TY - JOUR
T1 - Redox properties of thermus thermophilus ba3
T2 - Different electron-proton coupling in oxygen reductases?
AU - Sousa, Filipa L.
AU - Veríssimo, Andreia F.
AU - Baptista, António M.
AU - Soulimane, Tewfik
AU - Teixeira, Miguel
AU - Pereira, Manuela M.
PY - 2008/3/15
Y1 - 2008/3/15
N2 - A comprehensive study of the thermodynamic redox behavior of the hemes of the ba3 enzyme from Thermus thermophilus, a B-type heme-copper oxygen reductase, is presented. This enzyme, in contrast to those having a single type of heme, allows the B- and A-type hemes to be monitored separately by visible spectroscopy and the reduction potential of each heme to be determined unequivocally. The relative order of the midpoint reduction potentials of each center changed in the pH range from 6 to 8.4, and both hemes present a significant redox-Bohr effect. For instance, at pH 7, the midpoint reduction potentials of the hemes B and A3 are 213 mV and 285 mV, respectively, whereas at pH 8.4, the order is reversed: 246 mV for heme B and 199 mV for heme A3. The existence of redox anticooperativity was established by introducing a redox interaction parameter in a model of pairwise interacting redox centers.
AB - A comprehensive study of the thermodynamic redox behavior of the hemes of the ba3 enzyme from Thermus thermophilus, a B-type heme-copper oxygen reductase, is presented. This enzyme, in contrast to those having a single type of heme, allows the B- and A-type hemes to be monitored separately by visible spectroscopy and the reduction potential of each heme to be determined unequivocally. The relative order of the midpoint reduction potentials of each center changed in the pH range from 6 to 8.4, and both hemes present a significant redox-Bohr effect. For instance, at pH 7, the midpoint reduction potentials of the hemes B and A3 are 213 mV and 285 mV, respectively, whereas at pH 8.4, the order is reversed: 246 mV for heme B and 199 mV for heme A3. The existence of redox anticooperativity was established by introducing a redox interaction parameter in a model of pairwise interacting redox centers.
UR - http://www.scopus.com/inward/record.url?scp=44049088504&partnerID=8YFLogxK
U2 - 10.1529/biophysj.107.122614
DO - 10.1529/biophysj.107.122614
M3 - Article
C2 - 18065462
AN - SCOPUS:44049088504
SN - 0006-3495
VL - 94
SP - 2434
EP - 2441
JO - Biophysical Journal
JF - Biophysical Journal
IS - 6
ER -