1e2r
CYTOCHROME CD1 NITRITE REDUCTASE, REDUCED AND CYANIDE BOUND
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedWe 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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