The potential span of photoredox reactions of porphyrins and chlorophyll at the lipid bilayer-water interface.
The potential span of photoredox reactions of porphyrins and chlorophyll at the lipid bilayer-water interface.
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脂质双层-水界面处卟啉和叶绿素的光氧化还原反应的电位跨度。
DOI：
10.1016/s0006-3495(81)84775-3
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发表时间：
1981
影响因子：
3.4
通讯作者：
Mauzerall,D
中科院分区：
文献类型：
--
作者：
Ilani,A;Mauzerall,D
用波长为590 mm的染料激光脉冲(半高0.3微秒)照射含有叶绿素(Chl)或八乙基卟啉镁(MgOEP)的脂双层和含有不同数量不同受体的分离溶液。在电压钳位电路中，在第一电流峰值处测量界面电荷转移。描述由不同受主转移的电荷的双曲饱和的常数仅与受主的氧化还原电势弱相关。在接受电子方面，一个不对称的分子，即2，6-苯二磺酸，是对称的2，6-二磺酸的20多倍。与这种可变的有效性相反，作为受主氧化还原电位的函数，转移的最大电荷量在截止值之前是恒定的：对于MgOEP，为-0.6V(对标准氢电极)，对于Chl，为-0.5V。通过跟踪光活性的下降和跨膜电位作为水氧化还原电位的函数，确定了双层膜中镁氧磷的可逆氧化还原电位。MgOEP为+0.77V，CHL约为0.7V(受稳定性限制)。由此，由MgOEP的三重态激发态的1.8 eV(内能)得到了1.4V的可逆氧化还原电势(自由能)。
Lipid bilayers containing chlorophyll (Chl) or magnesium octaethylporphyrin (MgOEP) and separating solutions containing varying amounts of differing acceptors are illuminated by a dye laser pulse (FWHM 0.3 microseconds) at 590 mm. Interfacial charge transfer is measured at the first current peak in a voltage clamp circuit. The constants describing the hyperbolic saturations of the charge transferred by differing acceptors are only weakly related to the redox potential of the acceptors. An assymetric molecule, anthraquinone-2-sulfonate, is over 20 times as effective in accepting the electron as is the symmetrical anthraquinone-2,6-disulfonate. In contrast to this variable effectiveness, the maximum amount of charge transferred as a function of acceptor redox potential is constant up to a cut-off value: -0.6 V (vs. standard hydrogen electrode) for MgOEP and -0.5 V for Chl. The reversible redox potential of MgOEP in the bilayer was determined by following both the decrease in photoactivity and the transmembrane potential as a function of aqueous redox potential. It is +0.77 V for MgOEP and approximately 0.7 V for Chl (limited by stability). Thus, a total of 1.4 V of reversible redox potential (free energy) is obtained from 1.8 eV (internal energy) of the triplet excited state of MgOEP.