2O5T

Cobalt horse heart myoglobin, oxidized

Summary for 2O5T

• Entry DOI: 10.2210/pdb2o5t/pdb
• Related: 1MMB 2O58 2O5B 2O5L 2O5M 2O5O 2O5Q 2O5S
• Descriptor: Myoglobin, SULFATE ION, PROTOPORPHYRIN IX CONTAINING CO, ... (4 entities in total)
• Functional Keywords: cobalt protoporphyrin ix, cobalt myoglobin, oxidized form, horse heart, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Equus caballus (horse)
• Total number of polymer chains: 1
• Total formula weight: 17795.22

Authors

Richter-Addo, G.B.,Zahran, Z.N.,Chooback, L.,Copeland, D.M.,West, A.H. (deposition date: 2006-12-06, release date: 2007-10-16, Last modification date: 2023-12-27)

Primary citation

Zahran, Z.N.,Chooback, L.,Copeland, D.M.,West, A.H.,Richter-Addo, G.B.
Crystal structures of manganese- and cobalt-substituted myoglobin in complex with NO and nitrite reveal unusual ligand conformations.
J.Inorg.Biochem., 102:216-233, 2008

PubMed Abstract: 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.

PubMed: 17905436
DOI: 10.1016/j.jinorgbio.2007.08.002

Experimental method

X-RAY DIFFRACTION (1.6 Å)