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Main Title: Electronic and Structural Properties of the Double Cubane Iron-Sulfur Cluster
Author(s): Elghobashi-Meinhardt, Nadia
Tombolelli, Daria
Mroginski, Maria Andrea
Type: Article
Abstract: The double-cubane cluster (DCC) refers to an [Fe8S9] iron-sulfur complex that is otherwise only known to exist in nitrogenases. Containing a bridging µ2-S ligand, the DCC in the DCC-containing protein (DCCP) is covalently linked to the protein scaffold via six coordinating cysteine residues. In this study, the nature of spin coupling and the effect of spin states on the cluster’s geometry are investigated computationally. Using density functional theory (DFT) and a broken symmetry (BS) approach to study the electronic ground state of the system, we computed the exchange interaction between the spin-coupled spins of the four FeFe dimers contained in the DCC. This treatment yields results that are in excellent agreement with both computed and experimentally determined exchange parameters for analogously coupled di-iron complexes. Hybrid quantum mechanical (QM)/molecular mechanical (MM) geometry optimizations show that cubane cluster A closest to charged amino acid side chains (Arg312, Glu140, Lys146) is less compact than cluster B, indicating that electrons of the same spin in a charged environment seek maximum separation. Overall, this study provides the community with a fundamental reference for subsequent studies of DCCP, as well as for investigations of other [Fe8S9]-containing enzymes.
Subject(s): [Fe8−S9] iron-sulfur cluster
double-cubane cluster
broken symmetry
density function theory
quantum mechanics
geometry optimizations
exchange parameters
molecular mechanics
Issue Date: 12-Feb-2021
Date Available: 10-Mar-2021
Language Code: en
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Sponsor/Funder: DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"
DFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berlin
Journal Title: Catalysts
Publisher: MDPI
Volume: 11
Issue: 2
Article Number: 245
Publisher DOI: 10.3390/catal11020245
EISSN: 2073-4344
TU Affiliation(s): Fak. 2 Mathematik und Naturwissenschaften » Inst. Chemie » FG Modellierung biomolekularer Systeme
Appears in Collections:Technische Universität Berlin » Publications

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