Joint CCS/PChem Seminar Features Paul Champion, “Vibrationally Enhanced Deep Proton Tunneling in Protons”

The Boston University Center for Computational Science and Physical Chemistry will be hosting a special joint seminar featuring Professor Paul Champion, Physics Department Chair at Northeastern University.

Vibrationally Enhanced Deep Proton Tunneling in Proteins

2:00 PM on February 20, 2015

Physics Research Building, 3 Cummington Mall, Room 595

Abstract: 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.