University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Colloquium

Wednesday, February 18th 2009
3:35 pm:
Speaker: David Thomas, University of Minnesota
Subject: Structural dynamics of muscle proteins resolved simultaneously on nanosecond and millisecond time scales

We have constructed an instrument that records a complete time-domain laser fluorescence decay, resolved on the subnanosecond time scale, 10000 times per second, with high S/N and reproducibility. We are using this instrument to measure intramolecular and intermolecular distances in muscle proteins during their biochemical activities. This is accomplished by time-resolved fluorescence resonance energy transfer (TR-FRET), which can determine complex distance interprobe distributions in the range from 2 to 8 nm. When this experiment is performed following the rapid mixing of proteins and substrates, we record these signals resolved on the millisecond time scale of biochemical kinetics. This new experiment, called transient time-resolved FRET, (TR)2FRET, provides multidimensional structural information on the time scale of biochemical reactions. We have used it to define the internal structural dynamics of two muscle proteins during their ATP-driven energy transduction processes: myosin, which generates force in contraction, and the calcium pump, which relaxes muscle by removing calcium after a contraction. These studies are being used to determine how the molecular machine works, how it fails in disease, and how to repair it therapeutically.

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