Equilibrium and kinetic evidence for a transition between six- and five-coordinate ferrous heme in the nitric oxide derivative of Aplysia myoglobin
| Autor: | Eraldo Antonini, Maurizio Brunori, G. Rotilio, Paolo Ascenzi, Gm Giacometti |
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| Přispěvatelé: | Ascenzi, Paolo, Giacometti, Gm, Antonini, E, Rotilio, G, Brunori, M. |
| Rok vydání: | 1981 |
| Předmět: |
Hemeprotein
Inorganic chemistry Heme Nitric Oxide Biochemistry Ferrous law.invention Adduct chemistry.chemical_compound law Aplysia Animals Electron paramagnetic resonance Molecular Biology Conformational isomerism Hyperfine structure Myoglobin Electron Spin Resonance Spectroscopy Cell Biology Hydrogen-Ion Concentration Crystallography Kinetics chemistry Spectrophotometry Spin Labels |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0021-9258 |
| Popis: | The pH dependence in the range 3--7 of the optical absorption and electron paramagnetic resonance of the nitric oxide adduct of ferrous Aplysia myoglobin is reported. Optical spectra in the Soret region show a transition between two conformers with an apparent pK in the range 3.5--5 depending on the presence of carboxylic anions as third component. In the same pH range, the EPR spectrum undergoes a change from a 9-line to a 3-line hyperfine pattern in the g. region, similar to that reported for synthetic heme derivatives and for other hemoproteins. The structural interpretation of the pH-induced transition experienced by Aplysia myoglobin nitric oxide is that of a proton-linked cleavage of the proximal bond as suggested by several lines of evidence. Temperature-jump measurements allowed an estimation of the relaxation time for the process, which is of the order of 0.3 ms at 25 degrees C. |
| Databáze: | OpenAIRE |
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