Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1935089 | Biochemical and Biophysical Research Communications | 2008 | 5 Pages |
Abstract
Kinetics of ferric Mycobacterium leprae truncated hemoglobin O (trHbOFe(III)) oxidation by H2O2 and of trHbOFe(IV)O reduction by NO and NO2â are reported. The value of the second-order rate constant for H2O2-mediated oxidation of trHbOFe(III) is 2.4Â ÃÂ 103Â Mâ1Â sâ1. The value of the second-order rate constant for NO-mediated reduction of trHbOFe(IV)O is 7.8Â ÃÂ 106Â Mâ1Â sâ1. The value of the first-order rate constant for trHbOFe(III)ONO decay to the resting form trHbOFe(III) is 2.1Â ÃÂ 101Â sâ1. The value of the second-order rate constant for NO2â-mediated reduction of trHbOFe(IV)O is 3.1Â ÃÂ 103Â Mâ1Â sâ1. As a whole, trHbOFe(IV)O, generated upon reaction with H2O2, catalyzes NO reduction to NO2â. In turn, NO and NO2â act as antioxidants of trHbOFe(IV)O, which could be responsible for the oxidative damage of the mycobacterium. Therefore, Mycobacterium leprae trHbO could be involved in both H2O2 and NO scavenging, protecting from nitrosative and oxidative stress, and sustaining mycobacterial respiration.
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Authors
Paolo Ascenzi, Elisabetta De Marinis, Massimo Coletta, Paolo Visca,