TY - JOUR
T1 - Time-resolved single-turnover of caa3 oxidase from Thermus thermophilus. Fifth electron of the fully reduced enzyme converts OH into EH state
AU - Siletsky, Sergey A.
AU - Belevich, Ilya
AU - Belevich, Nikolai P.
AU - Soulimane, Tewfik
AU - Verkhovsky, Michael I.
N1 - 2011 Elsevier B.V. All rights reserved.
PY - 2011/9
Y1 - 2011/9
N2 - The oxidative part of the catalytic cycle of the caa3-type cytochrome c oxidase from Thermus thermophilus was followed by time-resolved optical spectroscopy. Rate constants, chemical nature and the spectral properties of the catalytic cycle intermediates (Compounds A, P, F) reproduce generally the features typical for the aa3-type oxidases with some distinctive peculiarities caused by the presence of an additional 5-th redox-center-a heme center of the covalently bound cytochrome c. Compound A was formed with significantly smaller yield compared to aa3 oxidases in general and to ba3 oxidase from the same organism. Two electrons, equilibrated between three input redox-centers: heme a, CuA and heme c are transferred in a single transition to the binuclear center during reduction of the compound F, converting the binuclear center through the highly reactive OH state into the final product of the reaction-E H (one-electron reduced) state of the catalytic site. In contrast to previous works on the caa3-type enzymes, we concluded that the finally produced EH state of caa3 oxidase is characterized by the localization of the fifth electron in the binuclear center, similar to the OH → EH transition of the aa3-type oxidases. So, the fully-reduced caa3 oxidase is competent in rapid electron transfer from the input redox-centers into the catalytic heme-copper site.
AB - The oxidative part of the catalytic cycle of the caa3-type cytochrome c oxidase from Thermus thermophilus was followed by time-resolved optical spectroscopy. Rate constants, chemical nature and the spectral properties of the catalytic cycle intermediates (Compounds A, P, F) reproduce generally the features typical for the aa3-type oxidases with some distinctive peculiarities caused by the presence of an additional 5-th redox-center-a heme center of the covalently bound cytochrome c. Compound A was formed with significantly smaller yield compared to aa3 oxidases in general and to ba3 oxidase from the same organism. Two electrons, equilibrated between three input redox-centers: heme a, CuA and heme c are transferred in a single transition to the binuclear center during reduction of the compound F, converting the binuclear center through the highly reactive OH state into the final product of the reaction-E H (one-electron reduced) state of the catalytic site. In contrast to previous works on the caa3-type enzymes, we concluded that the finally produced EH state of caa3 oxidase is characterized by the localization of the fifth electron in the binuclear center, similar to the OH → EH transition of the aa3-type oxidases. So, the fully-reduced caa3 oxidase is competent in rapid electron transfer from the input redox-centers into the catalytic heme-copper site.
KW - Catalytic cycle intermediates
KW - Cytochrome c oxidase
KW - Electron transfer
KW - Thermus thermophilus
UR - http://www.scopus.com/inward/record.url?scp=80955180551&partnerID=8YFLogxK
U2 - 10.1016/j.bbabio.2011.05.006
DO - 10.1016/j.bbabio.2011.05.006
M3 - Article
C2 - 21609712
AN - SCOPUS:80955180551
SN - 0005-2728
VL - 1807
SP - 1162
EP - 1169
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 9
ER -