Humboldt-Universität zu Berlin - Experimentelle Biophysik

Dr. Eglof Ritter

Infrared (IR) spectroscopy is an important tool to study the structure and function of proteins. It allows to study these systems in their native environment and under natural operating conditions. However, to obtain information about a proteins function, time-resolved studies are mandatory. The state-of-the-art Fourier-Transform (FT) IR spectroscopy is however limited; it can only be used down to the Millisecond time regieme. A better time-resolution can only be achieved with FT-IR, when the systems to be investigated are cyclic and exactly the same reaction can be triggered thousandfold and in quick succession. However, many protein systems do not fulfil this requirement, for example channelrhodopsin which has a very slow cycling time, or visual rhodopsin, which after activations goes into an irreversible reaction cascade. For such samples, time-resolved “Single-Shot” measurements are needed. The aim of this project is the set-up of a novel end-station at the IRIS-beamline of BESSY II for simultaneous, microsecond time-resolved infrared (IR)- and UV/ Vis spectroscopy of non-cyclic or slow-cycling systems. The setup uses the unique properties of synchrotron radiation in combination with modern focal-plane array detectors to achieve a so far unreached performance for Single-Shot measurements on the sub-ms timescale.

Publications related to the project:

Marcelli A, Innocenzi P, Malfatti L, Newton MA, Rau J V., Ritter E, et al. IR and X-ray time-resolved simultaneous experiments: an opportunity to investigate the dynamics of complex systems and non-equilibrium phenomena using third-generation synchrotron radiation sources. J Synchrotron Radiat. 2012 Nov 1;19(6):892–904.

Ritter E, Piwowarski P, Hegemann P, Bartl FJ. Light-dark adaptation of channelrhodopsin C128T mutant. J Biol Chem. 2013;288(15):10451–8.

Schade U, Ritter E, Hegemann P, Aziz EF, Hofmann KP. Concept for a single-shot mid-infrared spectrometer using synchrotron radiation. Vib Spectrosc. Elsevier B.V.; 2014;75:190–5.

Ritter E, Puskar L, Bartl FJ, Aziz EF, Hegemann P, Schade U. Time-resolved infrared spectroscopic techniques as applied to channelrhodopsin. Front Mol Biosci. 2015;2(July):38.