Linked Life Data

16502006

Source:http://linkedlifedata.com/resource/pubmed/id/16502006

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2006-4-4
pubmed:abstractText
Acetylcoenzyme A synthase/carbon monoxide dehydrogenase (ACS/CODH) contains two Ni-Fe-S active-site clusters (called A and C) connected by a tunnel through which CO and CO2 migrate. Site-directed mutants A578C, L215F, and A219F were designed to block the tunnel at different points along the region between the two C-clusters. Two other mutant proteins F70W and N101Q were designed to block the region that connects the tunnel at the betabeta interface with a water channel also located at that interface. Purified mutant proteins were assayed for Ni/Fe content and examined by electron paramagnetic resonance spectroscopy. Analyses indicate that same metal clusters found in wild-type (WT) ACS/CODH (i.e., the A-, B-, C-, and probably D-clusters) are properly assembled in the mutant enzymes. Stopped-flow kinetics revealed that these centers in the mutants are rapidly reducible by dithionite but are only slowly reducible by CO, suggesting an impaired ability of CO to migrate through the tunnel to the C-cluster. Relative to the WT enzyme, mutant proteins exhibited little CODH or ACS activity (using CO2 as a substrate). Some ACS activity was observed when CO was a substrate, but not the cooperative CO inhibition effect characteristic of WT ACS/CODH. These results suggest that CO and CO2 enter and exit the enzyme at the water channel along the betabeta subunit interface. They also suggest two pathways for CO during synthesis of acetylcoenzyme A, including one in which CO enters the enzyme and migrates through the tunnel before binding at the A-cluster, and another in which CO binds the A-cluster directly from the solvent.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0949-8257
pubmed:author
pubmed:issnType
Print
pubmed:volume
11
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
371-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Function of the tunnel in acetylcoenzyme A synthase/carbon monoxide dehydrogenase.
pubmed:affiliation
Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural