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首页> 外文期刊>Chemistry: A European journal >Phototriggering electron flow through Re~I-modified pseudomonas aeruginosa azurins
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Phototriggering electron flow through Re~I-modified pseudomonas aeruginosa azurins

机译：通过Re〜I修饰的铜绿假单胞菌天青蛋白的光触发电子流

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摘要

The [Re~I(CO)_3(4,7-dimethyl-1,10-phenanthroline) (histidine-124)(tryptophan-122)] complex, denoted [Re~I(dmp)(W122)], of Pseudomonas aeruginosa azurin behaves as a single photoactive unit that triggers very fast electron transfer (ET) from a distant (2 nm) Cu~(I) center in the protein. Analysis of time-resolved (ps-μs) IR spectroscopic and kinetics data collected on [Re~I(dmp)(W122)AzM] (in which M=Zn II, Cu~(II), Cu~(I); Az=azurin) and position-122 tyrosine (Y), phenylalanine (F), and lysine (K) mutants, together with excited-state DFT/time-dependent (TD)DFT calculations and X-ray structural characterization, reveal the character, energetics, and dynamics of the relevant electronic states of the [Re~I(dmp)(W122)] unit and a cascade of photoinduced ET and relaxation steps in the corresponding Re-azurins. Optical population of [Re~I(imidazole-H124)(CO)_3] → dmp 1CT states (CT=charge transfer) is followed by around 110 fs intersystem crossing and about 600 ps structural relaxation to a ~3CT state. The IR spectrum indicates a mixed Re~I(CO)_3,A → dmp/π → π*(dmp) character for aromatic amino acids A122 (A=W, Y, F) and Re~I(CO)_3 → dmp metal-ligand charge transfer (MLCT) for [Re~I(dmp)(K122)AzCu~(II)]. In a few ns, the ~3CT state of [Re~I(dmp)(W122)AzM] establishes an equilibrium with the [Re~I(dmp.~-)(W122.~+)AzM] charge-separated state, ~3CS, whereas the ~3CT state of the other Y, F, and K122 proteins decays to the ground state. In addition to this main pathway, ~3CS is populated by fs- and ps-W(indole) → Re II ET from 1CT and the initially "hot" ~3CT states, respectively. The ~3CS state undergoes a tens-of-ns dmp.~- → W122.~+ ET recombination leading to the ground state or, in the case of the Cu~(I) azurin, a competitively fast (≈ 30 ns over 1.12 nm) Cu~(I) → W.+ ET, to give [Re~I(dmp.~-)(W122)AzCu~(II)]. The overall photoinduced Cu~(I) → Re(dmp) ET through [Re~I(dmp)(W122) AzCu~(I)] occurs over a 2 nm distance in <50 ns after excitation, with the intervening fast ~3CT-~3CS equilibrium being the principal accelerating factor. No reaction was observed for the three Y, F, and K122 analogues. Although the presence of [Re(dmp)(W122)AzCu~(II)] oligomers in solution was documented by mass spectrometry and phosphorescence anisotropy, the kinetics data do not indicate any significant interference from the intermolecular ET steps. The ground-state dmp-indole π-π interaction together with well-matched W/W.~+ and excited-state [Re II(CO)_3(dmp.~-)]/[Re~I(CO) _3(dmp.~-)] potentials that result in very rapid electron interchange and ~3CT-~3CS energetic proximity, are the main factors responsible for the unique ET behavior of [Re~I(dmp)(W122)]- containing azurins. Time to accelerate! IR spectroscopic and DFT/time-dependent (TD)DFT analysis reveals factors underlying the dramatic acceleration of long-range electron transfer (ET) in mutants of Pseudomonas aeruginosa azurin labeled with a [Re~I(CO)_3(α-diimine)] chromophore next to a tryptophan (see scheme). The Re-tryptophan pair operates as a single photoactive unit that triggers several ET pathways (ET1, ET2), in fs-ns timescales and efficient hole-injection into the peptide.
机译：假单胞菌的[Re〜I（CO）_3（4,7-二甲基-1,10-菲咯啉）（组氨酸-124）（色氨酸-122）]络合物，表示为[Re〜I（dmp）（W122）]铜绿假单胞菌的天青蛋白表现为一个单一的光敏单元，可触发蛋白质中距Cu（I）远的（2 nm）中心极快的电子转移（ET）。在[Re〜I（dmp）（W122）AzM]（其中M = Zn II，Cu〜（II），Cu〜（I）; Az上）上收集的时间分辨（ps-μs）红外光谱和动力学数据的分析= azurin）和122位酪氨酸（Y），苯丙氨酸（F）和赖氨酸（K）突变体，以及激发态DFT /时间依赖性（TD）DFT计算和X射线结构表征，揭示了该特征， [Re〜I（dmp）（W122）]单元的相关电子态的能量学和动力学，以及相应Re-azurins中一系列光诱导的ET和弛豫步骤。 [Re〜I（咪唑-H124）（CO）_3]→dmp 1CT态的光学填充（CT =电荷转移），随后发生约110 fs的系统间交叉和约600 ps的结构弛豫，直至〜3CT态。红外光谱表明芳香族氨基酸A122（A = W，Y，F）和Re〜I（CO）_3→dmp的混合Re〜I（CO）_3，A→dmp /π→π*（dmp）特征[Re〜I（dmp）（K122）AzCu〜（II）]的金属配体电荷转移（MLCT）。在数ns内，[Re〜I（dmp。（W122）AzM]]的〜3CT状态与[Re〜I（dmp。〜-）（W122。〜+）AzM]电荷分离状态建立平衡， 〜3CS，而其他Y，F和K122蛋白的〜3CT状态衰减为基态。除了该主要途径外，〜3CS分别由来自1CT和最初“热”〜3CT状态的fs-和ps-W（吲哚）→Re II ET组成。 〜3CS状态经历了几十ns dmp。〜-→W122。〜+ ET重组，导致基态，或者在Cu〜（I）天青蛋白的情况下，具有竞争性快（约1.12 ns约30 ns） nm）Cu〜（I）→W. + ET，得到[Re〜I（dmp。〜-）（W122）AzCu〜（II）]。通过[Re〜I（dmp）（W122）AzCu〜（I）]，整个光诱导的Cu〜（I）→Re（dmp）ET发生在激发后小于50 ns的2 nm距离内，中间快速〜3CT -〜3CS平衡是主要的加速因素。三种Y，F和K122类似物均未观察到反应。尽管通过质谱和磷光各向异性证明了[Re（dmp）（W122）AzCu〜（II）]低聚物的存在，但动力学数据并未表明分子间ET步骤有任何重大干扰。基态dmp-吲哚π-π相互作用以及匹配良好的W / W.〜+和激发态[Re II（CO）_3（dmp。〜-）] / [Re〜I（CO）_3（导致非常快速的电子交换和〜3CT-〜3CS高能接近的电势是导致[Re〜I（dmp）（W122）]-含金联蛋白独特ET行为的主要因素。时间加速！红外光谱和DFT /时间依赖性（TD）DFT分析揭示了标记有[Re〜I（CO）_3（α-diimine）的铜绿假单胞菌天青蛋白突变体中远距离电子转移（ET）急剧加速的潜在因素色氨酸旁边的发色团（请参阅方案）。 Re-色氨酸对作为单个光敏单元运行，以fs-ns时标触发有效的ET途径（ET1，ET2），并有效地将空穴注入肽中。

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