Theoretical analyses of the fluorescence lifetimes of the D-amino acid oxidase–benzoatecomplex dimer from porcine kidney: Molecular dynamics simulation and photoinduced electron transfer
Theoretical analyses of the fluorescence lifetimes of the D-amino acid oxidase–benzoatecomplex dimer from porcine kidney: Molecular dynamics simulation and photoinduced electron transfer
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猪肾D-氨基酸氧化酶-苯甲酸复合物二聚体荧光寿命的理论分析：分子动力学模拟和光诱导电子转移
DOI：
10.1039/c4ra05211k
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发表时间：
2014
期刊：
影响因子：
3.9
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
采用分子动力学模拟（MDS）和电子转移理论研究了猪肾D-氨基酸氧化酶-苯甲酸盐复合物（DAOB）二聚体中苯甲酸盐（Bz）和芳香族氨基酸向异咯嗪（Iso*）的光诱导电子转移（ET）机理，并与DAOB单体中的情况进行了比较.如所报道的，DAOB二聚体显示0.85ps和4.8ps的两个荧光寿命分量。确定了Kakitani和Mataga（KM）模型中包含的ET参数，以便用MDS原子坐标再现这些寿命。Bz-异咯嗪（Iso）在亚基A（Sub A）中的距离为0.66 nm，在亚基B（Sub B）中的距离为0.68 nm，在单体中的距离为0.61 nm。发现4.8 ps和0.85 ps的荧光寿命分别来自Sub A和Sub B。在Sub A中，Tyr 228是最快的ET供体，其次是Bz和Tyr 55，而在Sub B中，Bz其次是Tyr 228和Tyr 314。Bz的ET速率在Sub B中最快，其次是Sub A和DAOB单体。在Iso附近获得的静态介电常数在DAOB二聚体和单体中为2.4-2.6，在全D-氨基氧化酶（DAAO）中为5.8-5.9。不同的介电常数可以解释DAOB（524 nm）和DAAO（530 nm）观察到的实验荧光峰。DAOB二聚体和单体Sub A和Sub B的ET速率对数与以中心距（Rc）和边距（Re）表示的给体-受体距离呈线性关系，表明传统的达顿规则在DAOB的ET过程中成立。将对数ET速率分解为电子耦合（EC）、平方根（SQ）和指数（GTRAM）项。结果发现，EC项和GTRAM项也随Rc线性减小。EC和GTRAM与Rc图中的斜率之和与对数ET速率与Rc函数中的斜率一致，表明GTRAM项对对数ET速率与Rc之间的线性关系做出了显著贡献。
The mechanism of photoinduced electron transfer (ET) from benzoate (Bz) and aromatic amino acids to the excited isoalloxazine (Iso*) in the D-amino acid oxidase–benzoate complex (DAOB) dimer from porcine kidney was studied using molecular dynamics simulation (MDS) and an electron transfer theory, and compared with that in the DAOB monomer. The DAOB dimer displayed two fluorescent lifetime components of 0.85 ps and 4.8 ps, as reported. The ET parameters contained in the Kakitani and Mataga (KM) model were determined so as to reproduce these lifetimes with MDS atomic coordinates. The Bz–isoalloxazine (Iso) distances were 0.66 nm in subunit A (Sub A), 0.68 nm in subunit B (Sub B) and 0.61 nm in the monomer. The fluorescent lifetimes of 4.8 ps and 0.85 ps were found to originate from Sub A and Sub B, respectively. In Sub A, Tyr228 was the fastest ET donor followed by Bz and Tyr55, while Bz was followed by Tyr228 and Tyr314 in Sub B. The ET rate from Bz was fastest in Sub B, followed by that in Sub A and the DAOB monomer. The static dielectric constants obtained near Iso were 2.4–2.6 in the DAOB dimer and monomer and 5.8–5.9 in holo D-amino oxidase (DAAO). The different dielectric constants could account for the experimental fluorescence peak observed for DAOB (524 nm) and DAAO (530 nm). Logarithmic ET rates decreased linearly with the donor–acceptor distance expressed by both center to center distance (Rc) and edge to edge distance (Re) in Sub A and Sub B of DAOB dimer and monomer, which reveals that the conventional Dutton rule holds in the ET processes in DAOB. The logarithmic ET rates were decomposed into the electronic coupling (EC), square root (SQ) and exponential (GTRAM) terms. It was found that both the EC term and the GTRAM term also decreased linearly with Rc. The sum of the slopes in the EC and GTRAM vs. Rc plots coincided with the slopes in the logarithmic ET rate vs. Rc functions, suggesting that the GTRAM term makes a significant contribution to the linear relations between logarithmic ET rate and Rc.