Stoichiometry, ATP/2e values, and energy requirements for reactions catalyzed by nitrogenase from Azotobacter vinelandii
| Autor: | Hadfield Kl, William A. Bulen, Gerald D. Watt, Burns A |
|---|---|
| Rok vydání: | 1975 |
| Předmět: |
Ethylene
Manometry Inorganic chemistry Calorimetry Biochemistry Redox Catalysis chemistry.chemical_compound Adenosine Triphosphate Nitrogenase biology Acetylene Dithionite biology.organism_classification Enzyme structure Energy Transfer chemistry Azotobacter vinelandii Azotobacter Thermodynamics Sulfonic Acids Oxidation-Reduction Stoichiometry Hydrogen Polarography |
| Zdroj: | Biochemistry. 14:4266-4272 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi00690a019 |
| Popis: | The stoichiometry of the nitrogenase ATP-dependent H2 evolution and ecetylene reduction reactions using S2O4(2-) as an electron source was studied by various techniques. For each mole of S2O4(2-) oxidized to 2SO3(2-) by the enzyme-catalyzed reactions at 25 degrees and pH 8, 1 mol of H2 (1 mol of ethylene for acetylene reduction) and two protons are produced. Under these conditions, 4.5 mol of ATP was hydrolyzed to ADP and inorganic phosphate for each S2O4(2-) oxidized. ATP/S2O4(2-) (ATP/2e) values determined at 5 degree intervals from 10 to 35 degrees were found to go through a minimum at 20 degrees. This effect is explained in terms of possible enzyme structure modifications. Calorimetric measurements for the enzyme-catalyzed H2 evolution and acetylene reduction reactions gave deltaH values of -32.4 and -75.1 kcal/mol of S2O4(2-), respectively. |
| Databáze: | OpenAIRE |
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