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BP: Fachverband Biologische Physik

BP 22: Molecular Machines

BP 22.11: Vortrag

Donnerstag, 29. März 2007, 12:45–13:00, H43

Data Analysis with Hidden Markov Models on a single rotary motor FoF1-ATP synthase — •Nawid Zarrabi, Monika Düser, and Michael Börsch — 3. Physikalisches Institut, Pfaffenwaldring 57, Universität Stuttgart, 70569 Stuttgart

The formation of ATP from ADP and phosphate is the major reaction that provides the 'chemical energy' for living organisms. This reaction is performed by a stepwise internal rotation of subunits of the enzyme FoF1-ATP synthase. We modeled the stepwise subunit rotation of the ATP synthase with Hidden Markov Models (HMM) and evaluated those models with confocal single-molecule fluorescence resonance energy transfer (FRET) data [1,2]. To monitor the capability of the HMM approach we generated single molecule data of freely diffusing enzymes in liposoms by a Monte-Carlo-simulation. Thereby we included the intensity fluctuations due to Brownian motion. The rotary catalysis of the ATP synthase was described by a Markov process with predefined rates for forward and backward steps. The aim of the data analysis method was the determination of dynamic parameters of ATP synthase, i.e. the occurrence of substeps depending on the ATP concentration.

References: [1] B. Zimmermann, N. Zarrabi, M. Diez, P. Gräber, M. Börsch, (2005) EMBO J. 24:2053-2063. [2] M. G. Düser, N. Zarrabi, Y. Bi, B. Zimmermann, S. D. Dunn, M. Börsch (2006) Proc. of SPIE 6062:89-104.