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2ok6
From Proteopedia
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[[Image:2ok6.gif|left|200px]] | [[Image:2ok6.gif|left|200px]] | ||
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'''Crystal structure of aromatic amine dehydrogenase TTQ-formamide adduct oxidized with ferricyanide.''' | '''Crystal structure of aromatic amine dehydrogenase TTQ-formamide adduct oxidized with ferricyanide.''' | ||
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[[Category: Leys, D.]] | [[Category: Leys, D.]] | ||
[[Category: Roujeinikova, A.]] | [[Category: Roujeinikova, A.]] | ||
| - | [[Category: | + | [[Category: Oxidoreductase]] |
| - | [[Category: | + | [[Category: Ttq]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:04:44 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 08:04, 4 May 2008
Crystal structure of aromatic amine dehydrogenase TTQ-formamide adduct oxidized with ferricyanide.
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
2OK6 is a Protein complex structure of sequences from Alcaligenes faecalis. Full crystallographic information is available from 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:17475620 Page seeded by OCA on Sun May 4 11:04:44 2008
