The Nitric Oxide Reductase Mechanism of Flavo-diiron Proteins

dc.contributor.advisorKurtz, Jr., Donald M.
dc.contributor.authorCaranto, Jonathan Douglas
dc.contributor.committeeMemberJarrett, Harry W.
dc.contributor.committeeMemberMusie, Ghezai T.
dc.contributor.committeeMemberTonzetich, Zachary J.
dc.date.accessioned2024-02-09T19:29:12Z
dc.date.available2024-02-09T19:29:12Z
dc.date.issued2013
dc.descriptionThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.
dc.description.abstractFlavo-diiron proteins (FDPs) contain both a non-heme diiron site and a flavin-mononucleotide binding domain. FDPs are widespread in O<sub>2</sub>-sensitive bacteria, archaea and also a few protozoan parasites. FDPs are implicated as oxidative or nitrosative stress protection enzymes. In some organisms, FDPs provide both protections. Biochemical evidence indicates that FDPs are the terminal components of a reductive dioxygen and/or nitric oxide scavenging pathway: O<sub>2</sub> + 4 e<super>-</super> + 4 H<super>+</super> &rarr; 2 H<sub>2</sub>O 2 NO + 2 e<super>-</super> + 2 H<super>+</super> &rarr; N<sub>2</sub>O + H<sub>2</sub>O The following research focused on characterizing the FDP NOR mechanism. Steady-state activity assays provide little information about NOR pathway intermediates and thus, rapid-mixing techniques were used to obtain pre-steady state kinetics and spectroscopic features of intermediates along the NOR pathway. The NOR pathway was determined to proceed via an antiferromagnetically coupled diferrous-dinitrosyl intermediate and does not require FMNH<sub>2</sub> to catalyze N-N bond formation. The implication of this work on diiron site reactivity towards NO reduction is discussed. In addition to the wild-type enzyme, FDP from Thermotoga maritima was mutated so as to replace an iron-coordinating histidine with either a weaker donor (asparagine) or a non-coordinating residue (alanine). Surprisingly, the steady-state and pre-steady-state O<sub>2</sub>R and NOR activities did not exhibit significant changes compared to the wild-type protein.
dc.description.departmentChemistry
dc.format.extent219 pages
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/20.500.12588/2925
dc.languageen
dc.subjectFlavo-diiron protein
dc.subjectnitric oxide
dc.subjectnon-heme iron
dc.subject.classificationChemistry
dc.subject.classificationBiochemistry
dc.subject.classificationInorganic chemistry
dc.titleThe Nitric Oxide Reductase Mechanism of Flavo-diiron Proteins
dc.typeThesis
dc.type.dcmiText
dcterms.accessRightspq_closed
thesis.degree.departmentChemistry
thesis.degree.grantorUniversity of Texas at San Antonio
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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