During infection, Mycobacterium leprae is faced with the host macrophagic environment limiting the growth of the bacilli. However, (pseudo-)enzymatic detoxification systems, including truncated hemoglobin O (Ml-trHbO), could allow this mycobacterium to persist in vivo. Here, kinetics of peroxynitrite (ONOOH/ONOO-) detoxification by ferryl Ml-trHbO (Ml-trHbO-Fe(IV)=O), obtained by treatment with H2O2, is reported. Values of the second-order rate constant for peroxynitrite detoxification by Ml-trHbO-Fe(IV)=O (i.e., of Ml-trHbO-Fe(III) formation; k(on)), at pH 7.2 and 22.0 degrees C, are 1.5 x 10(4) M (1) s(-1), and 2.2, 10(4) M-1 s(-1), in the absence of and presence of physiological levels of CO2 (similar to 1.2 x 10(-3) M), respectively. Values of k(on) increase on decreasing pH with a pK(a) value of 6.7. this suggests that ONOOH reacts preferentially with Ml-trHbO-Fe(IV)=O. In turn, peroxynitrite acts as an antioxidant of Ml-trHbO-Fe(IV)=O, which could be responsible for the oxidative damage of the mycobacterium. As a whole, Ml-trHbO can undertake within the same cycle H2O2 and peroxynitrite detoxification. (C) 2009 Elsevier Inc. All rights reserved.

Ascenzi P., D.M.E. (2009). Peroxynitrite detoxification by ferryl Mycobacterium leprae truncated hemoglobin O. BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 380(2), 392-396 [10.1016/j.bbrc.2009.01.088].

Peroxynitrite detoxification by ferryl Mycobacterium leprae truncated hemoglobin O

CIACCIO, CHIARA;COLETTA, MASSIMILIANO
2009

Abstract

During infection, Mycobacterium leprae is faced with the host macrophagic environment limiting the growth of the bacilli. However, (pseudo-)enzymatic detoxification systems, including truncated hemoglobin O (Ml-trHbO), could allow this mycobacterium to persist in vivo. Here, kinetics of peroxynitrite (ONOOH/ONOO-) detoxification by ferryl Ml-trHbO (Ml-trHbO-Fe(IV)=O), obtained by treatment with H2O2, is reported. Values of the second-order rate constant for peroxynitrite detoxification by Ml-trHbO-Fe(IV)=O (i.e., of Ml-trHbO-Fe(III) formation; k(on)), at pH 7.2 and 22.0 degrees C, are 1.5 x 10(4) M (1) s(-1), and 2.2, 10(4) M-1 s(-1), in the absence of and presence of physiological levels of CO2 (similar to 1.2 x 10(-3) M), respectively. Values of k(on) increase on decreasing pH with a pK(a) value of 6.7. this suggests that ONOOH reacts preferentially with Ml-trHbO-Fe(IV)=O. In turn, peroxynitrite acts as an antioxidant of Ml-trHbO-Fe(IV)=O, which could be responsible for the oxidative damage of the mycobacterium. As a whole, Ml-trHbO can undertake within the same cycle H2O2 and peroxynitrite detoxification. (C) 2009 Elsevier Inc. All rights reserved.
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/10
English
Carbon dioxide; Detoxification of reactive nitrogen and oxygen species; Hydrogen peroxide; Mycobacterium leprae; Peroxynitrite; Truncated hemoglobin O
Ascenzi P., D.M.E. (2009). Peroxynitrite detoxification by ferryl Mycobacterium leprae truncated hemoglobin O. BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 380(2), 392-396 [10.1016/j.bbrc.2009.01.088].
Ascenzi, P; De Marinis, E; Visca, P; Ciaccio, C; Coletta, M
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2108/41239
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