Direct
Copper(III) Formation from O<sub>2</sub> and
Copper(I) with Histamine Ligation
J. Brannon Gary
Cooper Citek
Timothy
A. Brown
Richard N. Zare
Erik C. Wasinger
T. Daniel P. Stack
10.1021/jacs.6b05538.s001
https://acs.figshare.com/articles/journal_contribution/Direct_Copper_III_Formation_from_O_sub_2_sub_and_Copper_I_with_Histamine_Ligation/3503960
Histamine chelation of copper(I)
by a terminal histidine residue
in copper hydroxylating enzymes activates dioxygen to form unknown
oxidants, generally assumed as copper(II) species. The direct formation
of copper(III)-containing products from the oxygenation of histamine-ligated
copper(I) complexes is demonstrated here, indicating that copper(III)
is a viable oxidation state in such products from both kinetic and
thermodynamic perspectives. At low temperatures, both trinuclear Cu(II)<sub>2</sub>Cu(III)O<sub>2</sub> and dinuclear Cu(III)<sub>2</sub>O<sub>2</sub> predominate, with the distribution dependent on the histamine
ligand structure and oxygenation conditions. Kinetics studies suggest
the bifurcation point to these two products is an unobserved peroxide-level
dimer intermediate. The hydrogen atom reactivity difference between
the trinuclear and binuclear complexes at parity of histamine ligand
is striking. This behavior is best attributed to the accessibility
of the bridging oxide ligands to exogenous substrates rather than
a difference in oxidizing abilities of the clusters.
2016-07-28 12:48:34
copper hydroxylating enzymes activates dioxygen
exogenous substrates
oxygenation conditions
oxidation state
oxidizing abilities
histamine ligand
O 2
oxide ligands
Histamine Ligation Histamine chelation
terminal histidine residue
bifurcation point
Kinetics studies
hydrogen atom reactivity difference
histamine ligand structure
Cu