Department of Chemistry, University of Siena, Siena 53100, Italy.
Proteins. 2012 May;80(5):1476-83. doi: 10.1002/prot.24046. Epub 2012 Mar 2.
A catalytically active tryptophan radical has been demonstrated to be involved in the long-range electron transfer to the heme cofactor of lignin peroxidase (LiP) from Phanerochaete chrysosporium although no direct detection by EPR spectroscopy of the tryptophan radical intermediate has been reported to date. An engineering-based approach has been used to manipulate the microenvironment of the redox-active tryptophan site in LiP and Coprinus cinereus Peroxidase (CiP), allowing the direct evidence of the tryptophan radical species. In light of the newly available EPR experimental data, we performed a quantum mechanical/molecular mechanics computational study to characterize the tryptophan radicals in the above protein matrices as well as in pristine LiP. The nature of the tryptophan radicals is discussed together with the analysis of their environment with the aim of understanding the different behavior of pristine LiP in comparison with that of LiP and CiP variants.
虽然迄今为止尚未有报道通过 EPR 光谱直接检测到木质素过氧化物酶（LiP）中色氨酸自由基中间体，但已证明催化活性的色氨酸自由基参与了来自黄孢原毛平革菌的 LiP 向血红素辅基的长程电子转移。目前已经采用基于工程的方法来操纵 LiP 和云芝漆酶（CiP）中氧化还原活性色氨酸位点的微环境，从而可以直接证明色氨酸自由基物种的存在。鉴于新获得的 EPR 实验数据，我们进行了量子力学/分子力学计算研究，以在上述蛋白质基质以及原始 LiP 中对色氨酸自由基进行了特征描述。本文讨论了色氨酸自由基的性质，并分析了其所处的环境，旨在了解原始 LiP 与 LiP 和 CiP 变体相比的不同行为。
