Coordination environment and fluoride binding of type 2 copper in the blue copper protein ascorbate oxidase

Dawson, John H.; Dooley, David M.; Gray, Harry B.

doi:10.1073/pnas.77.9.5028

Cited by 10 publications

(2 citation statements)

References 36 publications

(44 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2 Another peculiar aspect of the phenol-bound form of AO is the observation of type 1 copper reduction when azide is present. Reduction of type 1 Cu has been observed by reaction of the enzyme with nitric oxide (Dawson et al, 1980;Gorren et al, 1987) or, as the primary event, with radicals produced by pulse radiolysis (O'Neill et al, 1983), or photochemically (Meyer et al, 1991;Farver & Pecht, 1994;Tollin et al, 1993;Hazzard et al, 1994). Type 1 copper is also the primary electron acceptor from the reducing substrate (Kroneck et al, 1982;Mondovı `& Avigliano, 1984;Sakurai et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

et al. 1997

View full text Add to dashboard Cite

Competitive inhibition by phenolic compounds of the ascorbic acid oxidation reaction catalyzed by ascorbate oxidase was investigated at pH 7.0 and 23.0 degrees C. Inhibition of p-nitrophenol is pH dependent over the range 5.0-8.0, with inhibitor binding favored at higher pH. Bulky substituents on the phenol nucleus reduce or prevent the inhibitory effect. The presence of phenol affects the binding characteristics of azide to the trinuclear cluster of the enzyme. In particular, binding of azide to type 2 copper is prevented, and the affinity of azide to type 3 copper is reduced. In addition, reduction of type 1 copper is observed upon prolonged incubation of ascorbate oxidase with excess phenol and azide, but not with phenol alone. It is proposed that binding of phenolic inhibitors occurs at or near the site where the substrate (ascorbate) binds. NMR relaxation measurements of the protons of phenols in the presence of ascorbate oxidase show paramagnetic effects due to the proximity of the bound inhibitor to a copper center, likely type 1 copper. Copper-proton distance estimates between this paramagnetic center and p-cresol or p-nitrophenol bound to ascorbate oxidase are between 4.4 and 5.9 A.

show abstract

Section: Discussionmentioning

confidence: 99%

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

et al. 1997

View full text Add to dashboard Cite

show abstract

“…However, it is more weakly bound than the type 1 copper as evidenced by its selective removal by the EDTA wash. Type 2 copper centers exhibit square planar geometry with visible absorption spectra that lack distinctive features (36) and, therefore, do not contribute to the absorbance maxima centered around 595 nm. This explains why after EDTA treatment the copper content of the reconstituted M98Q amicyanin decreased to 0.61 per molecule, with no concomitant decrease in A 595 .…”

Section: Effects Of the Introduction Of Glutamine As An Axialmentioning

confidence: 99%

Generation of Novel Copper Sites by Mutation of the Axial Ligand of Amicyanin. Atomic Resolution Structures and Spectroscopic Properties^,

Carrell

Antholine

et al. 2007

Biochemistry

View full text Add to dashboard Cite

Amicyanin from Paracoccus denitrificans is a type 1 copper protein with three strong equatorial copper ligands provided by nitrogens of His53 and His95 and the sulfur of Cys92, with an additional weak axial ligand provided by the sulfur of Met98. Met98 was replaced with either Gln or Ala. As isolated, the M98A and M98Q mutant proteins contain zinc in the active site. The zinc is then removed and replaced with copper so that the copper-containing proteins may be studied. Each of the mutant amicyanins exhibits a marked decrease in thermal stability relative to that of native amicyanin, consistent with the weaker affinity for copper. Crystal structures were obtained for the oxidized and reduced forms of M98A and M98Q amicyanins at atomic resolution (

show abstract

Ceruloplasmin

Lindley¹

2004

Handbook of Metalloproteins

View full text Add to dashboard Cite

Ceruloplasmin is a multi‐copper oxidase that contains most of the copper present in the plasma. It is an acute‐phase reactant that exhibits a two‐ to three‐fold increase over the normal concentration of 300 mg ml −1 in adult plasma. However, the precise physiological role(s) of ceruloplasmin has been the subject of intensive debate and it is likely that the enzyme has a multi‐functional role, including iron oxidase activity and oxidation of biogenic amines. The three‐dimensional X‐ray structure of the human enzyme shows that the molecule is composed of six cupredoxin‐type domains arranged in a triangular array. There are six integral copper atoms per molecule (mononuclear sites in domains 2, 4, and 6 and a trinuclear site between domains 1 and 6) and two labile sites with roughly 50% occupancy. Further structural studies on the binding of metal cations by the enzyme have indicated a putative mechanism for ferroxidase activity. Other studies have located the binding sites for an inhibitor (azide) and various substrates [aromatic diamines, biogenic amines, and D ‐lysergic acid diethylamide (LSD)]. The binding site of the azide moiety is topologically equivalent to one of the sites reported for ascorbate oxidase. However, there are two distinct binding sites for amine substrates; aromatic diamines bind at the base of domain 4 remote from the mononuclear copper site, whereas the biogenic amine series typified by serotonin, epinephrine, and dopa bind in close vicinity to that site utilized by cations in domain 6 and close to the mononuclear copper.

show abstract

Coordination environment and fluoride binding of type 2 copper in the blue copper protein ascorbate oxidase

Abstract: The coordination environment of the type 2

Cited by 10 publications

References 36 publications

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

Generation of Novel Copper Sites by Mutation of the Axial Ligand of Amicyanin. Atomic Resolution Structures and Spectroscopic Properties^,

Ceruloplasmin

Contact Info

Product

Resources

About

Coordination environment and fluoride binding of type 2 copper in the blue copper protein ascorbate oxidase

Abstract: The coordination environment of the type 2

Cited by 10 publications

References 36 publications

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies

Generation of Novel Copper Sites by Mutation of the Axial Ligand of Amicyanin. Atomic Resolution Structures and Spectroscopic Properties,

Ceruloplasmin

Contact Info

Product

Resources

About

Generation of Novel Copper Sites by Mutation of the Axial Ligand of Amicyanin. Atomic Resolution Structures and Spectroscopic Properties^,