Linked Life Data

10998233

Source:http://linkedlifedata.com/resource/pubmed/id/10998233

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
36
pubmed:dateCreated
2000-10-13
pubmed:databankReference
pubmed:abstractText
We have investigated dynamic events after flash photolysis of CO from reduced cytochrome cd(1) nitrite reductase (NiR) from Paracoccus pantotrophus (formerly Thiosphaera pantotropha). Upon pulsed illumination of the cytochrome cd(1)-CO complex, at 460 nm, a rapid (<50 ns) absorbance change, attributed to dissociation of CO, was observed. This was followed by a biphasic rearrangement with rate constants of 1.7 x 10(4) and 2.5 x 10(3) s(-1) at pH 8.0. Both parts of the biphasic rearrangement phases displayed the same kinetic difference spectrum in the region of 400-660 nm. The slower of the two processes was accompanied by proton uptake from solution (0.5 proton per active site at pH 7.5-8.5). After photodissociation, the CO ligand recombined at a rate of 12 s(-1) (at 1 mM CO and pH 8.0), accompanied by proton release. The crystal structure of reduced cytochrome cd(1) in complex with CO was determined to a resolution of 1.57 A. The structure shows that CO binds to the iron of the d(1) heme in the active site. The ligation of the c heme is unchanged in the complex. A comparison of the structures of the reduced, unligated NiR and the NiR-CO complex indicates changes in the puckering of the d(1) heme as well as rearrangements in the hydrogen-bonding network and solvent organization in the substrate binding pocket at the d(1) heme. Since the CO ligand binds to heme d(1) and there are structural changes in the d(1) pocket upon CO binding, it is likely that the proton uptake or release observed after flash-induced CO dissociation is due to changes of the protonation state of groups in the active site. Such proton-coupled structural changes associated with ligand binding are likely to affect the redox potential of heme d(1) and may regulate the internal electron transfer from heme c to heme d(1).
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
12
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10967-74
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Proton-coupled structural changes upon binding of carbon monoxide to cytochrome cd1: a combined flash photolysis and X-ray crystallography study.
pubmed:affiliation
Department of Biochemistry, Uppsala University, Biomedical Center, Box 576, SE-751 23 Uppsala, Sweden.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't