title: Electron paramagnetic resonance spectral evidence for the formation of a pentacoordinate nitrosyl-heme complex on soluble guanylate cyclase.
abstract: Nitric oxide (.NO) is an important intercellular signaling agent throughout the animal kingdom. The majority of the effects of .NO is due to the direct stimulation of soluble guanylate cyclase (sGC). It has been proposed that .NO activates sGC by interacting with a heme moiety on the enzyme. The electron paramagnetic resonance (EPR) spectra of the ferrous-[14N/15N]nitrosyl complexes of the purified enzyme have been obtained. The spectrum of the [14N]nitrosyl-sGC complex was almost identical to that of a 5-coordinate. Hyperfine coupling constants and g-values were determined from computer simulations of the EPR spectra. Electronic absorption spectroscopy was used to show that the 5-coordinate nitrosyl complex on sGC forms under conditions that are typically used to assay activation of the enzyme.
authors.affiliation: Department of Biological Chemistry, School of Medicine, University of Michigan, Ann Arbor 48109-1065.
authors.forename: J R
authors.initials: JR
authors.lastname: Stone
authors.forename: R H
authors.initials: RH
authors.lastname: Sands
authors.forename: W R
authors.initials: WR
authors.lastname: Dunham
authors.forename: M A
authors.initials: MA
authors.lastname: Marletta
mesh_terms: D003198:Computer Simulation; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000378:metabolism; D006418:Heme / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D009569:Nitric Oxide / Q000378:metabolism
chemical_list: D009569:Nitric Oxide; D006418:Heme; C027417:nitrosylprotoheme; D006162:Guanylate Cyclase