Linked Life Data

16966328

Source:http://linkedlifedata.com/resource/pubmed/id/16966328

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
45
pubmed:dateCreated
2006-11-6
pubmed:abstractText
The crystal structure of the neuronal nitric-oxide synthase (nNOS) NADPH/FAD binding domain indicated that Ser-1176 is within hydrogen bonding distance of Asp-1393 and the O4 atom of FAD and is also near the N5 atom of FAD (3.7 A). This serine residue is conserved in most of the ferredoxin-NADP+ reductase family of proteins and is important in electron transfer. In the present study, the homologous serines of both nNOS (Ser-1176) and endothelial nitric-oxide synthase (eNOS) (Ser-942) were mutated to threonine and alanine. Both substitutions yielded proteins that exhibited decreased rates of electron transfer through the flavin domains, in the presence and absence of Ca2+/CaM, as measured by reduction of potassium ferricyanide and cytochrome c. Rapid kinetics measurements of flavin reduction of all the mutants also showed a decrease in the rate of flavin reduction, in the absence and presence of Ca2+/CaM, as compared with the wild type proteins. The serine to alanine substitution caused both nNOS and eNOS to synthesize NO more slowly; however, the threonine mutants gave equal or slightly higher rates of NO production compared with the wild type enzymes. The midpoint redox potential measurements of all the redox centers revealed that wild type and threonine mutants of both nNOS and eNOS are very similar. However, the redox potentials of the FMN/FMNH* couple for alanine substitutions of both nNOS and eNOS are >100 mV higher than those of wild type proteins and are positive. These data presented here suggest that hydrogen bonding of the hydroxyl group of serine or threonine with the isoalloxazine ring of FAD and with the amino acids in its immediate milieu, particularly nNOS Asp-1393, affects the redox potentials of various flavin states, influencing the rate of electron transfer.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
281
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
34246-57
pubmed:dateRevised
2007-12-3
pubmed:meshHeading
pubmed-meshheading:16966328-Alanine, pubmed-meshheading:16966328-Amino Acid Sequence, pubmed-meshheading:16966328-Amino Acid Substitution, pubmed-meshheading:16966328-Calcium, pubmed-meshheading:16966328-Calmodulin, pubmed-meshheading:16966328-Catalysis, pubmed-meshheading:16966328-Electron Transport, pubmed-meshheading:16966328-Flavin-Adenine Dinucleotide, pubmed-meshheading:16966328-Humans, pubmed-meshheading:16966328-Hydrogen Bonding, pubmed-meshheading:16966328-Molecular Sequence Data, pubmed-meshheading:16966328-Mutagenesis, Site-Directed, pubmed-meshheading:16966328-Mutation, pubmed-meshheading:16966328-NADP, pubmed-meshheading:16966328-Nitric Oxide Synthase Type I, pubmed-meshheading:16966328-Nitric Oxide Synthase Type III, pubmed-meshheading:16966328-Oxidation-Reduction, pubmed-meshheading:16966328-Polymerase Chain Reaction, pubmed-meshheading:16966328-Sequence Homology, Amino Acid, pubmed-meshheading:16966328-Serine, pubmed-meshheading:16966328-Threonine
pubmed:year
2006
pubmed:articleTitle
The role of a conserved serine residue within hydrogen bonding distance of FAD in redox properties and the modulation of catalysis by Ca2+/calmodulin of constitutive nitric-oxide synthases.
pubmed:affiliation
Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural