English  |  正體中文  |  简体中文  |  全文筆數/總筆數 : 6507/11669
造訪人次 : 29733569      線上人數 : 445
RC Version 3.2 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜尋範圍 進階搜尋

請使用永久網址來引用或連結此文件: http://ir.ncue.edu.tw/ir/handle/987654321/15147

題名: Spectroscopic and Computational Characterization of the Nickel-containing F430 Cofactor of Methyl-coenzyme M Reductase
作者: Craft, Jennifer L.;Horng, Yih-Chern;Ragsdale, Stephen W.;Brunold, Thomas C.
貢獻者: 化學系
關鍵詞: Cofactor F430;Density functional theory;Magnetic circular dichroism;Methyl-coenzyme M reductase;Nickel enzymes
日期: 2004-01
上傳時間: 2013-01-07T02:15:50Z
出版者: SpringerLink
摘要: Methyl-coenzyme M reductase (MCR) catalyzes the terminal reaction in methanogenesis, the formation of methane from methyl-coenzyme M and coenzyme B. The active site of MCR binds the prosthetic group F430, a unique nickel hydrocorphin cofactor. Here, spectroscopy and computations are employed in developing detailed electronic descriptions of the Ni(II) and Ni(I) forms of the free cofactor. Absorption, magnetic circular dichroism (MCD), and variable-temperature variable-field MCD data are analyzed within the framework of time-dependent DFT computations to assign key electronic transitions. DFT calculations are further employed to evaluate possible reduced F430 models—a one-electron reduced Ni(I)F430 model and a three-electron reduced Ni(I)Fred430 model (possessing a reduced hydrocorphin ligand)—on the basis of excited-state spectra and published EPR/ENDOR parameters. While calculations on both models yield spectroscopic parameters that are consistent with most experimental data, overall better agreement is achieved using the Ni(I)F430 model, particularly with respect to electronic absorption and 1H ENDOR. The experimentally validated bonding descriptions generated herein show that in Ni(II)F430 the occupied Ni 3d orbitals are too low in energy to significantly perturb the dominant electronic transition involving the and * frontier MOs of the macrocycle (i.e., the HOMOLUMO transition). Upon one-electron reduction of the Ni(II) ion, the occupied Ni 3d orbitals are raised in energy, shifting between the HOMO and the LUMO of the oxidized cofactor. These ground-state changes have a dramatic effect on the excited-state structure, causing a blue shift of the dominant * transition and the appearance of numerous Ni 3dhydrocorphin * charge-transfer features in the vis/near-IR region.
關聯: J. Biol. Inorg. Chem., 9(1): 77-89
顯示於類別:[化學系] 期刊論文

文件中的檔案:

檔案 大小格式瀏覽次數
index.html0KbHTML551檢視/開啟


在NCUEIR中所有的資料項目都受到原著作權保護.

 


DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回饋