化学
反应性(心理学)
星团(航天器)
酶
氧化态
格式化
电子结构
立体化学
结晶学
光化学
计算化学
催化作用
生物化学
病理
程序设计语言
替代医学
医学
计算机科学
作者
Jianqiang Feng,Bin-ju Wang
标识
DOI:10.1063/1674-0068/cjcp2108134
摘要
[4Fe-4S]-dependent radical S-adenosylmethionine (SAM) proteins are a superfamily of oxidoreductases that can catalyze a series of challenging transformations using the common 5-dAdo radical intermediate. Although the structures and functions of radical SAM enzymes have been extensively studied, the electronic state-dependent reactions of the [4Fe-4S] clusters in these enzymes are still elusive. Herein we performed QM/MM calculations to elucidate the electronic state-dependent reactivity of the [4Fe-4S] cluster in pyruvate-formate lyase activating enzyme. Our calculations show that the electronic state-dependent SAM activation by the [4Fe-4S] clusters in radical SAM enzyme is determined by both the super-exchange and exchange-enhanced reactivities. The super-exchange coupling in the [4Fe-4S] cluster favors the antiferromagnetic coupling between two neighbouring pairs, which results in the α-electron rather than the β-electron donation from the [4Fe-4S]1+ cluster toward the SAM activation. Meanwhile, in the most favorable electronic state for the reductive cleavage of S-C5′, Fe4 would donate its α-electron to gain the maximum exchange interactions in the Fe4-block. Such super-exchange and exchange-enhanced reactivity could be the general principles for reactivities of [4Fe-4S] cluster in RS enzymes.
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