TY - JOUR
T1 - Role of Thiolate Ligand in Spin State and Redox Switching in the Cytochrome P450 Catalytic Cycle
AU - Suzuki, Hiroshi
AU - Inabe, Kanako
AU - Shirakawa, Yoshinori
AU - Umezawa, Naoki
AU - Kato, Nobuki
AU - Higuchi, Tsunehiko
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/4/17
Y1 - 2017/4/17
N2 - The catalytic cycle of cytochrome P450 involves a change from the resting-state, water-bound, six-coordinated form (1, low-spin state) to a five-coordinated form (2, high-spin state) upon binding of a hydrophobic substrate. Here, we used a heme-thiolate model complex (SR complex) with THF as a model of nonionic H2O to address the question of whether or not coordination of nonionic water is sufficient to induce the low-spin state. Measurements of electronic absorption spectra and magnetic properties confirmed that five-coordinated SR complex has a high-spin state, and THF-bound, six-coordinated SR has a low-spin state in dichloromethane at ambient temperature. The redox potential E1/2 (FeII/FeIII) of THF-bound SR was 80-90 mV more negative than that of five-coordinated SR. These properties indicate SR is a good model of P450. Our results suggest that thiolate coordination plays a key role in setting the low energy barrier between the high-spin and low-spin states.
AB - The catalytic cycle of cytochrome P450 involves a change from the resting-state, water-bound, six-coordinated form (1, low-spin state) to a five-coordinated form (2, high-spin state) upon binding of a hydrophobic substrate. Here, we used a heme-thiolate model complex (SR complex) with THF as a model of nonionic H2O to address the question of whether or not coordination of nonionic water is sufficient to induce the low-spin state. Measurements of electronic absorption spectra and magnetic properties confirmed that five-coordinated SR complex has a high-spin state, and THF-bound, six-coordinated SR has a low-spin state in dichloromethane at ambient temperature. The redox potential E1/2 (FeII/FeIII) of THF-bound SR was 80-90 mV more negative than that of five-coordinated SR. These properties indicate SR is a good model of P450. Our results suggest that thiolate coordination plays a key role in setting the low energy barrier between the high-spin and low-spin states.
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U2 - 10.1021/acs.inorgchem.6b02499
DO - 10.1021/acs.inorgchem.6b02499
M3 - Article
C2 - 28350457
AN - SCOPUS:85018477464
VL - 56
SP - 4245
EP - 4248
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 8
ER -