Physics Colloquium
Monday, February 7th, 2005, 4:00 P.M.

Jennifer Ogilvie

Ecole Polytechnique

Watching Proteins in Action – A Laser Spectroscopist’s View of Protein Function

As many as 100,000 different proteins execute and control essentially all functions within living organisms. These proteins are the product of billions of years of evolution, and nature has optimized them to perform their functions in reliable and efficient ways. The oxygen storage protein, myoglobin, represents one of the most thoroughly characterized proteins, making it the “hydrogen atom” of structural biology. Studying the X-ray structure of this protein reveals a fascinating puzzle: although oxygen entry and exit is essential to myoglobin’sfunction, there is no apparent pathway through which this can occur. The answer to this puzzle cannot be found from a static description of protein structure: dynamical pathways open and close to shuttle oxygen to and from the storage site. Clearly dynamics are inextricably linked to structure, and obtaining a physical description of protein function requires that we watch proteins in action. The diverse techniques of laser spectroscopy allow us to do this; providing snapshots from femtosecondbond-breaking events that initiate protein function, to large scale structure changes and diffusion processes that last microseconds to milliseconds. Spectroscopic studies covering the full range of time scales of myoglobinfunction will illustrate what several laser spectroscopic techniques can teach us about protein function.