Femtosecond Infrared Spectroscopic Studies of Protein Dynamics

Ultrafast methods of interrogating the molecular vibrational spectrum in the infrared have advanced significantly in the past few years (1). Experiments in the regime 1200 cm–1 to 3500 cm–1 are now demonstrated and IR pulses as short as 280 fs have been used in experiments near 5 µ. Because infrared spectroscopy is universally applicable and structurally sharp, it is a particularly powerful tool with which to investigate complex systems such as proteins. In this paper some recent results in which transient IR spectroscopy was used to explore changes in the vibrational spectrum that result from optical triggering of protein structural changes will be discussed.