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- Title
Reductive nitrosylation of ferric human serum heme-albumin.
- Authors
Ascenzi, Paolo; Yu Cao; di Masi, Alessandra; Gullotta, Francesca; De Sanctis, Giampiero; Fanali, Gabriella; Fasano, Mauro; Coletta, Massimo
- Abstract
Heme endows human serum albumin (HSA) with heme-protein-like reactivity and spectroscopic properties. Here, the kinetics and thermodynamics of reductive nitrosylation of ferric human serum heme-albumin [HSA-heme-Fe(III)] are reported. All data were obtained at 20 °C. At pH 5.5, HSA-heme-Fe(III) binds nitrogen monoxide (NO) reversibly, leading to the formation of nitrosylated HSA-heme-Fe(III) [HSA-heme-Fe(III)-NO]. By contrast, at pH ≥ 6.5, the addition of NO to HSA-heme-Fe(III) leads to the transient formation of HSA-heme-Fe(III)-NO in equilibrium with HSA-heme-Fe(II)-NO+. Then, HSA-heme-Fe(II)-NO+ undergoes nucleophilic attack by OH− to yield ferrous human serum heme-albumin [HSA-heme-Fe(II)]. HSA-heme-Fe(II) further reacts with NO to give nitrosylated HSA-heme-Fe(II) [HSA-heme-Fe(II)-NO]. The rate-limiting step for reductive nitrosylation of HSA-heme-Fe(III) is represented by the OH−-mediated reduction of HSA-heme-Fe(II)-NO+ to HSA-heme-Fe(II). The value of the second-order rate constant for OH−-mediated reduction of HSA-heme-Fe(II)-NO+ to HSA-heme-Fe(II) is 4.4 × 103 m−1·s−1. The present results highlight the role of HSA-heme-Fe in scavenging reactive nitrogen species.
- Subjects
ALBUMINS; BLOOD plasma; HYDROGEN-ion concentration; SERUM albumin; BLOOD proteins
- Publication
FEBS Journal, 2010, Vol 277, Issue 11, p2474
- ISSN
1742-464X
- Publication type
Article
- DOI
10.1111/j.1742-4658.2010.07662.x