Microperoxidase-11 (MP11) is an undecapeptide derived from horse heart cytochrome c (cyt c) and characterized by a covalently-linked solvent-exposed heme group. Here, kinetics of the NO2--mediated nitrosylation of ferrous MP11 (MP11-Fe(II)) is reported. Data were obtained between pH 6.4 and 8.2, at 20.0 degrees C. The NO2--mediated conversion conversion of MP11-Fe(II) to MP11-Fe(II)-NO requires one proton; accordingly, values of the apparent second-order rate constant (k(on)) decrease by about two orders of magnitude from (2.9 +/- 03) x 10(1) M-1 s(-1) to (5.0 +/- 0.6) x 10(-1) M-1 s(-1) upon increasing pH from 6.4 to pH 82. The slope of the linear fitting of Logk(on) versus pH is -1.00 +/- 0.06. Values of k(on), for the NO2--mediated nitrosylation of MP11-Fe(II) are similar to those of penta-coordinated cardiolipin-bound horse heart cyt c, exceeding by about two orders of magnitude those of wild-type horse heart cyt c. Present results highlight the role of heme distal residues in modulating horse heart cyt c reactivity.
Ascenzi, P., Sbardella, D., Fiocchetti, M., Santucci, R., Coletta, M. (2015). NO2(-)-mediated nitrosylation of ferrous microperoxidase-11. JOURNAL OF INORGANIC BIOCHEMISTRY, 153, 121-127 [10.1016/j.jinorgbio.2015.06.022].
NO2(-)-mediated nitrosylation of ferrous microperoxidase-11.
ASCENZI, Paolo;FIOCCHETTI, MARCO;
2015-01-01
Abstract
Microperoxidase-11 (MP11) is an undecapeptide derived from horse heart cytochrome c (cyt c) and characterized by a covalently-linked solvent-exposed heme group. Here, kinetics of the NO2--mediated nitrosylation of ferrous MP11 (MP11-Fe(II)) is reported. Data were obtained between pH 6.4 and 8.2, at 20.0 degrees C. The NO2--mediated conversion conversion of MP11-Fe(II) to MP11-Fe(II)-NO requires one proton; accordingly, values of the apparent second-order rate constant (k(on)) decrease by about two orders of magnitude from (2.9 +/- 03) x 10(1) M-1 s(-1) to (5.0 +/- 0.6) x 10(-1) M-1 s(-1) upon increasing pH from 6.4 to pH 82. The slope of the linear fitting of Logk(on) versus pH is -1.00 +/- 0.06. Values of k(on), for the NO2--mediated nitrosylation of MP11-Fe(II) are similar to those of penta-coordinated cardiolipin-bound horse heart cyt c, exceeding by about two orders of magnitude those of wild-type horse heart cyt c. Present results highlight the role of heme distal residues in modulating horse heart cyt c reactivity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
