Peroxynitrite scavenging by ferryl sperm whale myoglobin and human hemoglobin.
Globins protect from the oxidative and nitrosative cell damage. Here, kinetics of peroxynitrite scavenging by ferryl sperm whale myoglobin (MbFe(IV)O) and human hemoglobin (HbFe(IV)O), between pH 5.8 and 8.3 at 20.0 degrees C, are reported. In the absence of CO(2), values of the second-order rate constant for peroxynitrite scavenging by MbFe(IV)O and HbFe(IV)O (i.e., for MbFe(III) and HbFe(III) formation; k(on)) are 4.6 x 10(4)M(-1)s(-1) and 3.3 x 10(4)M(-1)s(-1), respectively, at pH 7.1. Values of k(on) increase on decreasing pH with pK(a) values of 6.9 and 6.7, this suggests that the ONOOH species reacts preferentially with MbFe(IV)O and HbFe(IV)O. In the presence of CO(2) (=1.2 x 10(-3)M), values of k(on) for peroxynitrite scavenging by MbFe(IV)O and HbFe(IV)O are essentially pH-independent, the average k(on) values are 7.1 x 10(4)M(-1)s(-1) and 1.2 x 10(5)M(-1)s(-1), respectively. As a whole, MbFe(IV)O and HbFe(IV)O, obtained by treatment with H(2)O(2), undertake within the same cycle H(2)O(2) and peroxynitrite detoxification.
Ascenzi
Paolo
P
Department of Biology and Interdepartmental Laboratory for Electron Microscopy, University Roma Tre, I-00146 Roma, Italy. ascenzi@uniroma3.it
De Marinis
Elisabetta
E
di Masi
Alessandra
A
Ciaccio
Chiara
C
Coletta
Massimo
M
D000818:Animals; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000378:metabolism; D051379:Mice; D009211:Myoglobin / Q000378:metabolism*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000378:metabolism*; D050661:Sperm Whale / Q000378:metabolism*
D006454:Hemoglobins; D009211:Myoglobin; C066317:ferryl iron; D030421:Peroxynitrous Acid; D007501:Iron