Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 26: From Single-Molecule to Tissue Dynamics

BP 26.3: Talk

Thursday, March 25, 2010, 14:45–15:00, H43

Monitoring a single F_oF₁-ATP synthase in an anti-Brownian electrokinetic (ABEL) trap — •Karin Seyfert, Torsten Rendler, Andrea Zappe, Stefan Ernst, Nawid Zarrabi, and Michael Börsch — 3. Physikalisches Institut, Pfaffenwaldring 57, 70569 Stuttgart

ATP (adenosine triphosphate) is the energy currency of every cell. It is produced by the F_oF₁-ATP synthase. This membrane-embedded enzyme consists of two rotary motors. To analyze the functioning of this enzyme, we measure FRET (Fluorescence Resonance Energy Transer) with single, freely diffusing F_oF₁-ATP synthases in a confocal microscope. The disadvantage of this method is the limited observation time up to 300 ms due to Brownian motion [1]. We aim to trap the enzyme inside the confocal volume. The ABEL (Anti Brownian Electrokinetic) trap is a microfluidic system invented by A.E. Cohen (Harvard) and W.E. Moerner (Stanford) [2]. Fluorescent lipid vesicles containing a single FRET-labeled ATP synthase are monitored by an EMCCD camera and the image is used for the electrokinetic feedback in real time to bring the vesicle back to a set point. Thereby, extended FRET measurements on a single enzyme in solution are possible.

[1] M.G. Duser, N. Zarrabi, D.J. Cipriano, S. Ernst, G.D. Glick, S.D. Dunn, and M. Borsch: 36 degrees step size of proton-driven c-ring rotation in FoF1-ATP synthase, Embo Journal 28, 2689 (2009). [2] A.E. Cohen and W.E. Moerner: Suppressing Brownian motion of individual biomolecules in solution, Proc Natl Acad Sci U S A 103, 4362 (2006).