1brx
From Proteopedia
|
BACTERIORHODOPSIN/LIPID COMPLEX
Overview
Photoisomerization of the retinal of bacteriorhodopsin initiates a cyclic, reaction in which a proton is translocated across the membrane. Studies of, this protein promise a better understanding of how ion pumps function., Together with a large amount of spectroscopic and mutational data, the, atomic structure of bacteriorhodopsin, determined in the last decade at, increasing resolutions, has suggested plausible but often contradictory, mechanisms. X-ray diffraction of bacteriorhodopsin crystals grown in cubic, lipid phase revealed unexpected two-fold symmetries that indicate, merohedral twinning along the crystallographic c axis. The structure, refined to 2.3 angstroms taking this twinning into account, is different, from earlier models, including that most recently reported. One of the, carboxyl oxygen atoms of the proton acceptor Asp85 is connected to the, proton donor, the retinal Schiff base, through a hydrogen-bonded water and, forms a second hydrogen bond with another water. The other carboxyl oxygen, atom of Asp85 accepts a hydrogen bond from Thr89. This structure forms the, active site. The nearby Arg82 is the center of a network of numerous, hydrogen-bonded residues and an ordered water molecule. This network, defines the pathway of the proton from the buried Schiff base to the, extracellular surface.
About this Structure
1BRX is a Single protein structure of sequence from Halobacterium salinarum with RET as ligand. Full crystallographic information is available from OCA.
Reference
Proton transfer pathways in bacteriorhodopsin at 2.3 angstrom resolution., Luecke H, Richter HT, Lanyi JK, Science. 1998 Jun 19;280(5371):1934-7. PMID:9632391
Page seeded by OCA on Tue Nov 20 11:52:10 2007
