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spinqualitylabelsall models Enoyl-ACP Reductase InhA Homotetramer Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Contents 1 Introduction 1.1 FAS-II System 1.2 Mechanism of Action 2 General Structural Information 2.1 Fatty Acyl Binding Crevice 2.2 Catalytic Triad 2.3 Hydrogen Bonding Interactions 3 Clinical Applications

Introduction

FAS-II System

Mechanism of Action

General Structural Information

Crystal structures of InhA reveal a (each subunit featured with a different color) in aqueous solution with separate ligand binding sites in each subunit. Each subunit is composed of 289 residues and features a typical Rossmann fold containing a single NADH binding site. The of InhA is made up of several alpha helices (pink), beta sheets (gold), and beta turns (white). This enzyme also features a fatty acyl binding crevice that accommodates the long-chain fatty acyl substrate needed to synthesize mycolic acid precursors. The of the InhA form one side of the fatty acyl binding crevice, referred to as the (residues 196-219). One side of this crevice is open and exposed to solvent, which allows the substrates to access the binding pocket of this enzyme. The size of the substrate binding loop is a primary determinant of the ability of InhA to select for fatty acyl chains longer than 16 carbons to successfully produce mycolic acid precursors.

Talk generally about catalytic triad. More specific details in sections below.

Fatty Acyl Binding Crevice

Within the fatty acyl binding crevice, the NADH substrate sits on the top shelf of the Rossmann fold, and the fatty acyl substrate sits on top of the NADH substrate. Both of these substrates are held in place through interactions with the side chains of (purple) residues. The majority of these residues anchoring the substrates are found within the substrate binding loop itself, including Ala-198, Met-199, Ala-201, Ile-202, Leu-207, Ile-215, and Leu-218. Studies have found that the fatty acyl substrate adopts a u-shaped conformation to facilitate binding.

Catalytic Triad

Hydrogen Bonding Interactions

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Clinical Applications

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