• Login
    View Item 
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UMB Digital ArchiveCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    Display statistics

    Formation of the reactive iron-oxo intermediate during the biosynthesis of nitric oxide by neuronal nitric oxide synthase and its possible mechanism in the generation of secondary free radicals

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Find Full text
    Author
    Porasuphatana, Supatra
    Advisor
    Rosen, Gerald M., Ph.D., J.D.
    Date
    2001
    Type
    dissertation
    
    Metadata
    Show full item record
    Abstract
    Nitric oxide synthases (NOSs) are hemoproteins that catalyze the formation of nitric oxide (NO•) and L-citrulline from L-arginine by a five-electron oxidation reaction. All NOS isoforms are in the same superfamily and share structural similarities with cytochrome P-450. The generation of free radicals by NOS is primarily regulated by the binding of L-arginine. During the oxidation of L-arginine to generate NO•, the transfer of electrons from reductase to oxygenase domain of NOS leads to changes in the oxidation state of heme iron, resulting in the formation of the perferryl iron-oxo intermediate of NOS (NOS-[Fe5+=O]3+). This dissertation aims to explore the possible role of NOS-[Fe5+=O]3+ in the generation of secondary free radicals. The NOS-[Fe5+=O] 3+, which formed only when L-arginine bound to the enzyme, was proven to abstract a hydrogen atom from substrates to generate carbon-centered free radicals. It was demonstrated that the abstraction of hydrogen atom by NOS-[Fe 5+=O]3+ occurred at a carbon alpha to a heteroatom, similar to hydroxylation reaction catalyzed by cytochrome P-450. Further investigation using potassium hydrogen persulfate (KHSO5) confirmed the formation of NOS-[Fe5+=O]3+ which may be generated via the rearrangement of NOS-[Fe3+-O-O-SO 3-] following the transfer of oxygen from KHSO 5 to NOS I. The NOS-[Fe5+=O]3+ generated by KHSO5-catalyzed NOS I was shown to generate NO• from L-arginine and alpha-hydroxyethyl radical from ethanol, resembling the incidences found with the NADPH/O2 NOS as a source of substrate oxidation. Deuterium isotope effect, using unlabeled ethanol and ethyl 1,1-d2 alcohol, revealed the importance of the breakage of C1-H bond as a partial rate-limiting step for the formation of carbon-centered free radicals by NOS. Taken together, this research illustrates the contribution of L-arginine binding to the formation of NOS reactive iron-oxo complex intermediate and the role of the iron complex in the generation of carbon-centered free radicals by the hydrogen atom abstraction.
    Description
    University of Maryland, Baltimore. Pharmaceutical Sciences. Ph.D. 2001
    Keyword
    Health Sciences, Pharmacology
    Identifier to cite or link to this item
    http://hdl.handle.net/10713/1212
    Collections
    Theses and Dissertations School of Pharmacy
    Theses and Dissertations All Schools

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Policies | Contact Us | UMB Health Sciences & Human Services Library
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.