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., B.A. (2004). Nitrosylation of rabbit ferrous heme-hemopexin. JBIC, 9(7), 800-806.
|Tipologia:||Articolo su rivista|
|Citazione:||Fasano M., B.A. (2004). Nitrosylation of rabbit ferrous heme-hemopexin. JBIC, 9(7), 800-806.|
|Settore Scientifico Disciplinare:||Settore BIO/10|
|Revisione (peer review):||Sì, ma tipo non specificato|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1007/s00775-004-0598-0|
|Stato di pubblicazione:||Pubblicato|
|Data di pubblicazione:||2004|
|Titolo:||Nitrosylation of rabbit ferrous heme-hemopexin|
|Autori:||Fasano M., Bocedi A., Mattu M., Coletta M., Ascenzi P.|
|Appare nelle tipologie:||01 - Articolo su rivista|