2VAQ

STRUCTURE OF STRICTOSIDINE SYNTHASE IN COMPLEX WITH INHIBITOR

2VAQ の概要

• エントリーDOI: 10.2210/pdb2vaq/pdb
• 関連するPDBエントリー: 2FP8 2FP9 2FPB 2FPC 2V91
• 分子名称: STRICTOSIDINE SYNTHASE, (2S,3R,4S)-methyl 4-(2-(2-(1H-indol-3-yl)ethylamino)ethyl)-2-((2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy)-3-vinyl-3,4-dihydro-2H-pyran-5-carboxylate (3 entities in total)
• 機能のキーワード: alkaloid metabolism, glycoprotein, lyase, six bladed beta propeller fold, str1, synthase, vacuole
• 由来する生物種: RAUVOLFIA SERPENTINA (SERPENTWOOD)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 72597.04

構造登録者

Maresh, J.,Giddings, L.A.,Friedrich, A.,Loris, E.A.,Panjikar, S.,Trout, B.L.,Stoeckigt, J.,Peters, B.,O'Connor, S.E. (登録日: 2007-09-04, 公開日: 2008-09-16, 最終更新日: 2024-10-16)

主引用文献

Maresh, J.J.,Giddings, L.A.,Friedrich, A.,Loris, E.A.,Panjikar, S.,Trout, B.L.,Stockigt, J.,Peters, B.,O'Connor, S.E.
Strictosidine synthase: mechanism of a Pictet-Spengler catalyzing enzyme.
J. Am. Chem. Soc., 130:710-723, 2008

PubMed Abstract: The Pictet-Spengler reaction, which yields either a beta-carboline or a tetrahydroquinoline product from an aromatic amine and an aldehyde, is widely utilized in plant alkaloid biosynthesis. Here we deconvolute the role that the biosynthetic enzyme strictosidine synthase plays in catalyzing the stereoselective synthesis of a beta-carboline product. Notably, the rate-controlling step of the enzyme mechanism, as identified by the appearance of a primary kinetic isotope effect (KIE), is the rearomatization of a positively charged intermediate. The KIE of a nonenzymatic Pictet-Spengler reaction indicates that rearomatization is also rate-controlling in solution, suggesting that the enzyme does not significantly change the mechanism of the reaction. Additionally, the pH dependence of the solution and enzymatic reactions provides evidence for a sequence of acid-base catalysis steps that catalyze the Pictet-Spengler reaction. An additional acid-catalyzed step, most likely protonation of a carbinolamine intermediate, is also significantly rate controlling. We propose that this step is efficiently catalyzed by the enzyme. Structural analysis of a bisubstrate inhibitor bound to the enzyme suggests that the active site is exquisitely tuned to correctly orient the iminium intermediate for productive cyclization to form the diastereoselective product. Furthermore, ab initio calculations suggest the structures of possible productive transition states involved in the mechanism. Importantly, these calculations suggest that a spiroindolenine intermediate, often invoked in the Pictet-Spengler mechanism, does not occur. A detailed mechanism for enzymatic catalysis of the beta-carboline product is proposed from these data.

PubMed: 18081287
DOI: 10.1021/ja077190z

実験手法

X-RAY DIFFRACTION (3.01 Å)