A motif for reversible nitric oxide interactions in metalloenzymes.
Nitric oxide (NO) participates in numerous biological processes, such as signalling in the respiratory system and vasodilation in the cardiovascular system. Many metal-mediated processes involve direct reaction of NO to form a metal-nitrosyl (M-NO), as occurs at the Fe(2+) centres of soluble guanylate cyclase or cytochrome c oxidase. However, some copper electron-transfer proteins that bear a type 1 Cu site (His2Cu-Cys) reversibly bind NO by an unknown motif. Here, we use model complexes of type 1 Cu sites based on tris(pyrazolyl)borate copper thiolates [Cu(II)]-SR to unravel the factors involved in NO reactivity. Addition of NO provides the fully characterized S-nitrosothiol adduct [Cu(I)](κ(1)-N(O)SR), which reversibly loses NO on purging with an inert gas. Computational analysis outlines a low-barrier pathway for the capture and release of NO. These findings suggest a new motif for reversible binding of NO at bioinorganic metal centres that can interconvert NO and RSNO molecular signals at copper sites.
Department of Chemistry, Georgetown University, Box 571227, Washington, DC 20057, USA.
Shiyu
S
Zhang
Department of Chemistry, Georgetown University, Box 571227, Washington, DC 20057, USA.
Marie M
MM
Melzer
Department of Chemical Engineering, Yeditepe University, Istanbul 34755, Turkey.
S Nermin
SN
Sen
Department of Chemical Engineering, Yeditepe University, Istanbul 34755, Turkey.
Nihan
N
Çelebi-Ölçüm
Department of Chemistry, Georgetown University, Box 571227, Washington, DC 20057, USA.|Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, USA.
Timothy H
TH
Warren
D001881:Borates / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D008667:Metalloproteins / Q000737:chemistry* / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry* / Q000378:metabolism*; D011720:Pyrazoles / Q000737:chemistry
D001881:Borates; D008667:Metalloproteins; D011720:Pyrazoles; C555951:tris(pyrazolyl)borate; D009569:Nitric Oxide; D003300:Copper