Linked Life Data

11669618

Source:http://linkedlifedata.com/resource/pubmed/id/11669618

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
43
pubmed:dateCreated
2001-10-23
pubmed:abstractText
In nitric oxide synthase (NOS), (6R)-tetrahydrobiopterin (H(4)B) binds near the heme and can reduce a heme-dioxygen intermediate (Fe(II)O(2)) during Arg hydroxylation [Wei, C.-C., Wang, Z.-Q., Wang, Q., Meade, A. L., Hemann, C., Hille, R., and Stuehr, D. J. (2001) J. Biol. Chem. 276, 315-319]. A conserved Trp engages in aromatic stacking with H(4)B, and its mutation inhibits NO synthesis. To examine how this W457 impacts H(4)B redox function, we performed single turnover reactions with the mouse inducible NOS oxygenase domain (iNOSoxy) mutants W457F and W457A. Ferrous mutants containing Arg and H(4)B were mixed with O(2)-containing buffer, and then heme spectral transitions, H(4)B radical formation, and Arg hydroxylation were followed versus time. A heme Fe(II)O(2) intermediate was observed in W457A and W457F and had normal spectral characteristics. However, its disappearance rate (6.5 s(-1) in W457F and 3.0 s(-1) in W457A) was slower than in wild-type (12.5 s(-1)). Rates of H(4)B radical formation (7.1 s(-1) in W457F and 2.7 s(-1) in W457A) matched their rates of Fe(II)O(2) disappearance, but were slower than radical formation in wild-type (13 s(-1)). The extent of H(4)B radical formation in the mutants was similar to wild-type, but their radical decayed 2-4 times faster. These kinetic changes correlated with slower and less extensive Arg hydroxylation by the mutants (wild-type > W457F > W457A). We conclude that W457 ensures a correct tempo of electron transfer from H(4)B to heme Fe(II)O(2), possibly by stabilizing the H(4)B radical. Proper control of these parameters may help maximize Arg hydroxylation and minimize uncoupled O(2) activation at the heme.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
30
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12819-25
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:11669618-Animals, pubmed-meshheading:11669618-Arginine, pubmed-meshheading:11669618-Biopterin, pubmed-meshheading:11669618-Conserved Sequence, pubmed-meshheading:11669618-Electron Spin Resonance Spectroscopy, pubmed-meshheading:11669618-Electrons, pubmed-meshheading:11669618-Heme, pubmed-meshheading:11669618-Kinetics, pubmed-meshheading:11669618-Light, pubmed-meshheading:11669618-Mice, pubmed-meshheading:11669618-Models, Chemical, pubmed-meshheading:11669618-Mutation, pubmed-meshheading:11669618-Nitric Oxide, pubmed-meshheading:11669618-Nitric Oxide Synthase, pubmed-meshheading:11669618-Nitric Oxide Synthase Type II, pubmed-meshheading:11669618-Oxygen, pubmed-meshheading:11669618-Protein Binding, pubmed-meshheading:11669618-Spectrophotometry, pubmed-meshheading:11669618-Time Factors, pubmed-meshheading:11669618-Tryptophan
pubmed:year
2001
pubmed:articleTitle
A conserved tryptophan in nitric oxide synthase regulates heme-dioxy reduction by tetrahydrobiopterin.
pubmed:affiliation
Department of Immunology, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.