Multiscale conformational dynamics probed by time‐resolved circular dichroism from seconds to picoseconds

Abstract

Time-resolved circular dichroism has been developed for a few decades to investigate rapid conformational changes in (bio)molecules. In our group, we have come up with several experimental set-ups allowing us to study piconanosecond local phenomena in molecular systems as well as much slower effects occurring in proteins and DNA in the folding processes. After an overview of the worldwide realizations in this domain, we present emblematic experiments that we have carried out, spanning time domain from picoseconds to seconds.

Recent advances in the development of ultrafast electronic circular dichroism for probing the conformational dynamics of biomolecules in solution

“…Ultrafast TRCD that measure the probe intensity changes have now gained enough maturity to allow the comprehensive studies of various chiral compounds in solution, at short time scales [18,43,44,49], with a major contribution from our team [19,[54][55][56][57]. Both direct TRCD and ellipticity measurements requires so far, for each pump-probe delay, to introduce either a modulation of the circularly polarized probe or a variable phase delay on the linearly polarized probe.…”

“…two to five orders of magnitude weaker than those of conventional transient absorption, that are prone to pump-induced artifacts [16]. Recent improvements in laser technologies and in the polarization control of ultrashort laser pulses down to the deep UV spectral domain however provides renewed opportunities for the development of new TRCD detection strategies to access the conformational changes of chiral compounds with an increased sensitivity [17][18][19][20]. In this review, we give an overview of the recent key technological advances in the development of ultrafast TRCD spectroscopy.…”

Computing the electronic circular dichroism spectrum of DNA quadruple helices of different topology: A critical test for a generalized excitonic model based on a fragment diabatization

“…Nucleic acids (NAs) are chiral species, both due to the intrinsic chirality of the sugars and the helical arrangement of the nucleobases, making electronic circular dichroism (ECD) 1 a widely used technique to characterize their structural behavior 2–8 . Among the different NA secondary structures, ECD is particularly informative for monitoring the static and dynamical behaviors of guanine quadruple helices (hereafter GQs).…”

Time-resolved circular dichroism of excitonic systems: theory and experiment on an exemplary squaraine polymer

“…33,34 Further improvements of their technique led to an experimental setup allowing them to probe conformational dynamics of several molecules in a broad ultraviolet region with fs time resolution. [35][36][37][38][39][40] Performing TRCD with broadband visible pulses is an additional challenge typically realized in either of the following measurement modalities: [41][42][43][44][45] (i) an ellipsometric measurement detects the change in ellipticity of the probe beam aer it passed the chiral sample; (ii) the differential absorption method detects the difference in absorption of le-and right-circularly polarized light. Generating circularly polarized broadband probe pulses is possible either using a Pockels cell or a photoelastic modulator [46][47][48][49][50] with the options to polarize a single-wavelength seed pulse which is then transformed into a white-light continuum [51][52][53] or to create circular polarization of white-light continuum itself.…”