title: Dissociation of nitric oxide from soluble guanylate cyclase.
abstract: Kinetic studies of soluble guanylate cyclase complexed with nitric oxide prove that NO dissociation in the presence of the substrate GTP and Mg2+ is as much as 50 times faster than in their absence. In the presence of those two reagents the dissociation rate constant is k(obs) = 0.04 +/- 0.01 s-1 at 20 degrees C, which is by far the fastest NO dissociation rate constant ever reported for a ferrous heme protein. Extrapolated to 37 degrees C, this corresponds to a half life of about 5 s for NO dissociation from soluble guanylate cyclase at physiological conditions, which is presumably fast enough to account for deactivation of the enzyme in biological systems. Dissociation rate constants are also reported for a variety of other reagent conditions.
authors.affiliation: Department of Chemistry, University of California at San Diego, La Jolla 92093-0652, USA.
authors.forename: V G
authors.initials: VG
authors.lastname: Kharitonov
authors.forename: M
authors.initials: M
authors.lastname: Russwurm
authors.forename: D
authors.initials: D
authors.lastname: Magde
authors.forename: V S
authors.initials: VS
authors.lastname: Sharma
authors.forename: D
authors.initials: D
authors.lastname: Koesling
mesh_terms: D000818:Animals; D002417:Cattle; D006160:Guanosine Triphosphate / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism*; D007700:Kinetics; D008168:Lung / Q000201:enzymology; D008274:Magnesium / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D012995:Solubility
chemical_list: D009569:Nitric Oxide; D006160:Guanosine Triphosphate; D006162:Guanylate Cyclase; D008274:Magnesium