides?Majed Chergui responded: This is a very good question and I agree with you that the modelling of CD spectra is far from trivial for systems like nucleic acid bases or even peptides.What I showed in my talk aimed at starting to resolve this problem, at least in the case of peptide chains, using thioamide substitution.We investigated a dipeptide whose two carbonyl oxygen atoms were replaced by sulfur, so that the strong lowest-lying pi-pi* transitions are shied to the red.This not only brings them in the range of our time-resolved CD set-up but more importantly, it offers a site specic labelling of the peptidic chains.Similar substitutions are possible with DNA strands and they are already used in either uorescence or CD studies, e.g.2-aminopurine dinucleotides, which we are planning to use.From a more general perspective, there are still huge challenges to be overcome in order to make time-resolved CD a reliable and easy to implement method:This
Source: Faraday Discussions
DOI: 10.1039/c9fd90027f
Authors: Shuming Bai, Vytautas Balevicius, Eric Bittner, Yuan-Chung Cheng, Majed Chergui, Jeffrey Cina, Natércia das Neves Rodrigues, Animesh Datta, Jahan Dawlaty, Amro Dodin, Benjamin Fingerhut, Graham Fleming, Naomi Ginsberg, Sharon Hammes-Schiffer, Vanessa Huxter, Bern Kohler, Yumin Lee, Graham Leggett, Andrew Marcus, Karen Morenz, Jennifer Ogilvie, Alexandra Olaya-Castro, Thomas A. A. Oliver, Minjung Son, Yin Song, Vasilios Stavros
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2954897563