Linked Life Data

11851414

Source:http://linkedlifedata.com/resource/pubmed/id/11851414

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2002-2-19
pubmed:abstractText
We have used cryogenic difference FTIR and time-resolved step-scan Fourier transform infrared (TR-FTIR) spectroscopies to explore the redox-linked proton-pumping mechanism of heme-copper respiratory oxidases. These techniques are used to probe the structure and dynamics of the heme a(3)-Cu(B) binuclear center and the coupled protein structures in response to the photodissociation of CO from heme Fe and its subsequent binding to and dissociation from Cu(B). Previous cryogenic (80 K) FTIR CO photodissociation difference results were obtained for cytochrome bo(3), the ubiquinol oxidase of Escherichia coli [Puustinen, A., et al. (1997) Biochemistry 36, 13195-13200]. These data revealed a connectivity between Cu(B) and glutamic acid E286, a residue which has been implicated in proton pumping. In the current work, the same phenomenon is observed using the CO adduct of bovine cytochrome aa(3) under cryogenic conditions, showing a perturbation of the equivalent residue (E242) to that in bo(3). Furthermore, using time-resolved (5 micros resolution) step-scan FTIR spectroscopy at room temperature, we observe the same spectroscopic perturbation in both cytochromes aa(3) and bo(3). In addition, we observe evidence for perturbation of a second carboxylic acid side chain, at higher frequency in both enzymes at room temperature. The high-frequency feature does not appear in the cryogenic difference spectra, indicating that the perturbation is an activated process. We postulate that the high-frequency IR feature is due to the perturbation of E62 (E89 in bo(3)), a residue near the opening of the proton K-channel and required for enzyme function. The implications of these results with respect to the proton-pumping mechanism are discussed. Finally, a fast loss of over 60% of the Cu(B)-CO signal in bo(3) is observed and ascribed to one or more additional conformations of the enzyme. This fast conformer is proposed to account for the uninhibited reaction with O(2) in flow-flash experiments.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
41
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2675-83
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Time-resolved step-scan Fourier transform infrared spectroscopy of the CO adducts of bovine cytochrome c oxidase and of cytochrome bo(3) from Escherichia coli.
pubmed:affiliation
Los Alamos National Laboratory, Bioscience Division, Michelson Resource, Mail Stop J586, Los Alamos, New Mexico 87545, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.