Gray Harry B, Winkler Jay R
Beckman Institute, California Institute of Technology, Pasadena, California 91125.
Chem Phys Lett. 2009 Nov 24;483(1-3):1-9. doi: 10.1016/j.cplett.2009.10.051.
Electron transfers in photosynthesis and respiration commonly occur between metal-containing cofactors that are separated by large molecular distances. Employing laser flash-quench triggering methods, we have shown that 20-Å, coupling-limited Fe(II) to Ru(III) and Cu(I) to Ru(III) electron tunneling in Ru-modified cytochromes and blue copper proteins can occur on the microsecond timescale both in solutions and crystals. Redox equivalents can be transferred even longer distances by multistep tunneling, often called hopping, through intervening amino acid side chains. Our work has established that 20-Å hole hopping through an intervening tryptophan is two orders of magnitude faster than single-step electron tunneling in a Re-modified blue copper protein.
光合作用和呼吸作用中的电子转移通常发生在含金属的辅因子之间，这些辅因子在分子层面上相隔很远的距离。利用激光闪光淬灭触发方法，我们已经证明，在钌修饰的细胞色素和蓝铜蛋白中，20埃（Å）的、受耦合限制的从亚铁（Fe(II)）到钌（III）以及从亚铜（Cu(I)）到钌（III）的电子隧穿，在溶液和晶体中都能在微秒时间尺度上发生。氧化还原当量可以通过多步隧穿（通常称为跳跃），穿过中间的氨基酸侧链，转移更长的距离。我们的研究已经证实，通过中间色氨酸进行的20埃空穴跳跃比铼修饰的蓝铜蛋白中的单步电子隧穿快两个数量级。
