Electronic structures of exchange coupled trigonal trimeric Cu(II) complexes: Spin frustration, antisymmetric exchange, pseudo-A terms, and their relation to O2 activation in the multicopper oxidases

The two oxidized forms of the trinuclear Cu cluster in the multicopper oxidases and mechanism for the decay of the native intermediate

“…In addition, variable-temperature variable-field (VTVH) MCD data indicate a doublet ground state and the presence of a low-lying excited doublet state at Ϸ30 cm Ϫ1 (B.D.L., J.Y., and E.I.S., unpublished manuscript). These properties cannot be derived from an isolated mono-or binuclear Cu site (21) but from an all-bridged Cu(II) trimer with three comparable J values (22,23). The ͉A ʈ ͉ value of 93 ϫ 10 Ϫ4 cm Ϫ1 is Ϸ60% of that of typical tetragonal Cu(II) complexes.…”

Theoretical studies of the active-site structure, spectroscopic and thermodynamic properties, and reaction mechanism of multicopper oxidases

“…As can be seen in Table 1, a dioxygen ligand is present in some of the crystal structures [11,19,20,21,22,24,25] and its presence is also supported by paramagnetic NMR studies [34]. Since inorganic experience, spectroscopic data, and computational studies tell us that O 2 binds only to Cu + [8,9,10,13], this indicates that such structures are reduced during data collection.…”

“…It should be noted that alternative mechanisms, with O 2 binding to the fully oxidised state, have also been suggested, based on crystal structures [11]. However, such a mechanism has been hard to reconcile with available inorganic, kinetic, and computational data [8,9,10,13] and it does not take into account the fact that crystal structures are photoreduced during data collection.…”

“…In the early 1990s, this hypothesis was confirmed by the crystal structures of ascorbate oxidase [5], showing a TNC, consisting of a pair of type 3 copper ions (Cu-T3), coordinated to three histidine groups each and in the oxidised state bridged by an oxo or hydroxide ion, and one type 2 copper ion (Cu-T2), coordinated by two histidine residues and a water molecule or hydroxide ion ( Figure 1). Most of these achievements are well documented in many extensive and excellent reviews [2,6,7,8,9,10,11] on the MCO structure, reactivity and spectroscopy written over the years, which also provide a historical record of the evolution of our understanding of their complex molecular architecture. coupled with the various accessible protonation states of the copper ligands originating from water or dioxygen (e.g.…”

From Hartree–Fock to Electron Correlation: Application to Magnetic Systems

“…From a fundamental point of view, high-T c superconducting copper oxides [3][4][5], and colossal magnetoresistant manganite oxides [6][7][8][9][10][11] are such families which cannot be ignored in the field of two-and three-dimensional materials. One-dimensional chains [12][13][14][15] as well as molecular systems mimicking biological active centers [16,17] have more recently been considered as promising targets in the understanding of dominant electronic interactions. In such materials, a rather limited number of electrons are responsible for the observed intriguing properties.…”