Reductive nitrosylation of ferric human serum heme-albumin.

Ascenzi, P; Cao, Y; Di Masi, A; Gullotta, F; De Sanctis, Giampiero; Fanali, G; Fasano, M; Coletta, M.

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 degrees 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 >or= 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 x 10(3) M(-1) s(-1). The present results highlight the role of HSA-heme-Fe in scavenging reactive nitrogen species.

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Titolo:	Reductive nitrosylation of ferric human serum heme-albumin.
Autori:	ASCENZI P CAO Y DI MASI A GULLOTTA F DE SANCTIS, Giampiero FANALI G FASANO M COLETTA M. mostra contributor esterni nascondi contributor esterni
Data di pubblicazione:	2010
Rivista:	THE FEBS JOURNAL
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 degrees 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 >or= 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 x 10(3) M(-1) s(-1). The present results highlight the role of HSA-heme-Fe in scavenging reactive nitrogen species.
Handle:	http://hdl.handle.net/11581/200795
Appare nelle tipologie:	Articolo

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