TY  - JOUR
A1  - Kannt, Aimo
A1  - Pfitzner, Ute
A1  - Ruitenberg, Maarten
A1  - Hellwig, Petra
A1  - Ludwig, Bernd
A1  - Mäntele, Werner
A1  - Fendler, Klaus
A1  - Michel, Hartmut
T1  - Mutation of Arg-54 strongly influences heme composition and rate and directionality of electron transfer in Paracoccus denitrificans cytochrome c oxidase
T2  - Journal of biological chemistry
N2  - The effect of a single site mutation of Arg-54 to methionine in Paracoccus denitrificans cytochrome c oxidase was studied using a combination of optical spectroscopy, electrochemical and rapid kinetics techniques, and time-resolved measurements of electrical membrane potential. The mutation resulted in a blue-shift of the heme a alpha-band by 15 nm and partial occupation of the low-spin heme site by heme O. Additionally, there was a marked decrease in the midpoint potential of the low-spin heme, resulting in slow reduction of this heme species. A stopped-flow investigation of the reaction with ferrocytochrome c yielded a kinetic difference spectrum resembling that of heme a(3). This observation, and the absence of transient absorbance changes at the corresponding wavelength of the low-spin heme, suggests that, in the mutant enzyme, electron transfer from Cu(A) to the binuclear center may not occur via heme a but that instead direct electron transfer to the high-spin heme is the dominating process. This was supported by charge translocation measurements where Deltapsi generation was completely inhibited in the presence of KCN. Our results thus provide an example for how the interplay between protein and cofactors can modulate the functional properties of the enzyme complex.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/75868
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-758680
SN  - 0021-9258
VL  - 274.1999
IS  - 53
SP  - 37974
EP  - 37981
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -