The Low‐Spin ⇌ High‐Spin Transition of Camphor‐Bound Cytochrome P‐450
The Low‐Spin ⇌ High‐Spin Transition of Camphor‐Bound Cytochrome P‐450
复制标题
樟脑结合细胞色素 P-450 的低自旋 ⇌ 高自旋转变
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
P. Debey
中科院分区：
文献类型：
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作者：
R. Lange;C. Bonfils;P. Debey
樟脑结合的细胞色素P-450的自旋状态在很大程度上取决于水和混合有机缓冲液中的介质和温度。在零度以下的温度下，多环芳烃、离子强度或樟脑浓度的变化会使自旋平衡从几乎纯的高自旋形式改变为几乎纯的低自旋形式。由于跃迁的表观pKa是log I的线性函数，自旋态似乎是由血红素附近的静电势控制的。发现K+对自旋态有特殊的影响。
The spin state of camphor-bound cytochrome P-450 is shown to depend largely on medium and temperature in aqueous as well as in mixed organic buffer. At sub-zero temperatures a variation of paH, ionic strength or camphor concentration modifies the spin equilibrium from nearly pure high-spin form to nearly pure low-spin form. Since the apparent pKa of transition is a linear function of log I, the spin state seems to be controlled by the electrostatic potential in the heme proximity. K+ is found to have a specific effect on the spin state.
The change of enthalpy, ΔH values, of the spin transition depends on the same parameters as the equilibrium constant, in the organic cosolvent as well as in aqueous buffer. As the cosolvent effect is reflected by higher ΔH values, and KCI and pH tend to lower ΔH, the cosolvent effect can easily be compensated. Therefore kinetic studies of the spin conversion might well be undertaken at sub-zero temperature in this solvent.