1w5u: Difference between revisions

Gramicidin D (gD) is a naturally occurring ionophoric antibiotic that, forms membrane channels specific for monovalent cations. The crystal, structure of the RbCl complex of gD has been determined at 1.14 A, resolution from low-temperature (100 K) synchrotron-radiation data with a, final R of 16%. The structure was refined with anisotropic temperature, factors for all non-H atoms and with partial occupancies for many of them., The asymmetric unit in the crystal contains four crystallographically, independent molecules that form two right-handed antiparallel, double-stranded dimers. There are seven distinct rubidium-binding sites in, each dimeric channel. The occupancy factors of Rb cations are between 0.11, and 0.35 and the total ion contents of the two crystallographically, independent channels are 1.59 and 1.22 ions, respectively. Although each, channel is 'chemically symmetrical', the side-chain conformations, the, distributions of rubidium cations and their binding sites in the two, independent channels are not. Cations are 'coordinated' by delocalized, pi-electrons of three to five carbonyl groups that together with peptide, backbone chains form the gramicidin channel walls. The water:cation ratio, in the channel interior is four or five:one, and five or six waters, separate Rb cations during their passage through the channel.

1W5U is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Brevibacillus_brevis Brevibacillus brevis] with RB, CL, FOR and EOH as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Site: AC9. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1W5U OCA].  

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov  5 13:29:52 2007''