Fourier-transform infrared study of azide binding to the Fea3-CuB binuclear site of bovine heart cytochrome c oxidase: new evidence for a redox-linked conformational change at the binuclear site

Biochemistry ◽  
1993 ◽  
Vol 32 (1) ◽  
pp. 174-182 ◽  
Author(s):  
Motonari Tsubaki ◽  
Shinya Yoshikawa
Keyword(s):  
Fourier Transform ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Conformational Change ◽  
Fourier Transform Infrared ◽  
Infrared Study ◽  
Bovine Heart ◽  
New Evidence ◽  
Azide Binding

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

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3393
Author(s):  
Elena Gorbikova ◽  
Sergey A. Samsonov ◽  
Ruslan Kalendar
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Fourier Transform Infrared Spectroscopy ◽  
Paracoccus Denitrificans ◽  
Fourier Transform Infrared ◽  
Double Difference ◽  
Time Resolved ◽  
Fast Kinetic

Crystal structure analyses at atomic resolution and FTIR spectroscopic studies of cytochrome c 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 c 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 CcO enzymes with oxygen was monitored and analyzed. Seven infrared bands in the “fast” kinetic spectra were found based on the following three requirements: (1) they are present in the “fast” phases of N131V and D124N mutants, (2) they have reciprocal counterparts in the “slow” kinetic spectra in these mutants, and (3) they are absent in “fast” 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).

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