H2O2 and (.)NO scavenging by Mycobacterium leprae truncated hemoglobin O |
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Authors: | Ascenzi Paolo De Marinis Elisabetta Coletta Massimo Visca Paolo |
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Institution: | a Department of Biology and Interdepartmental Laboratory for Electron Microscopy, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy b National Institute for Infectious Diseases I.R.C.C.S. ‘Lazzaro Spallanzani’, Via Portuense 292, I-00149 Roma, Italy c Department of Experimental Medicine and Biochemical Sciences, University of Roma ‘Tor Vergata’, Via Montpellier 1, I-00133 Roma, Italy |
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Abstract: | Kinetics of ferric Mycobacterium leprae truncated hemoglobin O (trHbO Fe(III)) oxidation by H2O2 and of trHbO Fe(IV) O reduction by NO and NO2− are reported. The value of the second-order rate constant for H2O2-mediated oxidation of trHbO Fe(III) is 2.4 × 103 M−1 s−1. The value of the second-order rate constant for NO-mediated reduction of trHbO Fe(IV) O is 7.8 × 106 M−1 s−1. The value of the first-order rate constant for trHbO Fe(III) ONO decay to the resting form trHbO Fe(III) is 2.1 × 101 s−1. The value of the second-order rate constant for NO2−-mediated reduction of trHbO Fe(IV) O is 3.1 × 103 M−1 s−1. As a whole, trHbO Fe(IV) O, generated upon reaction with H2O2, catalyzes NO reduction to NO2−. In turn, NO and NO2− act as antioxidants of trHbO Fe(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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Keywords: | Fe(III) ferric heme-protein Fe(IV) length as m-dash" src="http://cdn els-cdn O" target="_blank">com/sd/entities/dbnd" class="glyphImg">O ferryl heme-protein Fe(III) els-cdn ONO" target="_blank">com/sd/entities/sbnd" class="glyphImg">ONO O-nitrito ferric heme-protein Hb hemoglobin Lb leghemoglobin Mb myoglobin TrHbO truncated Hb O |
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