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Compound I in horseradish peroxidase enzyme: Magnetic state assessment by quadratric configuration interaction calculations
Author(s) -
Zazza Costantino,
Sanico,
Tatoli Simone,
Aschi Massimiliano,
Palma Amedeo
Publication year - 2010
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22267
Subject(s) - horseradish peroxidase , chemistry , wave function , multiplicity (mathematics) , computational chemistry , density functional theory , catalytic cycle , atomic physics , catalysis , physics , enzyme , organic chemistry , mathematical analysis , mathematics
Quadratic configuration interaction procedure with single and double electronic excitations (QCISD) has been used, for the first time, to calculate the electronic structure of the Compound I (CpdI), which represents a key intermediate in the catalytic cycle of Horseradish Peroxidase (HRP) enzyme. The QCISD method is applied to lowest quasi‐isoenergetic doublet and quartet spin multiplicity and results compared with density functional theory (DFT/B3LYP) data. This investigation shows that, at present, QCISD is more accurate than DFT‐based approach in discriminating between the two lowest magnetic states of CpdI complex in HRP enzyme. Such a result opens the possibility of theoretically addressing the reaction mechanism leading to CpdI complex in HRP using a correlated wavefunction based approach. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010