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Special Joint CCS/PChem Seminar
Friday - February 20, 2015
2:00 PM
Physics Research Building - Room 595
3 Cummington Mall

Professor Paul Champion
Physics Department Chair
Northeastern University

"Vibrationally Enhanced Deep Proton Tunneling in Proteins"

Ground electronic state proton tunneling kinetics have been measured over an unprecedented dynamic range of time and temperature using a light-triggered “proton wire” in green fluorescent protein. The data reveal a large temperature-dependent kinetic isotope effect and demonstrate sub-nanosecond vibrationally enhanced “deep tunneling” at room temperature for a typical hydrogen bonded donor-acceptor (D-A) oxygen equilibrium distance of ~2.7-2.8Å. A two-dimensional quantum oscillator model, which includes normal modes composed of the D-A and hydrogen atom stretching motions, predicts the temperature and isotope dependence of the observed rates on an absolute scale using only three free parameters: the equilibrium tunnel distance (0.78Å), a Marcus reorganization energy (1175cm-1), and the D-A stretching frequency (271 cm-1). We conclude that room temperature deep tunneling is likely to dominate proton transfer through typical H-bonded networks in proteins





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