2I0T

Crystal structure of phenylacetaldehyde derived R-carbinolamine adduct of aromatic amine dehydrogenase

2I0T の概要

• エントリーDOI: 10.2210/pdb2i0t/pdb
• 関連するPDBエントリー: 2HXC 2I0S 2IOR
• 分子名称: Aromatic amine dehydrogenase, 2-PHENYL-ETHANOL, ... (4 entities in total)
• 機能のキーワード: ttq, carbinolamine oxidation, oxidoreductase
• 由来する生物種: Alcaligenes faecalis; 詳細
• 細胞内の位置: Periplasm: P84888
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 107214.37

構造登録者

Roujeinikova, A.,Leys, D. (登録日: 2006-08-11, 公開日: 2007-04-24, 最終更新日: 2011-07-13)

主引用文献

Roujeinikova, A.,Hothi, P.,Masgrau, L.,Sutcliffe, M.J.,Scrutton, N.S.,Leys, D.
New insights into the reductive half-reaction mechanism of aromatic amine dehydrogenase revealed by reaction with carbinolamine substrates.
J.Biol.Chem., 282:23766-23777, 2007

PubMed Abstract: 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.

PubMed: 17475620
DOI: 10.1074/jbc.M700677200

実験手法

X-RAY DIFFRACTION (1.35 Å)