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2ok6

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[[Image:2ok6.gif|left|200px]]
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[[Image:2ok6.png|left|200px]]
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{{STRUCTURE_2ok6| PDB=2ok6 | SCENE= }}
{{STRUCTURE_2ok6| PDB=2ok6 | SCENE= }}
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'''Crystal structure of aromatic amine dehydrogenase TTQ-formamide adduct oxidized with ferricyanide.'''
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===Crystal structure of aromatic amine dehydrogenase TTQ-formamide adduct oxidized with ferricyanide.===
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==Overview==
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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.
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(as it appears on PubMed at http://www.pubmed.gov), where 17475620 is the PubMed ID number.
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{{ABSTRACT_PUBMED_17475620}}
==About this Structure==
==About this Structure==
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[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
[[Category: Ttq]]
[[Category: Ttq]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 11:04:44 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 17:17:09 2008''

Revision as of 14:17, 27 July 2008

Image:2ok6.png

Template:STRUCTURE 2ok6

Crystal structure of aromatic amine dehydrogenase TTQ-formamide adduct oxidized with ferricyanide.

Template:ABSTRACT PUBMED 17475620

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 Jul 27 17:17:09 2008

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