PDBsum entry: 1iqy

Oxidoreductase

PDB id: 1iqy

Contents

Protein chains

620 a.a. *

Metals

_NI ×2

Waters ×908

* Residue conservation analysis

PDB id:

1iqy

Name:

Oxidoreductase

Title:

Crystal structure of nickel-substituted amine oxidase from arthrobacter globiformis

Structure:

Amine oxidase. Chain: a, b. Synonym: phenylethylamine oxidase. Engineered: yes

Source:

Arthrobacter globiformis. Organism_taxid: 1665. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PQS)

Resolution:

1.80Å R-factor: 0.208 R-free: 0.260

Authors:

S.Kishishita,T.Okajima,M.Mure,M.Kim,H.Yamaguchi,S.Hirota, S.Kuroda,K.Tanizawa

Key ref:

S.Kishishita et al. (2003). Role of copper ion in bacterial copper amine oxidase: spectroscopic and crystallographic studies of metal-substituted enzymes. J Am Chem Soc, 125, 1041-1055. PubMed id: 12537504 DOI: 10.1021/ja017899k

Date:

28-Aug-01 Release date: 04-Feb-03

Protein chains

P46881  (PAOX_ARTGO) -  Phenylethylamine oxidase

Seq: 638 a.a.

Struc: 620 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.4.3.21 - Primary-amine oxidase.
• Reaction: RCH₂NH₂ + H₂O + O₂ = RCHO + NH₃ + H₂O₂

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Biological process: oxidation reduction (2 terms)
• Biochemical function: oxidoreductase activity (5 terms)

reference

DOI no: 10.1021/ja017899k

J Am Chem Soc 125:1041-1055 (2003)

PubMed id: 12537504

Role of copper ion in bacterial copper amine oxidase: spectroscopic and crystallographic studies of metal-substituted enzymes.

S.Kishishita, T.Okajima, M.Kim, H.Yamaguchi, S.Hirota, S.Suzuki, S.Kuroda, K.Tanizawa, M.Mure.

ABSTRACT

The role of the active site Cu(2+) of phenylethylamine oxidase from Arthrobacter globiformis (AGAO) has been studied by substitution with other divalent cations, where we were able to remove >99.5% of Cu(2+) from the active site. The enzymes reconstituted with Co(2+) and Ni(2+) (Co- and Ni-AGAO) exhibited 2.2 and 0.9% activities, respectively, of the original Cu(2+)-enzyme (Cu-AGAO), but their K(m) values for amine substrate and dioxygen were comparable. X-ray crystal structures of the Co- and Ni-AGAO were solved at 2.0-1.8 A resolution. These structures revealed changes in the metal coordination environment when compared to that of Cu-AGAO. However, the hydrogen-bonding network around the active site involving metal-coordinating and noncoordinating water molecules was preserved. Upon anaerobic mixing of the Cu-, Co-, and Ni-AGAO with amine substrate, the 480 nm absorption band characteristic of the oxidized form of the topaquinone cofactor (TPQ(ox)) disappeared rapidly (< 6 ms), yielding the aminoresorcinol form of the reduced cofactor (TPQ(amr)). In contrast to the substrate-reduced Cu-AGAO, the semiquinone radical (TPQ(sq)) was not detected in Co- and Ni-AGAO. Further, in the latter, TPQ(amr) reacted reversibly with the product aldehyde to form a species with a lambda(max) at around 350 nm that was assigned as the neutral form of the product Schiff base (TPQ(pim)). Introduction of dioxygen to the substrate-reduced Co- and Ni-AGAO resulted in the formation of a TPQ-related intermediate absorbing at around 360 nm, which was assigned to the neutral iminoquinone form of the 2e(-)-oxidized cofactor (TPQ(imq)) and which decayed concomitantly with the generation of TPQ(ox). The rate of TPQ(imq) formation and its subsequent decay in Co- and Ni-AGAO was slow when compared to those of the corresponding reactions in Cu-AGAO. The low catalytic activities of the metal-substituted enzymes are due to the impaired efficiencies of the oxidative half-reaction in the catalytic cycle of amine oxidation. On the basis of these results, we propose that the native Cu(2+) ion has essential roles such as catalyzing the electron transfer between TPQ(amr) and dioxygen, in part by providing a binding site for 1e(-)- and 2e(-)-reduced dioxygen species to be efficiently protonated and released and also preventing the back reaction between the product aldehyde and TPQ(amr).