Structural model studies for the high-valent intermediate Q of methane monooxygenase from broken-symmetry density functional calculations
Structural model studies for the high-valent intermediate Q of methane monooxygenase from broken-symmetry density functional calculations
复制标题
DOI：
10.1016/j.ica.2007.06.007
复制
发表时间：
2008-03-03
影响因子：
2.8
通讯作者：
Noodleman, Louis
中科院分区：
文献类型：
--
作者：
Han, Wen-Ge;Noodleman, Louis
通过对Fe ~（2+）、Fe ~（2.5+）和Fe ~（2.5+）、Fe ~（3+）、Fe ~（3.5+）、Fe ~（4+）配合物的穆斯堡尔同质异能移测量值与电子密度的线性回归，得到了密度泛函理论（DFT）OPBE和OLYP泛函的穆斯堡尔同质异能移参数。从OPBE和OLYP泛函计算的样品Fe络合物的异构体位移和四极分裂与PW 91计算的那些类似[J. COMPUT. 27（2006）1292]，然而，PW 91与OPBE、OLYP线性回归的t参数不同。采用密度泛函OPBE、OLYP和PW 91，结合对称性破缺方法和类导体屏蔽（COSMO）溶剂化模型，研究了可溶性甲烷单加氧酶（MMOH）羟化酶组分中间体Q活性中心结构的四种模型.计算的性质，包括优化的几何结构，电子能量，pK（a）的，Fe净自旋布居，穆斯堡尔异构体位移和四极分裂，已被报道，并与现有的实验值进行比较。OPBE和OLYP方法对所有的活性位模型都正确地预测了高自旋反铁磁（AF）耦合的Fe 4+位. PW 91势高估了某些模型的Fe -配体共价性，因为自旋交叉。我们的计算和数据分析支持由Friesner和Lippard小组[J. Am. 123（2001）3836 - 3837]，其含有Fe 4+（μ- O）（2）Fe 4+中心、一个也与Glu 243和Glu 114的两个侧链氢键合的轴向水和一个来自Glu 144侧链的二齿羧酸酯基团，其可能代表MMOH-Q的活性位点。一种新的模型结构（图9所示的模型IV），其具有末端羟基和质子化的His 147，该His 147与附近的Fe解离，在其Fe（μ-O）（2）Fe金刚石核中更不对称，并且是中间体Q的另一个非常好的候选者。(c)2007年爱思唯尔B。V.保留所有权利。
Mossbauer isomer shift parameters have been obtained for both density functional theory ( DFT) OPBE and OLYP functionals by linear regressions between the measured isomer shifts and calculated electron densities at Fe nuclei for a number of Fe-2+,Fe- 2.5+ and Fe-2.5+,Fe- 3+,Fe- 3.5+,Fe- 4+ complexes grouped separately. The calculated isomer shifts and quadrupole splittings on the sample Fe complexes from OPBE and OLYP functionals are similar to those of PW91 calculations [ J. Comput. Chem. 27 ( 2006) 1292], however the. t parameters from the linear regressions differ between PW91 and OPBE, OLYP. Four models for the active site structure of intermediate Q of the hydroxylase component of soluble methane monooxygenase ( MMOH) have been studied, using three DFT functionals OPBE, OLYP, and PW91, incorporated with broken-symmetry methodology and the conductor-like screening ( COSMO) solvation model. The calculated properties, including optimized geometries, electronic energies, pK(a)'s, Fe net spin populations, and Mossbauer isomer shifts and quadrupole splittings, have been reported and compared with available experimental values. The high-spin antiferromagnetically ( AF) coupled Fe 4+ sites are correctly predicted by OPBE and OLYP methods for all active site models. PW91 potential overestimates the Fe - ligand covalencies for some of the models because of spin crossover. Our calculations and data analysis support the structure ( our current model II shown in Fig. 8) proposed by Friesner and Lippard's group [ J. Am. Chem. Soc. 123 ( 2001) 3836 - 3837], which contains an Fe4+( mu- O)(2)Fe4+ center, one axial water which also H- bonds to both side chains of Glu243 and Glu114, and one bidentate carboxylate group from the side chain of Glu144, which is likely to represent the active site of MMOH-Q. A new model structure ( model IV shown in Fig. 9), which has a terminal hydroxo and a protonated His147 which is dissociated from a nearby Fe, is more asymmetric in its Fe( mu-O)(2) Fe diamond core, and is another very good candidate for intermediate Q. (c) 2007 Elsevier B. V. All rights reserved.