High-Resolution Extended X-ray Absorption Fine Structure Analysis Provides Evidence for a Longer Fe···Fe Distance in the Q Intermediate of Methane Monooxygenase.
High-Resolution Extended X-ray Absorption Fine Structure Analysis Provides Evidence for a Longer Fe···Fe Distance in the Q Intermediate of Methane Monooxygenase.
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高分辨率扩展的X射线吸收精细结构分析为甲烷单加氧酶的Q中间体中较长的Fe···Fe距离提供了证据。
DOI：
10.1021/jacs.8b10313
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发表时间：
2018-12-05
影响因子：
15
通讯作者：
DeBeer S
中科院分区：
文献类型：
--
作者：
Cutsail GE 3rd;Banerjee R;Zhou A;Que L Jr;Lipscomb JD;DeBeer S
尽管经过数十年的深入研究，可溶性甲烷单加氧酶（sMMO）的甲烷C-H键断裂二铁（IV）中间体Q的核心结构仍然存在争议，相互矛盾的报道支持“钻石”二铁核心结构或开放核心结构。早期的EXAFS数据将短的2.46 μ Fe-Fe距离分配给Q（Shu等人，Science 1997），这与几个理论研究不一致，并且与我们最近的高分辨率Fe K边缘X射线吸收光谱（XAS）研究（Castillo等人，JACS，2017）。在这里，我们重新访问的EXAFS的Q使用高能量分辨率荧光检测扩展X射线吸收精细结构（HERFD-EXAFS）的研究。目前的数据显示，没有证据表明短的Fe-Fe距离，而是一个长的3.4 π diiron距离，如在开核合成模型复合物中观察到的。先前报道的2.46 μ m特征可能来自实验装置的背景金属铁贡献，由于选择性增加，该背景金属铁在HERFD EXAFS中被消除。在这里，我们已经探讨了起源的短diiron功能在部分荧光产额EXAFS测量和讨论的诊断功能的背景金属散射贡献的EXAFS稀释的生物样品。最后，在样品制备的差异和由此产生的样品不均匀性在快速冷冻淬火样品EXAFS分析进行了讨论。所提出的方法具有广泛的影响EXAFS研究的所有稀释含铁样品。
Despite decades of intense research, the core structure of the methane C-H bond breaking diiron(IV) intermediate, Q, of soluble methane monooxygenase (sMMO) remains controversial, with conflicting reports supporting either a ‘diamond’ diiron core structure or an open-core structure. Early EXAFS data assigned a short 2.46 Å Fe-Fe distance to Q (Shu, et al., Science 1997) that is inconsistent with several theoretical studies and in conflict with our recent high-resolution Fe K-edge X-ray absorption spectroscopy (XAS) studies (Castillo, et al., JACS, 2017). Herein, we revisit the EXAFS of Q using high-energy resolution fluorescence-detected extended X-ray absorption fine structure (HERFD-EXAFS) studies. The present data show no evidence for a short Fe-Fe distance, but rather a long 3.4 Å diiron distance, as observed in open-core synthetic model complexes. The previously reported 2.46 Å feature plausibly arises from a background metallic iron contribution from the experimental setup, which is eliminated in HERFD EXAFS due to the increased selectivity. Herein, we have explored the origin of the short diiron feature in partial-fluorescent yield EXAFS measurements and discuss the diagnostic features of background metallic scattering contribution to the EXAFS of dilute biological samples. Lastly, differences in sample preparation and resultant sample inhomogeneity in rapid-freeze quenched samples for EXAFS analysis are discussed. The presented approaches have broad implications for EXAFS studies of all dilute iron-containing samples.
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影响因子：
15
作者：
Castillo RG;Banerjee R;Allpress CJ;Rohde GT;Bill E;Que L Jr;Lipscomb JD;DeBeer S
通讯作者：
DeBeer S
甲烷酶氧化甲醇的酶促氧化中的关键物种的结构。
影响因子：
64.8
作者：
Banerjee, Rahul;Proshlyakov, Yegor;Lipscomb, John D.;Proshlyakov, Denis A.
通讯作者：
Proshlyakov, Denis A.
影响因子：
15
作者：
FOX, BG;HENDRICH, MP;MUNCK, E
通讯作者：
MUNCK, E
影响因子：
8.6
作者：
HAMALAINEN, K;SIDDONS, DP;BERMAN, LE
通讯作者：
BERMAN, LE
影响因子：
62.1
作者：
Jasniewski AJ;Que L Jr
通讯作者：
Que L Jr