1iu7
From Proteopedia
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'''HOLO FORM OF COPPER-CONTAINING AMINE OXIDASE FROM ARTHROBACTER GLOBIFORMIS''' | '''HOLO FORM OF COPPER-CONTAINING AMINE OXIDASE FROM ARTHROBACTER GLOBIFORMIS''' | ||
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==Reference== | ==Reference== | ||
Role of copper ion in bacterial copper amine oxidase: spectroscopic and crystallographic studies of metal-substituted enzymes., Kishishita S, Okajima T, Kim M, Yamaguchi H, Hirota S, Suzuki S, Kuroda S, Tanizawa K, Mure M, J Am Chem Soc. 2003 Jan 29;125(4):1041-55. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12537504 12537504] | Role of copper ion in bacterial copper amine oxidase: spectroscopic and crystallographic studies of metal-substituted enzymes., Kishishita S, Okajima T, Kim M, Yamaguchi H, Hirota S, Suzuki S, Kuroda S, Tanizawa K, Mure M, J Am Chem Soc. 2003 Jan 29;125(4):1041-55. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12537504 12537504] | ||
| - | [[Category: Amine oxidase (copper-containing)]] | ||
[[Category: Arthrobacter globiformis]] | [[Category: Arthrobacter globiformis]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: Tanizawa, K.]] | [[Category: Tanizawa, K.]] | ||
[[Category: Yamaguchi, H.]] | [[Category: Yamaguchi, H.]] | ||
| - | [[Category: | + | [[Category: Amine oxidase]] |
| - | [[Category: | + | [[Category: Arthrobacter globiformi]] |
| - | [[Category: | + | [[Category: Copper]] |
| - | [[Category: | + | [[Category: Oxidoreductase]] |
| - | [[Category: | + | [[Category: Quinone cofactor]] |
| - | [[Category: | + | [[Category: Tpq]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 20:25:14 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 17:25, 2 May 2008
HOLO FORM OF COPPER-CONTAINING AMINE OXIDASE FROM ARTHROBACTER GLOBIFORMIS
Overview
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).
About this Structure
1IU7 is a Single protein structure of sequence from Arthrobacter globiformis. Full crystallographic information is available from OCA.
Reference
Role of copper ion in bacterial copper amine oxidase: spectroscopic and crystallographic studies of metal-substituted enzymes., Kishishita S, Okajima T, Kim M, Yamaguchi H, Hirota S, Suzuki S, Kuroda S, Tanizawa K, Mure M, J Am Chem Soc. 2003 Jan 29;125(4):1041-55. PMID:12537504 Page seeded by OCA on Fri May 2 20:25:14 2008
