Effect of protein dynamics on biological electron transfer
Effect of protein dynamics on biological electron transfer
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DOI：
10.1073/pnas.94.8.3703
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发表时间：
1997-04-15
影响因子：
11.1
通讯作者：
Stuchebrukhov, AA
中科院分区：
文献类型：
--
作者：
Daizadeh, I;Medvedev, ES;Stuchebrukhov, AA
对Ru修饰的（His 126）天青蛋白分子进行了蛋白质动力学对蛋白质基质介导的长距离隧道效应的计算机模拟。我们发现，隧道矩阵元素是一个敏感的功能的原子配置的部分蛋白质矩阵中的隧道电流（途径）本地化。分子动力学模拟表明，波动的矩阵元素可以发生在一个时间尺度短至10 fs。这些短时间的波动是一个强烈的动态耦合的隧穿电子的蛋白质核坐标的振动运动的指示。后者的结果在一个修改的传统马库斯图片的电子转移蛋白质。修正理论中的新元素是隧穿电子能够从介质中发射或吸收振动能量（声子）。因此，一些生物反应可能以无激活的方式发生。本文提出了一个能解释长距离电子转移反应中介质热涨落的解析理论模型。该模型表明，在长距离，声子修改的非弹性隧穿总是占主导地位的传统的弹性隧穿。
Computer simulations of the effect of protein dynamics on the long distance tunneling mediated by the protein matrix have been carried out for a Ru-modified (His 126) azurin molecule. We find that the tunneling matrix element is a sensitive function of the atomic configuration of the part of the protein matrix in which tunneling currents (pathways) are localized. Molecular dynamics simulations show that fluctuations of the matrix element can occur on a time scale as short as 10 fs. These short time fluctuations are an indication of a strong dynamic coupling of a tunneling electron to vibrational motions of the protein nuclear coordinates. The latter results in a modification of the conventional Marcus picture of electron transfer in proteins. The new element in the modified theory is that the tunneling electron is capable of emitting or absorbing vibrational energy (phonons) from the medium. As a result, some biological reactions may occur in an activationless fashion. An analytical theoretical model is proposed to account for thermal fluctuations of the medium in long distance electron transfer reactions. The model shows that, at long distances, the phonon-modified inelastic tunneling always dominates over the conventional elastic tunneling.