TY - JOUR
T1 - Electron paramagnetic resonance and spectrophotometric studies of the peroxide compounds of manganese-substituted horseradish peroxidase, cytochrome-c peroxidase and manganese-porphyrin model complexes
AU - Hori, Hiroshi
AU - Ikeda-Saito, Masao
AU - Yonetani, Takashi
N1 - Funding Information:
tions and discussions. One of the authors (H.H.) also thanks Mr. T. Hotta of Osaka University, Japan, for his technical assistance. This investigation has been supported in part by research grants from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20014 (HL 14508 to T.Y. and AI 20463 to M.I.-S.) and from the National Science Foundation, Washington, DC (PCM 83-16935 to T.Y.).
PY - 1987/3/18
Y1 - 1987/3/18
N2 - Peroxide compounds of manganese protoporphyrin IX and its complexes with apo-horseradish peroxidase and apocytochrome-c peroxidase were characterized by electron absorption and electron paramagnetic resonance spectroscopies. An intermediate formed upon titration of Mn(III)-horseradish peroxidase with hydrogen peroxide exhibited a new electron paramagnetic resonance absorption at g = 5.23 with a definite six-lined 55Mn hyperfine (AMn = 8.2 mT). Neither a porphyrin π-cation radical nor any other radical in the apoprotein moiety could be observed. The reduced form of Mn-horseradish peroxidase, Mn(II)-horseradish peroxidase, reacted with a stoichiometric amount of hydrogen peroxide to form a peroxide compound whose electronic absorption spectrum was identical with that formed from Mn(III)-horseradish peroxidase. The electronic state of the peroxide compound of manganese horseradish peroxidase was thus concluded to be Mn(IV), S = 3 2. Mn(III)-cytochrome-c peroxidase reacted with stoichiometry quantities of hydrogen peroxide to form a catalytically active intermediate. The electronic absorption spectrum was very similar to that of a higher oxidation state of manganese porphyrin, Mn(V). Since the peroxide compound of manganese cytochrome-c peroxidase retained two oxidizing equivalents per mol of the enzyme (Yonetani, T. and Asakura, T. (1969) J. Biol. Chem. 244, 4580-4588), this peroxide compound might contain an Mn(V) center.
AB - Peroxide compounds of manganese protoporphyrin IX and its complexes with apo-horseradish peroxidase and apocytochrome-c peroxidase were characterized by electron absorption and electron paramagnetic resonance spectroscopies. An intermediate formed upon titration of Mn(III)-horseradish peroxidase with hydrogen peroxide exhibited a new electron paramagnetic resonance absorption at g = 5.23 with a definite six-lined 55Mn hyperfine (AMn = 8.2 mT). Neither a porphyrin π-cation radical nor any other radical in the apoprotein moiety could be observed. The reduced form of Mn-horseradish peroxidase, Mn(II)-horseradish peroxidase, reacted with a stoichiometric amount of hydrogen peroxide to form a peroxide compound whose electronic absorption spectrum was identical with that formed from Mn(III)-horseradish peroxidase. The electronic state of the peroxide compound of manganese horseradish peroxidase was thus concluded to be Mn(IV), S = 3 2. Mn(III)-cytochrome-c peroxidase reacted with stoichiometry quantities of hydrogen peroxide to form a catalytically active intermediate. The electronic absorption spectrum was very similar to that of a higher oxidation state of manganese porphyrin, Mn(V). Since the peroxide compound of manganese cytochrome-c peroxidase retained two oxidizing equivalents per mol of the enzyme (Yonetani, T. and Asakura, T. (1969) J. Biol. Chem. 244, 4580-4588), this peroxide compound might contain an Mn(V) center.
KW - ESR
KW - Manganese(IV)-porphyrin complex
KW - Peroxidase
KW - manganese-substituted
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U2 - 10.1016/0167-4838(87)90249-4
DO - 10.1016/0167-4838(87)90249-4
M3 - Article
C2 - 3030431
AN - SCOPUS:0023143477
VL - 912
SP - 74
EP - 81
JO - BBA - Protein Structure
JF - BBA - Protein Structure
SN - 1570-9639
IS - 1
ER -