Linked Life Data

16201753

Source:http://linkedlifedata.com/resource/pubmed/id/16201753

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2005-10-5
pubmed:abstractText
The Mo(V) center of plant sulfite oxidase from Arabidopsis thaliana (At-SO) has been studied by continuous wave and pulsed EPR methods. Three different Mo(V) EPR signals have been observed, depending on pH and the technique used to generate the Mo(V) oxidation state. At pH 6, reduction by sulfite followed by partial reoxidation with ferricyanide generates an EPR spectrum with g-values similar to the low-pH (lpH) form of vertebrate SOs, but no nearby exchangeable protons can be detected. On the other hand, reduction of At-SO with Ti(III) citrate at pH 6 generates a Mo(V) signal with large hyperfine splittings from a single exchangeable proton, as is typically observed for lpH SO from vertebrates. Reduction of At-SO with sulfite at high pH generates the well-known high-pH (hpH) signal common to all sulfite oxidizing enzymes. It is proposed that, depending on the conformation of Arg374, the active site of At-SO may be in "closed" or "open" forms that differ in the degree of accessibility of the Mo center to substrate and water molecules. It is suggested that at low pH the sulfite-reduced At-SO has coordinated sulfate and is in the "closed form". Reoxidation to Mo(V) by ferricyanide leaves bound sulfate trapped at the active site, and consequently, there are no ligands with exchangeable protons. Reduction with Ti(III) citrate injects an electron directly into the active site to generate the [Mo(V)[triple bond]O(OH)]2+ unit that is well-known from model chemistry and which has a single exchangeable proton with a large isotropic hyperfine interaction. At high pH, the active site is in the "open form", and water can readily exchange into the site to generate the hpH SO.
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
11
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13274-81
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Structures of the Mo(V) forms of sulfite oxidase from Arabidopsis thaliana by pulsed EPR spectroscopy.
pubmed:affiliation
Department of Chemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721-0041, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, N.I.H., Extramural