Comparative Study on the Mechanism of Photoinduced Electron Transfer from Tryptophan 168 to Excited Flavin in T169S and Wild-type Pyranose 2‐Oxidase
Comparative Study on the Mechanism of Photoinduced Electron Transfer from Tryptophan 168 to Excited Flavin in T169S and Wild-type Pyranose 2‐Oxidase
复制标题
T169S 和野生型吡喃糖 2-氧化酶中色氨酸 168 光诱导电子转移到激发黄素机制的比较研究
DOI：
10.1021/acsomega.8b02158
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发表时间：
2019
期刊：
影响因子：
4.1
通讯作者：
Haik Chosrowjan
中科院分区：
文献类型：
--
作者：
Arthit Nueangaudom;Kiattisak Lugsanangarm;Somsak Pianwanit;Sirirat Kokpol;Nadtanet Nunthaboot;Fumio Tanaka;Seiji Taniguchi;Haik Chosrowjan
用电子转移理论研究了T169S突变的吡喃糖2-氧化酶(P2O)中Trp168与异四氧嘧啶(Iso*)的光诱导电子转移(ET)速率，并将分子动力学模拟计算的结构性质与已报道的荧光寿命进行了拟合。将获得的ET率和相关物理量与报道的野生型(WT)P2O进行了比较。在T169S中，Iso的实验荧光寿命有两个分量：92-240 ps(取决于发射波长)和15 ps(与发射波长无关)。四个T169S亚基中的一个亚基(亚基C)显示低速率，其他三个亚基(亚基A、B和D)显示高速率。快成分的平均ET速率在480 nm约为10ps-1，在500 nm约为7ps-1，在530、555和580 nm约为4.2ps-1，低于WT P2O中报道的约17ps-1(480 Nm)、14ps-1(500 Nm)、9ps-1(530和555 nm)和11ps-1(580 Nm)，而T169S的慢成分速率(0.068 ps-1)高于WT的报道(0.00296 ps-1)。T169S的快组分比WT的ET率低是由于T169S的电子耦合项比WT的低，而T169S的慢组分的ET率比WT高是由于T169S的光产物与反应物之间的标准电子自由能差较小。T169S和WT P2O中的极不均匀电子转移速率也可以用标准的电子自由能隙项来解释。
The rates of photoinduced electron transfer (ET) from Trp168 to the excited isoalloxazine (Iso*) in the pyranose 2-oxidase (P2O) with T169S mutation were studied using ET theory by fitting structural properties calculated from molecular dynamics simulation to the reported fluorescence lifetimes. The obtained ET rates and related physical quantities were compared to those reported for the wild-type (WT) P2O. Experimental fluorescence lifetimes of Iso in T169S have two components of 92–240 fs (depending on the emission wavelength) and 15 ps (independent of the emission wavelength). One of the four T169S subunits (Sub C) displayed a low rate, and the other three (Sub A, B, and D) had high rates. Mean ET rates of the fast components were ca. 10 ps–1at 480 nm, 7 ps–1at 500 nm, and 4.2 ps–1at 530, 555, and 580 nm, which were lower than the reported rates in the WT P2O of ca. 17 ps–1at 480 nm, 14 ps–1at 500 nm, 9 ps–1at 530 and 555 nm, and 11 ps–1at 580 nm, while the rate for the slow component in T169S (0.068 ps–1) was higher than that reported in the WT (0.00296 ps–1). The lower ET rates in the fast components of T169S compared to those in the WT was due to the lower electron coupling term in T169S than in the WT, while the higher ET rate in the slow component of T169S compared to the WT was ascribed to a lower standard electronic free-energy gap between the photoproducts and reactants in T169S. The extremely heterogeneous ET rates in the both T169S and WT P2O were also explained by the standard electronic free-energy gap terms.