2oiz: Difference between revisions
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caption="2oiz, resolution 1.050Å" /> | caption="2oiz, resolution 1.050Å" /> | ||
'''Crystal Structure of the Tryptamine-Derived (Indol-3-Acetamide)-TTQ Adduct of Aromatic Amine Dehydrogenase'''<br /> | '''Crystal Structure of the Tryptamine-Derived (Indol-3-Acetamide)-TTQ Adduct of Aromatic Amine Dehydrogenase'''<br /> | ||
==Overview== | |||
Aromatic amine dehydrogenase uses a tryptophan tryptophylquinone (TTQ), cofactor to oxidatively deaminate primary aromatic amines. In the, reductive half-reaction, a proton is transferred from the substrate C1 to, betaAsp-128 O-2, in a reaction that proceeds by H-tunneling. Using, solution studies, kinetic crystallography, and computational simulation we, show that the mechanism of oxidation of aromatic carbinolamines is similar, to amine oxidation, but that carbinolamine oxidation occurs at a, substantially reduced rate. This has enabled us to determine for the first, time the structure of the intermediate prior to the H-transfer/reduction, step. The proton-betaAsp-128 O-2 distance is approximately 3.7A, in, contrast to the distance of approximately 2.7A predicted for the, intermediate formed with the corresponding primary amine substrate. This, difference of approximately 1.0 A is due to an unexpected conformation of, the substrate moiety, which is supported by molecular dynamic simulations, and reflected in the approximately 10(7)-fold slower TTQ reduction rate, with phenylaminoethanol compared with that with primary amines. A water, molecule is observed near TTQ C-6 and is likely derived from the collapse, of the preceding carbinolamine TTQ-adduct. We suggest this water molecule, is involved in consecutive proton transfers following TTQ reduction, and, is ultimately repositioned near the TTQ O-7 concomitant with protein, rearrangement. For all carbinolamines tested, highly stable amide-TTQ, adducts are formed following proton abstraction and TTQ reduction. Slow, hydrolysis of the amide occurs after, rather than prior to, TTQ oxidation, and leads ultimately to a carboxylic acid product. | |||
==About this Structure== | ==About this Structure== | ||
2OIZ is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Alcaligenes_faecalis Alcaligenes faecalis] with <scene name='pdbligand=TSR:'>TSR</scene> and <scene name='pdbligand=PG4:'>PG4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Aralkylamine_dehydrogenase Aralkylamine dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.4.99.4 1.4.99.4] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2OIZ OCA]. | 2OIZ is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Alcaligenes_faecalis Alcaligenes faecalis] with <scene name='pdbligand=TSR:'>TSR</scene> and <scene name='pdbligand=PG4:'>PG4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Aralkylamine_dehydrogenase Aralkylamine dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.4.99.4 1.4.99.4] Known structural/functional Sites: <scene name='pdbsite=AC1:Tsr+Binding+Site+For+Residue+H+1701'>AC1</scene>, <scene name='pdbsite=AC2:Tsr+Binding+Site+For+Residue+D+1702'>AC2</scene> and <scene name='pdbsite=AC3:Pg4+Binding+Site+For+Residue+A+1700'>AC3</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2OIZ OCA]. | ||
==Reference== | |||
New insights into the reductive half-reaction mechanism of aromatic amine dehydrogenase revealed by reaction with carbinolamine substrates., Roujeinikova A, Hothi P, Masgrau L, Sutcliffe MJ, Scrutton NS, Leys D, J Biol Chem. 2007 Aug 17;282(33):23766-77. Epub 2007 May 1. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17475620 17475620] | |||
[[Category: Alcaligenes faecalis]] | [[Category: Alcaligenes faecalis]] | ||
[[Category: Aralkylamine dehydrogenase]] | [[Category: Aralkylamine dehydrogenase]] | ||
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[[Category: tryptophan tryptophyl quinone]] | [[Category: tryptophan tryptophyl quinone]] | ||
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