Dec 11, 1975

The reaction between the superoxide anion radical and cytochrome c

Biochimica Et Biophysica Acta
J ButlerA J Swallow

Abstract

1. The superoxide anion radical (O2-) reacts with ferricytochrome c to form ferrocytochrome c. No intermediate complexes are observable. No reaction could be detected between O2- and ferrocytochrome c. 2. At 20 degrees C the rate constant for the reaction at pH 4.7 to 6.7 is 1.4-10(6) M-1. S -1 and as the pH increases above 6.7 the rate constant steadily decreases. The dependence on pH is the same for tuna heart and horse heart cytochrome c. No reaction could be demonstrated between O2- and the form of cytochrome c which exists above pH approximately 9.2. The dependence of the rate constant on pH can be explained if cytochrome c has pKs of 7.45 and 9.2, and O2- reacts with the form present below pH 7.45 with k = 1.4-10(6) M-1 - S-1, the form above pH 7.45 with k = 3.0- 10(5) M-1 - S-1, and the form present above pH 9.2 with k = 0. 3. The reaction has an activation energy of 20 kJ mol-1 and an enthalpy of activation at 25 degrees C of 18 kJ mol-1 both above and below pH 7.45. It is suggested that O2- may reduce cytochrome c through a track composed of aromatic amino acids, and that little protein rearrangement is required for the formation of the activated complex. 4. No reduction of ferricytochrome c by HO2 radicals could be de...Continue Reading

  • References3
  • Citations33

Citations

Mentioned in this Paper

CYCS
Thermodynamics
Dioxygen
Amino Acids, I.V. solution additive
Complex (molecular entity)
Free Radicals
Tuna (fish)
Myocardium
Radicals (chemistry)
Superoxides

About this Paper

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

Head And Neck Squamous Cell Carcinoma

Squamous cell carcinomas account for >90% of all tumors in the head and neck region. Head and neck squamous cell carcinoma incidence has increased dramatically recently with little improvement in patient outcomes. Here is the latest research on this aggressive malignancy.

Signaling in Adult Neurogenesis

Neural stem cells play a critical role in the production of neuronal cells in neurogenesis is of great importance. Of interest is the role signalling mechanisms in adult neurogenesis. Discover the latest research on signalling in adult neurogenesis.

Psychiatric Chronotherapy

Psychiatric Chronotherapy considers the circadian rhythm as a major factor for optimizing therapeutic efficacy of psychiatric interventions. Discover the latest research on Psychiatric Chronotherapy here.

Bone Marrow Neoplasms

Bone Marrow Neoplasms are cancers that occur in the bone marrow. Discover the latest research on Bone Marrow Neoplasms here.

IGA Glomerulonephritis

IgA glomerulonephritis is a chronic form of glomerulonephritis characterized by deposits of predominantly Iimmunoglobin A in the mesangial area. Discover the latest research on IgA glomerulonephritis here.

Cryogenic Electron Microscopy

Cryogenic electron microscopy (Cryo-EM) allows the determination of biological macromolecules and their assemblies at a near-atomic resolution. Here is the latest research.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.