Structural Snapshots from the Oxidative Half-reaction of a Copper Amine Oxidase

Johnson, B. J.; Yukl, Erik T.; Klema, Valerie J.; Klinman, Judith P.; Wilmot, Carrie M.

doi:10.1074/jbc.m113.501791

Cited by 19 publications

(33 citation statements)

References 54 publications

(55 reference statements)

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“…A similar decrease in the number of equatorial ligands at the copper center was observed in extended x-ray absorption fine structure studies on various dithionite-treated CAOs, in which Cu(II) is reduced to Cu(I) (64). It is therefore suggested that the tetrahedrally coordinated copper centers observed in the AGAO PEA and AGAO HTA crystals are probably in the Cu(I) oxidation state, as was proposed in a recent paper on the structure of methylamine-reduced HPAO-1 (39). Based on the full occupancy of the modeled TPQ sq in the electron density map, essentially all of their TPQ is assumed to be in the TPQ sq state.…”

Section: Discussionmentioning

confidence: 58%

“…An extended x-ray absorption fine structure study (64) also raised the possibility that variations in the redox potentials or the effective electron transfer distance between TPQ amr and Cu(II) may control k ET . The difference between the rate constants for AGAO determined here (Table 2; k ϩ4 ϭ 39 s Ϫ1 at 4°C, pH 6.8) and previously (k ET ϭ 73 s Ϫ1 at 5°C, pH 7.2) (37) is probably due to subtle differences in temperature and pH, both of which strongly affect the equilibrium between TPQ amr ⅐Cu(II) and TPQ sq ⅐Cu(I) (33,35,37,39,65) (Fig. 10); at higher pH values and temperatures, the equilibrium shifts toward TPQ sq ⅐Cu(I), which suggests a ⌬H value of Ͼ0 for the conformational change of TPQ.…”

Section: Discussionmentioning

confidence: 96%

“…7, D and E) and the 5-NH 2 group positioned opposite to the catalytic base (Asp-298) in close proximity to Met-602. This is the first x-ray structure of CAO with TPQ sq being exclusively copper-ligating, although an on-copper TPQ sq structure with ϳ65-70% occupancy was recently reported for HPAO-1 crystals reduced with methylamine in a low oxygen environment at pH 8.5 (39). The copper center in AGAO PEA and AGAO HTA was tetrahedrally coordinated with the 4-OH group of TPQ at the "axial" position and the imidazole groups of three histidines (His-431, His-433, and His-592) at the "equatorial" positions.…”

Section: Effect Of Halide Ions On the Absorption Spectrum Of Tpq Sq -Itmentioning

confidence: 99%

“…The formation of the TPQ sq ⅐Cu(I) state at the beginning of the oxidative half-reaction is believed to be essential in this process. The other mechanism that has been proposed is an outer sphere process that is suggested to occur in bovine serum CAO (34) and HPAO-1 (36,39). In both of these enzymes, O 2 binds to a hydrophobic pocket close to the cofactor and is initially reduced by TPQ amr via a single electron transfer that does not change the oxidation state of the Cu(II) center.…”

mentioning

confidence: 99%

“…However, the mechanistic role of the TPQ sq ⅐ Cu(I) form in the subsequent O 2 reduction remains unclear and controversial (32)(33)(34)(35)(36)(37)(38)(39). Two reaction pathways for the O 2 reduction have been proposed, depending on the enzyme sources.…”

mentioning

confidence: 99%

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Probing the Catalytic Mechanism of Copper Amine Oxidase from Arthrobacter globiformis with Halide Ions

Murakawa

Hamaguchi

Nakanishi

et al. 2015

Journal of Biological Chemistry

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Background:Copper amine oxidases catalyze amine oxidation using copper and a quinone cofactor. Results: Halides bind axially to the copper center, preventing the reduced cofactor from adopting an on-copper conformation. Conclusion:The cofactor undergoes large conformational changes during the catalytic reaction that enable transitions between different types of chemistry. Significance: Molecular details of cofactor movement have been unveiled based on structural and kinetic evidence.

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Section: Discussionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 96%

Section: Effect Of Halide Ions On the Absorption Spectrum Of Tpq Sq -Itmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Probing the Catalytic Mechanism of Copper Amine Oxidase from Arthrobacter globiformis with Halide Ions

Murakawa

Hamaguchi

Nakanishi

et al. 2015

Journal of Biological Chemistry

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Topaquinone Biogenesis in Cu Amine Oxidases

Dooley

Brown

Shepard

2017

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Copper‐containing amine and lysyl oxidase (LOX) enzymes are responsible for catalyzing the oxidative deamination of biogenic primary amines or lysine residues in connective tissue precursor proteins. These two enzyme classes each undergo remarkable posttranslational, self‐processing reactions that are dependent solely on copper and molecular oxygen. The formation of the mature enzymes involves oxidation of an absolutely conserved tyrosine residue within the polypeptide sequence of the protein and results in formation of a quinone species. The autocatalytic process generates trihydroxyphenylalanine quinone (TPQ) in copper‐containing amine oxidases (CuAO) and lysyl tyrosine quinone (LTQ) in LOXs. The discovery of TPQ was the first of its kind and helped establish a new paradigm in biology for the modification and synthesis of amino acid derivatives that in turn exhibit unique chemical functionality. For copper‐containing amine and LOX enzymes, the quinone cofactors themselves are responsible for the coordination of amine substrates in Schiff base complexes, which then can be hydrolyzed to yield aldehyde product and a reduced aminoquinol that must then be reoxidized to afford the resting state of the enzyme. In terms of the biogenesis mechanisms, the tyrosine residue that undergoes oxidation is bound in close proximity to a type II copper center. Initial steps in TPQ and LTQ biosynthesis are proposed to be identical, and one possibility invokes coordination of tyrosine to copper(II) to introduce some radical or charge‐transfer character into the ring that could increase susceptibility to attack by molecular oxygen to yield a copper(II)‐peroxoquinone species; this moiety is then converted into 3,4‐dihydroxyphenylalanine quinone or dopaquinone. At this stage, TPQ biogenesis proceeds through attack of solvent water or hydroxide to the O2 position of the ring, whereas LTQ biogenesis proceeds through attack of a conserved polypeptide‐derived lysine residue to the O2 position of the ring. This chapter summarizes the discoveries of TPQ and LTQ and the large repertoire of experimental work that has gone into understanding the biogenesis mechanisms for these two extraordinary biological cofactors.

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Quantitative Electromerism of a Well‐defined Mononuclear Copper Complex Through Reversible Intramolecular Metal‐Ligand Electron Transfer

Osterbrink

Walter

Leingang

et al. 2023

Chemistry A European J

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Copper amine oxidases are enzymes that exhibit in their active site a mononuclear copper complex and a 2,4,5‐trihydroxyphenylalanine quinone (TPQ) cofactor; in the oxidative half of the catalytic cycle, the enzymes regulate their activity by a temperature‐dependent electron transfer equilibrium between the CuII complex with the reduced, aminoquinol form of the cofactor and the reactive CuI complex with the corresponding oxidized, semiquinone form of the cofactor. Here, we report the first mononuclear copper complex with redox‐active ligands showing quantitative, reversible electromerism between a CuII eletromer with reduced, neutral ligand and a CuI electromer with an oxidized, radical monocationic ligand. The CuII form, being exclusively present at low temperature, exhibits a lower enthalpy (like the enzymes), but the CuI complex exhibits a higher entropy and is exclusively present at room temperature in CH2Cl2 solution. Further analysis, based on six different copper complexes, discloses a large solvent effect on electromerism.

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Structural Snapshots from the Oxidative Half-reaction of a Copper Amine Oxidase

Cited by 19 publications

References 54 publications

Probing the Catalytic Mechanism of Copper Amine Oxidase from Arthrobacter globiformis with Halide Ions

Probing the Catalytic Mechanism of Copper Amine Oxidase from Arthrobacter globiformis with Halide Ions

Topaquinone Biogenesis in Cu Amine Oxidases

Quantitative Electromerism of a Well‐defined Mononuclear Copper Complex Through Reversible Intramolecular Metal‐Ligand Electron Transfer

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