2o5o: Difference between revisions

Revision as of 09:13, 13 February 2008

Manganese horse heart myoglobin, nitrite modified

OverviewOverview

Nitrite is now recognized as a storage pool of bioactive nitric oxide, (NO). Hemoglobin (Hb) and myoglobin (Mb) convert, under certain, conditions, nitrite to NO. This newly discovered nitrite reductase, activity of Hb and Mb provides an attractive alternative to mammalian NO, synthesis from the NO synthase pathway that requires dioxygen. We recently, reported the X-ray crystal structure of the nitrite adduct of ferric horse, heart Mb, and showed that the nitrite ligand binds in an unprecedented, O-binding (nitrito) mode to the d(5) ferric center in Mb(III)(ONO) [D.M., Copeland, A. Soares, A.H. West, G.B. Richter-Addo, J. Inorg. Biochem. 100, (2006) 1413-1425]. We also showed that the distal pocket in Mb allows for, different conformations of the NO ligand (120 degrees and 144 degrees ) in, Mb(II)NO depending on the mode of preparation of the compound. In this, article, we report the crystal structures of the nitrite and NO adducts of, manganese-substituted hh Mb (a d(4) system) and of the nitrite adduct of, cobalt-substituted hh Mb (a d(6) system). We show that the distal His64, residue directs the nitrite ligand towards the rare nitrito O-binding mode, in Mn(III)Mb and Co(III)Mb. We also report that the distal pocket residues, allow a stabilization of an unprecendented bent MnNO moiety in Mn(II)MbNO., These crystal structural data, when combined with the data for the aquo, methanol, and azide MnMb derivatives, provide information on the role of, distal pocket residues in the observed binding modes of nitrite and NO, ligands to wild-type and metal-substituted Mb.

About this StructureAbout this Structure

2O5O is a Single protein structure of sequence from Equus caballus with , and as ligands. Known structural/functional Sites: , , and . Full crystallographic information is available from OCA.

ReferenceReference

Crystal structures of manganese- and cobalt-substituted myoglobin in complex with NO and nitrite reveal unusual ligand conformations., Zahran ZN, Chooback L, Copeland DM, West AH, Richter-Addo GB, J Inorg Biochem. 2007 Aug 25;. PMID:17905436

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	[[Category: oxygen storage/transport complex]]		[[Category: oxygen storage/transport complex]]

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