LOW-SPIN REVERSIBLE HIGH-SPIN TRANSITION OF CAMPHOR-BOUND CYTOCHROME-P-450 - EFFECTS OF MEDIUM AND TEMPERATURE ON EQUILIBRIUM DATA
LOW-SPIN REVERSIBLE HIGH-SPIN TRANSITION OF CAMPHOR-BOUND CYTOCHROME-P-450 - EFFECTS OF MEDIUM AND TEMPERATURE ON EQUILIBRIUM DATA
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DOI：
10.1111/j.1432-1033.1977.tb11847.x
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
DEBEY, P
中科院分区：
文献类型：
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作者：
LANGE, R;BONFILS, C;DEBEY, P
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介质和温度，在水溶液中以及在混合有机缓冲液中。在零度以下的温度下，paH、离子强度或樟脑浓度的变化将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。由于表观pKaof过渡是logI的线性函数，自旋状态似乎是由静电势在血红素附近控制。发现K+对自旋态有特殊的影响，在有机共溶剂和缓冲溶液中，自旋跃迁的焓变Δ H值取决于与平衡常数相同的参数.由于共溶剂效应反映在较高的Δ H值上，而KCl和pH值有降低ΔH的趋势，因此共溶剂效应很容易得到补偿。因此，自旋转换的动力学研究可以在零度以下的温度下在这种溶剂中进行。
The spin state of camphor‐bound cytochromeP‐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 pKaof transition is a linear function of logI, 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, ΔHvalues, 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 ΔHvalues, 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.