1e2r
|
CYTOCHROME CD1 NITRITE REDUCTASE, REDUCED AND CYANIDE BOUND
OverviewOverview
We present a 1.59-A resolution crystal structure of reduced Paracoccus, pantotrophus cytochrome cd(1) with cyanide bound to the d(1) heme and, His/Met coordination of the c heme. Fe-C-N bond angles are 146 degrees for, the A subunit and 164 degrees for the B subunit of the dimer. The nitrogen, atom of bound cyanide is within hydrogen bonding distance of His(345) and, His(388) and either a water molecule in subunit A or Tyr(25) in subunit B., The ferrous heme-cyanide complex is unusually stable (K(d) approximately, 10(-6) m); we propose that this reflects both the design of the, specialized d(1) heme ring and a general feature of anion reductases with, active site heme. Oxidation of crystals of reduced, cyanide-bound, cytochrome cd(1) results in loss of cyanide and return to the native, structure with Tyr(25) as a ligand to the d(1) heme iron and switching to, His/His coordination at the c-type heme. No reason for unusually weak, binding of cyanide to the ferric state can be identified; rather it is, argued that the protein is designed such that a chelate-based effect, drives displacement by tyrosine of cyanide or a weaker ligand, like, reaction product nitric oxide, from the ferric d(1) heme.
About this StructureAbout this Structure
1E2R is a Single protein structure of sequence from Paracoccus denitrificans with CYN, HEC, DHE and GOL as ligands. Full crystallographic information is available from OCA.
ReferenceReference
X-ray crystallographic study of cyanide binding provides insights into the structure-function relationship for cytochrome cd1 nitrite reductase from Paracoccus pantotrophus., Jafferji A, Allen JW, Ferguson SJ, Fulop V, J Biol Chem. 2000 Aug 18;275(33):25089-94. PMID:10827177
Page seeded by OCA on Tue Nov 20 13:45:08 2007