Electron paramagnetic resonance- (EPR-) resolved kinetics of cryogenic nitric oxide recombination to cytochrome c oxidase and myoglobin

Journal Article · Wed Feb 01 04:00:00 EST 1984 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(84)84171-5· OSTI ID:6834934

LoBrutto, R; Wei, Y H; Yoshida, S; Van Camp, H L; Scholes, C P; King, T E

By the electron paramagnetic resonance (EPR) technique, recovery kinetics for nitric oxide (NO) to heme following cryogenic photolysis were studied for the nitrosylferrocytochrome a/sub 3/ center in cytochrome c oxidase and for myoglobin. The recovery was nonexponential, as has been observed in previous cryogenic CO and O/sub 2/ rebinding to heme systems. NO rebinding to heme a/sub 3/ started near a temperature of 50 K and was related to a distribution of thermal activation energies. At the peak of the distribution the activation energy was 3.1 kcal/mol, and the preexponential in the recovery rate was 10/sup 9.9/s/sup -1/. For recovery of NO back to the a/sub 3/ heme, the activation energy was threefold less than that for CO where CO binds to nearby Cu/sub a3/ following photolysis from heme a/sub 3/, but was larger than the activation energy for CO, O/sub 2/, and probably NO rebinding to myoglobin. NO ligand rebinding to myoglobin occurred at a temperature as low as 15 K and in a temperature regime where tunneling could occur. However, the rate of NO rebinding to myoglobin did increase with temperature in the 15-25 K range.

• Research Organization: State Univ. of New York, Albany
• OSTI ID: 6834934
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 45:2; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ACTIVATION ENERGY
BIOCHEMICAL REACTION KINETICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
COPPER
CRYOGENICS
CYTOCHROME OXIDASE
DECOMPOSITION
ELECTRON SPIN RESONANCE
ELEMENTS
ENERGY
ENZYMES
GLOBIN
HAEM DEHYDROGENASES
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
MAGNETIC RESONANCE
METALS
MYOGLOBIN
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PIGMENTS
PORPHYRINS
PROTEINS
REACTION KINETICS
RESONANCE
TRANSITION ELEMENTS
VERY LOW TEMPERATURE