Time-resolved circular dichroism: Application to the study of conformal changes in biomolecules

F Hache

doi:10.1051/epjconf/20100503003

Abstract

Circular dichroism (CD) is known to be a very sensitive probe of the conformation of molecules and biomolecules. It is therefore tempting to implement CD in a pump-probe experiment in order to measure ultrarapid conformational changes which occur in photochemical processes. We present two technical developments of such time-resolved CD experiments. The first one relies on the modulation of the probe polarization from left to right circular whereas the second one measures the pump-induced ellipticity of the probe with a Babinet-Soleil compensator. Some applications are described and extension of these techniques towards the study of elementary protein folding processes is discussed.

Highlights

Circular dichroism (CD), the difference in absorption for a left or a right circularly polarized light, is with optical rotation a unique optical characteristics of chiral molecules
Because chirality is primarily a geometrical property, CD is in turn very sensitive to the conformation of molecules
Taking advantage of our knowledge in ultrafast optics and nonlinear optical properties of chiral molecules, we have developed new experimental schemes allowing such time-resolved CD (TRCD) measurements

Summary

Introduction

Circular dichroism (CD), the difference in absorption for a left or a right circularly polarized light, is with optical rotation a unique optical characteristics of chiral molecules. Because chirality is primarily a geometrical property, CD is in turn very sensitive to the conformation of molecules. This feature makes CD an attractive probe for stereochemistry and especially for the study of biomolecules [1]. Taking advantage of our knowledge in ultrafast optics and nonlinear optical properties of chiral molecules, we have developed new experimental schemes allowing such time-resolved CD (TRCD) measurements

Time-resolved CD

Modulation of the probe polarization

Measurement of the pump-induced change in the probe ellipticity

Conclusion and perspectives