This page shows some interactive JSmol views of several type 2 copper oxidase enzymes
The first figure [PHM] shows the structure of the copper monooxygenase enzyme
peptidylglycine α-hydroxylating monooxygenase (PHM), its function is to carry out regio- and stereospecific
hydroxylation of secondary C-H bonds. Note that, although the structure appears to have two similar domains,
it is not a dimer.
The protein contains two copper ions but they are separated by about 10 Å
(check for yourself) - so they are not coupled together. One site (that shown on the right with 3 His ligands)
is probably an electron transfer site; the other is the active site for the catalysis.
[PHM2] shows the active site with dioxygen bound to the active site
(as Cu(II)—O2·–). This form is produced by reaction of O2
The active site also contains a small peptide in the active site - this is the substrate that will be hydroxylated
(in the case of this particular substrate, N-acetyl-3,5-diiodotyrosyl-D-threonine, the reaction is slow).
Measure the bonds in the Cu(II)—O2·– assembly. Are they consistent with this
description?
Quercetinase is a type 2 copper dioxygenase - the only copper dioxygenase known and a very rare example of a copper metalloprotein
with a carboxylate ligand. The figure shows the exzyme-substrate complex with quercetin bound to the copper center.
Galactose oxidase and the class of amine oxidases catalyse two-electron oxidation. Since only one electron can come from the copper
another redox-active cofactor is needed.
Both enzymes contain modified groups synthesised by the enzyme itself after its initial assembly.
In amine oxidases a tyrosine residue is oxidised to 2,4,5-trihydroxyl-phenylalanine quinone (TPQ) ; in
galactose oxidase a tyrosine is
crosslinked to a cysteine. Both modified groups sit in the active site but not bound to the copper ion.
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