Biological electron transfers often occur between metal-containing cofactors that are separated by very large molecular distances. Employing photosensitizer-modified iron and copper proteins, we have shown that single-step electron tunneling can occur on nanosecond to microsecond timescales at distances between 15 and 20 Å. We also have shown that charge transport can occur over even longer distances by hole hopping (multistep tunneling) through intervening tyrosines and tryptophans. In this perspective, we advance the hypothesis that such hole hopping through Tyr/Trp chains could protect oxygenase, dioxygenase, and peroxidase enzymes from oxidative damage. In support of this view, by examining the structures of P450 (CYP102A) and 2OG-Fe (TauD) enzymes, we have identified candidate Tyr/Trp chains that could transfer holes from uncoupled high-potential intermediates to reductants in contact with protein surface sites.

中文翻译：

---

电子流过生物分子：空穴跳跃能保护蛋白质免受氧化损伤吗？

生物电子转移经常发生在由非常大的分子距离分开的含金属辅因子之间。使用光敏剂修饰的铁和铜蛋白，我们已经证明单步电子隧穿可以在 15 到 20 Å 的距离处以纳秒到微秒的时间尺度发生。我们还表明，通过中间的酪氨酸和色氨酸进行空穴跳跃（多步隧道），可以在更长的距离上发生电荷传输。从这个角度来看，我们提出了这样一个假设，即这种通过 Tyr/Trp 链的空穴跳跃可以保护加氧酶、双加氧酶和过氧化物酶免受氧化损伤。为了支持这一观点，通过检查 P450 (CYP102A) 和 2OG-Fe (TauD) 酶的结构，