Proton transport in bioenergetic proteins

The primary purpose of the proton transfer in living organisms is to translocate protons into and across the membrane, e.g., of the mitochondrion or cells to help generate proton gradient. The transfer of protons can include 1) highly localized acid-base catalysis that occurs generally pair wise between adjacent groups (e.g. an amino acid and a substrate) in the active site and 2) long distance proton transport that is typical in bioenergetics and is usually coupled to electron transfer or conformational changes induced by light or hydrolysis of ATP. The transport necessarily involves many elementary proton transfer steps constituting proton delivery pathway in permanent or transiently formed structure of the protein where proton donors and acceptors line up and form bucket-brigade mechanism to transport H+ ions. There are not only energetic constraints (e.g. pathway should be formed) but also kinetic limitations, because usually high rate of proton delivery is needed to reduce the dissipation (losses) of the available free energy by competing additional processes. In this lecture, the transfer of protons in some selected channels and bioenergetic proteins will be introduced to demonstrate the design of functionality of long distance proton transport of biological interest. As a model system, the proton-activated second electron transfer in reaction center protein of photosynthetic bacteria will be set into the focus of the talk.
 

All Faculty, staff and students are invited
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SP-367-11 at 2:30 PM
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