5IKT

The Structure of Tolfenamic Acid Bound to Human Cyclooxygenase-2

5IKT の概要

• エントリーDOI: 10.2210/pdb5ikt/pdb
• 関連するPDBエントリー: 5IKQ 5IKR 5IKV
• 分子名称: Prostaglandin G/H synthase 2, alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (8 entities in total)
• 機能のキーワード: cox tolfenamic, oxidoreductase
• 由来する生物種: Homo sapiens (Human)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 131426.15

構造登録者

Orlando, B.J.,Malkowski, M.G. (登録日: 2016-03-03, 公開日: 2016-05-25, 最終更新日: 2024-11-13)

主引用文献

Orlando, B.J.,Malkowski, M.G.
Substrate-selective Inhibition of Cyclooxygeanse-2 by Fenamic Acid Derivatives Is Dependent on Peroxide Tone.
J.Biol.Chem., 291:15069-15081, 2016

PubMed Abstract: Cyclooxygenase-2 (COX-2) catalyzes the oxygenation of arachidonic acid (AA) and endocannabinoid substrates, placing the enzyme at a unique junction between the eicosanoid and endocannabinoid signaling pathways. COX-2 is a sequence homodimer, but the enzyme displays half-of-site reactivity, such that only one monomer of the dimer is active at a given time. Certain rapid reversible, competitive nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to inhibit COX-2 in a substrate-selective manner, with the binding of inhibitor to a single monomer sufficient to inhibit the oxygenation of endocannabinoids but not arachidonic acid. The underlying mechanism responsible for substrate-selective inhibition has remained elusive. We utilized structural and biophysical methods to evaluate flufenamic acid, meclofenamic acid, mefenamic acid, and tolfenamic acid for their ability to act as substrate-selective inhibitors. Crystal structures of each drug in complex with human COX-2 revealed that the inhibitor binds within the cyclooxygenase channel in an inverted orientation, with the carboxylate group interacting with Tyr-385 and Ser-530 at the top of the channel. Tryptophan fluorescence quenching, continuous-wave electron spin resonance, and UV-visible spectroscopy demonstrate that flufenamic acid, mefenamic acid, and tolfenamic acid are substrate-selective inhibitors that bind rapidly to COX-2, quench tyrosyl radicals, and reduce higher oxidation states of the heme moiety. Substrate-selective inhibition was attenuated by the addition of the lipid peroxide 15-hydroperoxyeicosatertaenoic acid. Collectively, these studies implicate peroxide tone as an important mechanistic component of substrate-selective inhibition by flufenamic acid, mefenamic acid, and tolfenamic acid.

PubMed: 27226593
DOI: 10.1074/jbc.M116.725713

実験手法

X-RAY DIFFRACTION (2.451 Å)