Quantification of Local Electric Field Changes at the Active Site of Cytochrome c Oxidase by Fourier Transform Infrared Spectroelectrochemical Titrations

dc.contributor.authorBaserga, Federico
dc.contributor.authorDragelj, Jovan
dc.contributor.authorKozuch, Jacek
dc.contributor.authorMohrmann, Hendrik
dc.contributor.authorKnapp, Ernst-Walter
dc.contributor.authorStripp, Sven T.
dc.contributor.authorHeberle, Joachim
dc.date.accessioned2021-05-18T07:41:30Z
dc.date.available2021-05-18T07:41:30Z
dc.date.issued2021-04-27
dc.date.updated2021-05-11T07:53:34Z
dc.description.abstractCytochrome c oxidase (CcO) is a transmembrane protein complex that reduces molecular oxygen to water while translocating protons across the mitochondrial membrane. Changes in the redox states of its cofactors trigger both O2 reduction and vectorial proton transfer, which includes a proton-loading site, yet unidentified. In this work, we exploited carbon monoxide (CO) as a vibrational Stark effect (VSE) probe at the binuclear center of CcO from Rhodobacter sphaeroides. The CO stretching frequency was monitored as a function of the electrical potential, using Fourier transform infrared (FTIR) absorption spectroelectrochemistry. We observed three different redox states (R4CO, R2CO, and O), determined their midpoint potential, and compared the resulting electric field to electrostatic calculations. A change in the local electric field strength of +2.9 MV/cm was derived, which was induced by the redox transition from R4CO to R2CO. We performed potential jump experiments to accumulate the R2CO and R4CO species and studied the FTIR difference spectra in the protein fingerprint region. The comparison of the experimental and computational results reveals that the key glutamic acid residue E286 is protonated in the observed states, and that its hydrogen-bonding environment is disturbed upon the redox transition of heme a3. Our experiments also suggest propionate A of heme a3 changing its protonation state in concert with the redox state of a second cofactor, heme a. This supports the role of propionic acid side chains as part of the proton-loading site.en
dc.description.sponsorshipDFG, 221545957, SFB 1078: Proteinfunktion durch Protonierungsdynamiken
dc.identifier.eissn2296-2646
dc.identifier.urihttps://depositonce.tu-berlin.de/handle/11303/13117
dc.identifier.urihttp://dx.doi.org/10.14279/depositonce-11910
dc.language.isoenen
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en
dc.subject.ddc540 Chemie und zugeordnete Wissenschaftende
dc.subject.othervibrational Stark effecten
dc.subject.othercarbon monoxideen
dc.subject.otherproton transferen
dc.subject.otherelectrostatic potentialen
dc.subject.otherredox chemistryen
dc.subject.otherelectron transferen
dc.subject.otherinfrared spectroscopyen
dc.titleQuantification of Local Electric Field Changes at the Active Site of Cytochrome c Oxidase by Fourier Transform Infrared Spectroelectrochemical Titrationsen
dc.typeArticleen
dc.type.versionpublishedVersionen
dcterms.bibliographicCitation.articlenumber669452en
dcterms.bibliographicCitation.doi10.3389/fchem.2021.669452en
dcterms.bibliographicCitation.journaltitleFrontiers in Chemistryen
dcterms.bibliographicCitation.originalpublishernameFrontiersen
dcterms.bibliographicCitation.originalpublisherplaceLausanneen
dcterms.bibliographicCitation.volume9en
tub.accessrights.dnbfreeen
tub.affiliationFak. 2 Mathematik und Naturwissenschaften::Inst. Chemie::FG Modellierung biomolekularer Systemede
tub.affiliation.facultyFak. 2 Mathematik und Naturwissenschaftende
tub.affiliation.groupFG Modellierung biomolekularer Systemede
tub.affiliation.instituteInst. Chemiede
tub.publisher.universityorinstitutionTechnische Universität Berlinen

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