Probing the Proton-Loading Site of Cytochrome C Oxidase Using Time-Resolved Fourier Transform Infrared Spectroscopy

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dc.contributor.author Gorbikova, Elena
dc.contributor.author Samsonov, Sergey A.
dc.contributor.author Kalendar, Ruslan
dc.date.accessioned 2020-08-07T13:37:24Z
dc.date.available 2020-08-07T13:37:24Z
dc.date.issued 2020-07-27
dc.identifier.citation Gorbikova, E.; Samsonov, S.A.; Kalendar, R. Probing the Proton-Loading Site of Cytochrome C Oxidase Using Time-Resolved Fourier Transform Infrared Spectroscopy. Molecules 2020, 25, 3393.
dc.identifier.uri http://hdl.handle.net/10138/318207
dc.description.abstract Crystal structure analyses at atomic resolution and FTIR spectroscopic studies of cytochrome <i>c</i> oxidase have yet not revealed protonation or deprotonation of key sites of proton transfer in a time-resolved mode. Here, a sensitive technique to detect protolytic transitions is employed. In this work, probing a proton-loading site of cytochrome <i>c</i> oxidase from Paracoccus denitrificans with time-resolved Fourier transform infrared spectroscopy is presented for the first time. For this purpose, variants with single-site mutations of N131V, D124N, and E278Q, the key residues in the D-channel, were studied. The reaction of mutated C<i>c</i>O enzymes with oxygen was monitored and analyzed. Seven infrared bands in the &ldquo;fast&rdquo; kinetic spectra were found based on the following three requirements: (1) they are present in the &ldquo;fast&rdquo; phases of N131V and D124N mutants, (2) they have reciprocal counterparts in the &ldquo;slow&rdquo; kinetic spectra in these mutants, and (3) they are absent in &ldquo;fast&rdquo; kinetic spectra of the E278Q mutant. Moreover, the double-difference spectra between the first two mutants and E278Q revealed more IR bands that may belong to the proton-loading site protolytic transitions. From these results, it is assumed that several polar residues and/or water molecule cluster(s) share a proton as a proton-loading site. This site can be propionate itself (holding only a fraction of H+), His403, and/or water cluster(s).
dc.language.iso en
dc.publisher Multidisciplinary Digital Publishing Institute
dc.title Probing the Proton-Loading Site of Cytochrome C Oxidase Using Time-Resolved Fourier Transform Infrared Spectroscopy en
dc.date.updated 2020-08-07T13:37:24Z
dc.type.uri http://purl.org/eprint/entityType/JournalArticle
dc.type.uri http://purl.org/eprint/entityType/Expression
dc.type.uri http://purl.org/eprint/entityType/Expression

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