Linked Life Data

6300101

Source:http://linkedlifedata.com/resource/pubmed/id/6300101

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1983-5-27
pubmed:abstractText
The binding of arsenite to the molybdenum center of milk xanthine oxidase is re-examined. The Kd for the arsenite complex has been determined to be 24 microM from equilibrium binding studies and this value has been confirmed by determination of the association and dissociation rate constants for the interaction of arsenite with xanthine oxidase. Formation of the complex is not prevented by prior reaction of the enzyme with thiol reagents such as 5,5'-dithiobis-(2-nitrobenzoic acid) or methyl methanethiosulfonate. Binding of arsenite to the enzyme perturbs both the oxidation-reduction potentials and the electron paramagnetic resonance signal of the molybdenum center observed after partial reduction of the enzyme with sodium dithionite. The EPR signal of the partially reduced arsenite-complexed enzyme is further modified in two different ways by the addition of xanthine or salicylate. Other purine and pteridine substrates and products for the enzyme yield EPR signals indistinguishable from that generated by xanthine, whereas aromatic aldehydes and carboxylic acids give signals similar to that observed in the presence of salicylate. It is thus clear that while arsenite prevents enzyme turnover, it does not preclude binding of substrate and product molecules. Binding of arsenite at the molybdenum center of xanthine oxidase does not disturb the oxidation-reduction potentials of the iron-sulfur centers of the enzyme, but evidence is presented to suggest that the midpoint potential of the FAD site is decreased by approximately 15 mV. A structure for the arsenite complex is proposed to provide a framework in which to interpret the EPR signals in a quantitative fashion.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
258
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4849-56
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
The interaction of arsenite with xanthine oxidase.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.