Single-molecule spectroscopy of pigment protein complexes

• Applicant: Privatdozent Dr. Marc Brecht
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 178670544

Single-molecule spectroscopy of protein bound chromophores at low temperatures can provide detailed information about the conformational state and the conformational dynamics of proteins. The significance of this method is limited by the low optical quality of microscope objectives for low-temperature applications, the intrinsic weak signals of single emitters, and the huge amount of cryoprotectants that must be added to protein samples. Over the past several years research has shown that more efficient detection is possible by using reflective optical elements like highprecision parabolic mirrors, or by placing the proteins close to metal nanoparticles.Furthermore, the addition of cryoprotectants can be omitted if the samples are vitrified using quick-freezing, e.g. plunging in liquid ethane or high-pressure freezing, standard methods used in electron microscopy. This project combines the advantages of single-molecule detection using parabolic mirrors, metal nanoparticles and high-pressure freezing. Pigment proteins will be studied in states close to their native state using the advantages of the low-temperature approach. Moreover, the determination of the influence of different standard preparation methods, like the addition of glass formers or fixation in polymer-matrices, is also possible. Close cooperation with the working group of Prof. Meixner at the University of Tübingen is essential for this project due to their leading experience with reflective optics and the synthesis/application of various metal nanoparticles and nanostructures.

• DFG Programme: Research Grants
• Major Instrumentation: Komponenten für ein Probentransfersystem incl. optischen TCSPC-Aufbau
• Instrumentation Group: 5360 Meßgeräte für gestreutes und reflektiertes Licht, optische Oberflächen-Prüfgeräte