| Autor: |
Vilhena FS; Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marquês de São Vicente, 225 Gávea, Rio de Janeiro, RJ CEP 22453.900, Brazil., Louro SR |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of inorganic biochemistry [J Inorg Biochem] 2004 Mar; Vol. 98 (3), pp. 459-68. |
| DOI: |
10.1016/j.jinorgbio.2003.12.011 |
| Abstrakt: |
The nitrosylation of two water-soluble iron-porphyrins, the anionic Fe(III)-meso-tetrakis(p-sulfonatophenyl)porphyrin (FeTPPS(4)) and the cationic Fe(III)-meso-tetrakis(4-N-methylpyridiniumyl)porphyrin (FeTMPyP), by the nitric oxide donor S-nitroso-N-acetylpenicillamine (SNAP) was studied using optical absorption spectroscopy. The influence of ionic and non-ionic micelles on rates of nitric oxide transfer was investigated. Initially, the effect of the micelles on the pH-dependent equilibrium between monomeric and micro-oxo-dimeric species of the iron-porphyrins was examined. It is not affected in micelle-porphyrin systems with electric charges identical in sign. The non-ionic micelles of polidocanol induce a small negative pK shift. In contrast, the dimerization equilibrium of porphyrins in oppositely charged micellar phases is displaced to lower pH by approximately 2 units. Nitric oxide binding to monomers and micro-oxo-dimers was examined at pH 5.0 and 8.0, respectively. Contrary to nitrosylation by NO gas, SNAP induces reductive nitrosylation. There was no observed NO-Fe(III)porphyrin intermediate. Nitrosylation rates were obtained and compared in aqueous buffer and in micellar systems. Monomers nitrosylate much faster than micro-oxo-dimers. Oppositely charged micelles prevent nitrosylation of the iron-porphyrins or considerably enhance nitrosylation times. Nitrosylation rates are comparable to transnitrosylation rates between several S-nitrosothiols and thiol-containing proteins, suggesting biological relevance for the process. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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