A model of the copper centres of nitrous oxide reductase (Pseudomonas stutzeri)

FEBS Letters

Dooley, David M.¹  Farrar, Jaqui A.²  Cheesman, Myles R.²  Thomson, Andrew J.²  Zumft, Walter G.³ 

[1] Department of Chemistry, Amherst College, Amherst, MA 01002, USA;Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, NR4 7TJ, UK;Lehrstuhl für Mikrobiologie, Universität Karlsruhe, D-7500 Karlsruhe 1, Germany

关键词: Copper protein;    EPR;    MCD;    Nitrous oxide reductase;   

DOI  :  10.1016/0014-5793(91)81331-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Nitrous oxide reductase (N₂OR), Pseudomonas stutzeri, catalyses the 2 electron reduction of nitrous oxide to di-nitrogen. The enzyme has 2 identical subunits (M ₁ ∼ 70 000) of known amino acid sequence and contains ∼ 4 Cu ions per subunit. By measurement of the optical absorption, electron paramagnetic resonance (EPR) and low-temperature magnetic circular dichroism (MCD) spectra of the oxidised state, a semi-reduced form and the fully reduced state of the enzyme it is shown that the enzyme contains 2 distinct copper centres of which one is assigned to an electron-transfer function, centre A, and the other to a catalytic site, centre Z. The latter is a binuclear copper centre with at least 1 cysteine ligand and cycles between oxidation levels Cu(II)/Cu(II) and Cu(II)/Cu(I) in the absence of substrate or inhibitors. The state Cu(II)/Cu(I) is enzymatically inactive. The MCD spectra provide evidence for a second form of centre Z, which may be enzymatically active, in the oxidised state of the enzyme. Centre A is structurally similar to that of Cu_A in bovine and bacterial cytochrome c oxidase and also contains copper ligated by cysteine. This centre may also be a binuclear copper complex.

【 授权许可】

Unknown