title: Peroxynitrite scavenging by ferrous truncated hemoglobin GlbO from Mycobacterium leprae.
abstract: Mycobacterium leprae GlbO has been proposed to represent merging of both O(2) uptake/transport and scavenging of nitrogen reactive species. Peroxynitrite reacts with M. leprae GlbO(II)-NO leading to GlbO(III) via the GlbO(III)-NO species. The value of the second order rate constant for GlbO(III)-NO formation is >1x10(8)M(-1)s(-1) in the absence and presence of CO(2) (1.2x10(-3)M). The CO(2)-independent value of the first order rate constant for GlbO(III)-NO denitrosylation is (2.5+/-0.4)x10(1)s(-1). Furthermore, peroxynitrite reacts with GlbO(II)-O(2) leading to GlbO(III) via the GlbO(IV)O species. Values of the second order rate constant for GlbO(IV)O formation are (4.8+/-0.5)x10(4) and (6.3+/-0.7)x10(5)M(-1)s(-1) in the absence and presence of CO(2) (=1.2x10(-3)M), respectively. The value of the second order rate constant for the peroxynitrite-mediated GlbO(IV)O reduction (= (1.5+/-0.2)x10(4)M(-1)s(-1)) is CO(2)-independent. These data argue for a role of GlbO in the defense of M. leprae against nitrosative stress.
authors.affiliation: National Institute for Infectious Diseases I.R.C.C.S. Lazzaro Spallanzani, Via Portuense 292, I-00149 Roma, Italy. ascenzi@bio.uniroma3.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
authors.forename: Mario
authors.initials: M
authors.lastname: Milani
authors.forename: Paolo
authors.initials: P
authors.lastname: Visca
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002245:Carbon Dioxide / Q000494:pharmacology; D006454:Hemoglobins / Q000378:metabolism*; D007700:Kinetics; D009166:Mycobacterium leprae / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D054793:Truncated Hemoglobins
chemical_list: D001426:Bacterial Proteins; D006454:Hemoglobins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D054793:Truncated Hemoglobins; C460871:truncated hemoglobin, Mycobacterium leprae; D002245:Carbon Dioxide; D030421:Peroxynitrous Acid