PDBsum entry 2o5t

Oxygen storage/transport

PDB id: 2o5t

Contents

Protein chain

152 a.a. *

Ligands

SO4 ×2

COH

Waters ×147

* Residue conservation analysis

PDB id:

2o5t

Name:

Oxygen storage/transport

Title:

Cobalt horse heart myoglobin, oxidized

Structure:

Myoglobin. Chain: x

Source:

Equus caballus. Horse. Organism_taxid: 9796. Organ: heart

Resolution:

1.60Å R-factor: 0.195 R-free: 0.248

Authors:

G.B.Richter-Addo,Z.N.Zahran,L.Chooback,D.M.Copeland,A.H.West

Key ref:

Z.N.Zahran et al. (2008). Crystal structures of manganese- and cobalt-substituted myoglobin in complex with NO and nitrite reveal unusual ligand conformations. J Inorg Biochem, 102, 216-233. PubMed id: 17905436

Date:

06-Dec-06 Release date: 16-Oct-07

Protein chain

P68082  (MYG_HORSE) -  Myoglobin from Equus caballus

Seq: 154 a.a.

Struc: 152 a.a.

J Inorg Biochem 102:216-233 (2008)

PubMed id: 17905436

Crystal structures of manganese- and cobalt-substituted myoglobin in complex with NO and nitrite reveal unusual ligand conformations.

Z.N.Zahran, L.Chooback, D.M.Copeland, A.H.West, G.B.Richter-Addo.

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.