1iqy

<table><tr><td colspan='2'>[[1iqy]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/"achromobacter_globiformis"_(conn_1928)_bergey_et_al._1930 "achromobacter globiformis" (conn 1928) bergey et al. 1930]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IQY OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1IQY FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NI:NICKEL+(II)+ION'>NI</scene></td></tr>

<tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=TPQ:5-(2-CARBOXY-2-AMINOETHYL)-2-HYDROXY-1,4-BENZOQUINONE'>TPQ</scene></td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Oxidoreductase Oxidoreductase], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.4.3.21 and 1.4.3.22 1.4.3.21 and 1.4.3.22] </span></td></tr>

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== Publication Abstract from PubMed ==

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 &gt;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 (&lt; 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).

 

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== References ==

[[Category: Hirota, S]]

[[Category: Kim, M]]

[[Category: Kishishita, S]]

[[Category: Kuroda, S]]

[[Category: Mure, M]]

[[Category: Okajima, T]]

[[Category: Tanizawa, K]]

[[Category: Yamaguchi, H]]

[[Category: Tpq]]