Linked Life Data

8369306

Source:http://linkedlifedata.com/resource/pubmed/id/8369306

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
36
pubmed:dateCreated
1993-10-14
pubmed:abstractText
Biological reductive dehalogenation reactions are important in environmental detoxification of organohalides. Only scarce information is available on the enzymology underlying these reactions. Cytochrome P450CAM with a known X-ray structure and well-studied oxygenase reaction cycle, has been studied for its ability to reduce carbon-halogen bonds under anaerobic conditions. The reductive reactions functioned with NADH and the physiological electron-transfer proteins or by using artificial electron donors to reduce cytochrome P450CAM. Halogenated methane and ethane substrates were transformed by a two-electron reduction and subsequent protonation, beta-elimination, or alpha-elimination to yield alkanes, alkene, or carbene-derived products, respectively. Halogenated substrates bound to the camphor binding site as indicated by saturable changes in the Fe(III)-heme spin state upon substrate addition. Hexachloromethane was bound with a dissociation constant (KD) of 0.7 microM and caused > 95% shift from low- to high-spin iron. Ethanes bearing fewer chlorine substituents were bound with increasing dissociation constants and gave lesser degrees of iron spin-state change. Camphor competitively inhibited hexachloroethane reduction with an inhibitor constant (KI) similar to the dissociation constant for camphor (KI = KD = 0.9 microM). Rate determinations with pentachloroethane indicated a 100-fold higher enzyme V/K compared to the second-order rate constant for hematin free in solution. These studies on substrate binding and catalysis will help reveal how biological systems enzymatically reduce carbon-halogen bonds in the environment.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9355-61
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Reductive dehalogenation by cytochrome P450CAM: substrate binding and catalysis.
pubmed:affiliation
Department of Biochemistry, University of Minnesota, St. Paul 55108.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.