1e0p: Difference between revisions

A wide variety of mechanisms are used to generate a proton-motive, potential across cell membranes, a function lying at the heart of, bioenergetics. Bacteriorhodopsin, the simplest known proton pump, provides, a paradigm for understanding this process. Here we report, at 2.1 A, resolution, the structural changes in bacteriorhodopsin immediately, preceding the primary proton transfer event in its photocycle. The early, structural rearrangements propagate from the protein's core towards the, extracellular surface, disrupting the network of hydrogen-bonded water, molecules that stabilizes helix C in the ground state. Concomitantly, a, bend of this helix enables the negatively charged primary proton acceptor, Asp 85, to approach closer to the positively charged primary proton donor, the Schiff base. The primary proton transfer event would then neutralize, these two groups, cancelling their electrostatic attraction and, facilitating a relaxation of helix C to a less strained geometry., Reprotonation of the Schiff base by Asp 85 would thereby be impeded, ensuring vectorial proton transport. Structural rearrangements also occur, near the protein's surface, aiding proton release to the extracellular, medium.

1E0P is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Halobacterium_salinarum Halobacterium salinarum] with RET as [http://en.wikipedia.org/wiki/ligand ligand]. Structure known Active Sites: AC1 and AC2. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1E0P OCA].  

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov  5 14:53:47 2007''