5mba: Difference between revisions

[[Image:5mba.gif|left|200px]]<br /><applet load="5mba" size="350" color="white" frame="true" align="right" spinBox="true"  

The binding mode of azide to the ferric form of Aplysia limacina myoglobin has been studied by X-ray crystallography. The three-dimensional structure of the complex has been refined at 1.9 A resolution to a crystallographic R-factor of 13.9%, including 126 ordered solvent molecules. Azide binds to the heme iron, at the sixth co-ordination position, and is oriented towards the outer part of the distal site crevice. This orientation is stabilized by an ionic interaction with the side-chain of Arg66 (E10) which, from an outer orientation in the 'aquo-met' ligand-free myoglobin, folds back towards the distal site in the presence of the anionic ligand. In the absence of a hydrogen bond donor residue at the distal E7 position in Aplysia limacina myoglobin, a different polar residue, Arg66 at the E10 topological position, has been selected by molecular evolution in order to grant ligand stabilization.

5MBA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aplysia_limacina Aplysia limacina] with <scene name='pdbligand=AZI:'>AZI</scene>, <scene name='pdbligand=ACE:'>ACE</scene> and <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. This structure supersedes the now removed PDB entry 2MBA. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5MBA OCA].  

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