PH-DEPENDENT FORMS OF THE FERRYL HEME IN MYOGLOBIN PEROXIDE ANALYZED BY VARIABLE-TEMPERATURE MAGNETIC CIRCULAR-DICHROISM
PH-DEPENDENT FORMS OF THE FERRYL HEME IN MYOGLOBIN PEROXIDE ANALYZED BY VARIABLE-TEMPERATURE MAGNETIC CIRCULAR-DICHROISM
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DOI：
10.1042/bj2610515
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发表时间：
1989-07-15
影响因子：
4.1
通讯作者：
THOMSON, AJ
中科院分区：
文献类型：
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作者：
FOOTE, N;GADSBY, PMA;THOMSON, AJ
肌红蛋白与H_2O_2的反应产物根据外界pH的不同，以两种不同的形式存在。变温磁圆二向色性(m.c.d.)光谱分析表明，两者都含有氧合离子Fe(IV)=O。碱性肌红蛋白过氧化氢常被用作含血红素过氧化物酶催化循环中氧化中间体的模型，但吸附和m.c.d。光谱表明，酸性形式与辣根过氧化物酶化合物II等物种密切相关。这种差异初步归因于碱性肌红蛋白过氧化氢中近端组氨酸配体的电离。还表明，m.c.d.方法允许估计两种形式的零场分裂参数，对于碱性形式和酸性形式分别得到D=28.0±-0.3 cm-1和35.0±-0.5 cm-1。
The reaction product of myoglobin and H2O2 exists in two different forms according to the external pH. Varied-temperature magnetic-circular dichroism (m.c.d.) spectroscopy demonstrates that both contain the oxygerryl ion Fe(IV)=O. Alkaline myoglobin peroxide has often been used as a model for oxidized intermediates in the catalytic cycles of haem-containing peroxidases, but absorption and m.c.d. spectra show that the acid form is much closely related to species such as horseradish peroxidase Compound II. The differences are tentatively ascribed to ionization of the proximal histidine ligand in alkaline myoglobin peroxide. It is also shown that the m.c.d. method allows an estimate of the zero-field splitting parameter of both forms, values of D = 28.0.+-.3 cm-1 and 35.0.+-.5 cm-1 being obtained for the alkaline and acid forms respectively.