Linked Life Data

6643492

Source:http://linkedlifedata.com/resource/pubmed/id/6643492

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
1984-1-27
pubmed:abstractText
The reaction of oxygen with catechol 1,2-dioxygenase from Pseudomonas arvilla ATCC 23974 in complex with catechol, 4-methylcatechol, and 4-fluorocatechol has been studied using single turnover stopped flow spectrophotometry. Two sequential enzyme intermediates have been resolved and their visible spectra characterized by computer-assisted methods. These intermediates are spectrally similar to those observed in a similar study with protocatechuate dioxygenase (Bull, C., Ballou, D. P., and Otsuka, S. J. Biol. Chem. 256, 12681-12686 (1981), although the first intermediate seen with the latter enzyme was not observed in this study. The rate of formation of intermediate I is oxygen-dependent and also accelerated by electron-donating substituents on the C-4 of the substrate. This is consistent with the proposed substrate reduction of dioxygen to form a hydroperoxide. Intermediate I is thus suggested to be a 6-hydroperoxycyclohexa-3,5-diene-1-one. The decay of intermediate I is also accelerated by electron donors and is consistent with the rearrangement of intermediate hydroperoxide via an acyl migration mechanism. It is inconsistent with mechanisms involving nucleophilic attack at the carbonyl carbon. Intermediate II is proposed to be an enzyme-product complex based on the resemblance of its visible spectra to those of the benzoate complex of catechol 1,2-dioxygenase and enzyme-product complexes of protocatechuate dioxygenase. Careful 18O2-labeling experiments have shown that no label is lost to the solvent, implying that no free hydroxide forms during catalysis.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
258
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14422-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Rapid reaction studies on the oxygenation reactions of catechol dioxygenase.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.