Linked Life Data

17014090

Source:http://linkedlifedata.com/resource/pubmed/id/17014090

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2006-10-3
pubmed:abstractText
In Sphingomonas CHY-1, a single ring-hydroxylating dioxygenase is responsible for the initial attack of a range of polycyclic aromatic hydrocarbons (PAHs) composed of up to five rings. The components of this enzyme were separately purified and characterized. The oxygenase component (ht-PhnI) was shown to contain one Rieske-type [2Fe-2S] cluster and one mononuclear Fe center per alpha subunit, based on EPR measurements and iron assay. Steady-state kinetic measurements revealed that the enzyme had a relatively low apparent Michaelis constant for naphthalene (K(m) = 0.92 +/- 0.15 microM) and an apparent specificity constant of 2.0 +/- 0.3 mM(-)(1) s(-)(1). Naphthalene was converted to the corresponding 1,2-dihydrodiol with stoichiometric oxidation of NADH. On the other hand, the oxidation of eight other PAHs occurred at slower rates and with coupling efficiencies that decreased with the enzyme reaction rate. Uncoupling was associated with hydrogen peroxide formation, which is potentially deleterious to cells and might inhibit PAH degradation. In single turnover reactions, ht-PhnI alone catalyzed PAH hydroxylation at a faster rate in the presence of organic solvent, suggesting that the transfer of substrate to the active site is a limiting factor. The four-ring PAHs chrysene and benz[a]anthracene were subjected to a double ring-dihydroxylation, giving rise to the formation of a significant proportion of bis-cis-dihydrodiols. In addition, the dihydroxylation of benz[a]anthracene yielded three dihydrodiols, the enzyme showing a preference for carbons in positions 1,2 and 10,11. This is the first characterization of a dioxygenase able to dihydroxylate PAHs made up of four and five rings.
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
10
pubmed:volume
45
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12380-91
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Characterization of a naphthalene dioxygenase endowed with an exceptionally broad substrate specificity toward polycyclic aromatic hydrocarbons.
pubmed:affiliation
CEA, DSV, DRDC, Lab. Biochim. Biophys. Syst. Intégrés, CNRS, UMR 5092, F-38054 Grenoble, France. yves.jouanneau@cea.fr
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't