X-ray structure of the NO-bound Cu_Bin bovine cytochromecoxidase

Abstract

The X-ray crystallographic structure of nitric oxide-treated bovine heart cytochrome c oxidase (CcO) in the fully reduced state has been determined at 50 K under light illumination. In this structure, nitric oxide (NO) is bound to the CcO oxygen-reduction site, which consists of haem and a Cu atom (the haem a(3)-Cu(B) site). Electron density for the NO molecule was observed close to Cu(B). The refined structure indicates that NO is bound to Cu(B) in a side-on manner.

Kinetic studies of the reactions of O2 and NO with reduced Thermus thermophilus ba3 and bovine aa3 using photolabile carriers

“…A recent crystal structure of the bovine aa 3 -CO shows that CO binds to ${\text{Cu}}_{\text{B}}^{+}$ in a side-on fashion after photolysis of CO from heme ${\text{italica}}_3^{2+}$. The ${\text{Cu}}_{\text{B}}^{+}$-to-carbon and ${\text{Cu}}_{\text{B}}^{+}$-to-oxygen atom distances of 2.4 and 2.7 Å, respectively, indicate a very weak ${\text{Cu}}_{\text{B}}^{+}$ – CO bond [44,45]. Significantly, no infrared linear dichroism was observed for the transient photoproduct of the CO-bound bovine aa 3 , which was interpreted in terms of CO being bound to ${\text{Cu}}_{\text{B}}^{+}$ at the “magic angle” to the heme normal [46]; another explanation is that the photodissociated CO does not bind to ${\text{Cu}}_{\text{B}}^{+}$.…”

Central pathology review in multicenter trials and studies

“…The biological Cu A site is a binuclear copper center in cytochrome c oxidase (C c O)1–14 and nitrous oxide reductase (N 2 OR) 15–18. It can perform rapid long‐range electron transfer from an electron source such as cytochrome c 2–5.…”

“…Many experimental and theoretical studies have revealed geometrical and electronic properties of the Cu A site 1–37. Three‐dimensional X‐ray crystallographic structures of the Cu A site from C c O, N 2 OR, and engineered blue copper proteins show the characteristic structural feature, as shown in Figure 1 6–14, 17–19. It is composed of two copper ions bridged by the thiolate groups of two conserved Cys residues, and each copper ion is coordinated equatorially with a His residue and axially with either a Met residue or a peptide carbonyl group.…”

Spectroscopic Elucidation of a New Heme/Copper Dioxygen Structure Type: Implications for O⋅⋅⋅O Bond Rupture in Cytochrome c Oxidase

“…If the spectral features of resting CcO are correctly interpreted, a more likely coordination mode for the peroxo to Cu is η 2 , [31] as in the recent crystallographic structure of a side-on nitrosyl bound to Cu B in CcO. [32] …”