Hemopexin (HPX) serves as a trap for toxic plasma heme, ensuring its complete clearance by transportation to the liver. Moreover, HPX-heme has been postulated to play a key role in the homeostasis of nitric oxide (NO). Here, the thermodynamics for NO binding to rabbit ferrous HPX-heme as well as the EPR and optical absorption spectroscopic properties of rabbit ferrous nitrosylated HPX-heme (HPX-heme-NO) are reported. The value of the dissociation equilibrium constant for NO binding to rabbit ferrous HPX-heme (i.e., H) is (1.4+/-0.2)x10(-7) M, at pH 7.0 and 10.0degreesC; the value of H is unaffected by sodium chloride. At pH 7.0, rabbit ferrous HPX-heme-NO is a six-coordinate heme-iron species, characterized by an X-band EPR spectrum with an axial geometry and by epsilon=146 mM(-1) cm(-1) at 419 nm. At pH 4.0, rabbit ferrous HPX-heme-NO is a five-coordinate heme-iron species, characterized by an X-band EPR spectrum with three-line splitting centered at 334 mT and by epsilon=74 mM(-1) cm(-1) at 387 nm. The pK(a) value of the reversible pH-induced six- to five-coordinate spectroscopic transition is 4.8+/-0.1 in the absence of sodium chloride and 4.3+/-0.1 in the presence of 1.5x10(-1) M sodium chloride. This result is in agreement with the effect of sodium chloride on rabbit HPX-heme stability. The present data have been analyzed in parallel with those of a related heme model compound and heme-protein systems.

Fasano, M., Bocedi, A., Mattu, M., Coletta, M., Ascenzi, P. (2004). Nitrosylation of rabbit ferrous heme-hemopexin. JBIC, 9(7), 800-806 [10.1007/s00775-004-0598-0].

Nitrosylation of rabbit ferrous heme-hemopexin

Bocedi A.;COLETTA, MASSIMILIANO;
2004-01-01

Abstract

Hemopexin (HPX) serves as a trap for toxic plasma heme, ensuring its complete clearance by transportation to the liver. Moreover, HPX-heme has been postulated to play a key role in the homeostasis of nitric oxide (NO). Here, the thermodynamics for NO binding to rabbit ferrous HPX-heme as well as the EPR and optical absorption spectroscopic properties of rabbit ferrous nitrosylated HPX-heme (HPX-heme-NO) are reported. The value of the dissociation equilibrium constant for NO binding to rabbit ferrous HPX-heme (i.e., H) is (1.4+/-0.2)x10(-7) M, at pH 7.0 and 10.0degreesC; the value of H is unaffected by sodium chloride. At pH 7.0, rabbit ferrous HPX-heme-NO is a six-coordinate heme-iron species, characterized by an X-band EPR spectrum with an axial geometry and by epsilon=146 mM(-1) cm(-1) at 419 nm. At pH 4.0, rabbit ferrous HPX-heme-NO is a five-coordinate heme-iron species, characterized by an X-band EPR spectrum with three-line splitting centered at 334 mT and by epsilon=74 mM(-1) cm(-1) at 387 nm. The pK(a) value of the reversible pH-induced six- to five-coordinate spectroscopic transition is 4.8+/-0.1 in the absence of sodium chloride and 4.3+/-0.1 in the presence of 1.5x10(-1) M sodium chloride. This result is in agreement with the effect of sodium chloride on rabbit HPX-heme stability. The present data have been analyzed in parallel with those of a related heme model compound and heme-protein systems.
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/10
English
heme derivative; hemopexin; hemoprotein; iron; nitric oxide; sodium chloride; absorption spectroscopy; article; dissociation; electron spin resonance; geometry; nitrosylation; pH; priority journal; thermodynamics; Animals; Electron Spin Resonance Spectroscopy; Ferrous Compounds; Heme; Hemopexin; Hydrogen-Ion Concentration; Models, Molecular; Nitrates; Nitric Oxide; Protein Binding; Protein Conformation; Rabbits; Thermodynamics; Oryctolagus cuniculus
Fasano, M., Bocedi, A., Mattu, M., Coletta, M., Ascenzi, P. (2004). Nitrosylation of rabbit ferrous heme-hemopexin. JBIC, 9(7), 800-806 [10.1007/s00775-004-0598-0].
Fasano, M; Bocedi, A; Mattu, M; Coletta, M; Ascenzi, P
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/29345
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