Levich Institute Seminar Announcement, 03/24/2015
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Marilyn Gunner
City College of CUNY
"Mechanism of Biological Proton Pumps "
A transmembrane proton gradient is established in cells by proton pumping through membrane embedded proteins from the high pH, N-side of the membrane to the low pH. The energy to build the gradient comes from sunlight in photosynthesis or from energy liberated by redox chemistry such as in the reduction of oxygen in cytochrome c oxidase. The proton gradient fuels the controlled transfer of ions and substrates across the membrane needed for cell signaling and metabolism and the production of ATP, the universal energy currency for biochemical reactions, by the F0/F1 ATPase. To pump protons the protein must change the proton affinity of buried amino acids and active site ligands that serve as intermediate proton donors and acceptors. A hydrogen bond pathway containing ionizable and polar residues and waters must exist to connect proton donors and acceptors. The accessibility of proton transfer pathways to the N- and P-sides of the membrane must also change during the reaction cycle to ensure that the proton transfers do not dissipate the proton gradient. The gates that change the conductivity of the proton transfer have been difficult to identify as they must be transient and may occur anywhere along the proton transfer pathways. I will discuss motifs we have identified by which proteins change the proton affinity and new methods to track the accessibility.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
CCNY physics professor from 1992; PhD U Penn biophysics then Post doc at columbia