Understanding the Molecular Mechanism of the Ala-versus-Gly Concept Controlling the Product Specificity in Reactions Catalyzed by Lipoxygenases: A Combined Molecular Dynamics and QM/MM Study of Coral 8R-Lipoxygenase

Lipoxygenases (LOXs) are a family of enzymes that catalyze the highly specific hydroperoxidation of polyunsaturated fatty acids, such as arachidonic acid. Different stereo- or/and regioisomer hydroperoxidation products lead later to different metabolites that exert opposite physiological effects in the animal body and play a central role in inflammatory processes. The Gly-Ala switch of a single residue is crucial for the stereo- and regiocontrol in many lipoxygenases. Herein, we have combined molecular dynamics simulations with quantum mechanics/molecular mechanics calculations to study the hydrogen abstraction step and the molecular oxygen addition step of the hydroperoxidation reaction of arachidonic acid catalyzed by both wild-type Coral 8R-LOX and its Gly427Ala mutant. We have obtained a detailed molecular understanding of this Ala-versus-Gly concept. In wild type, molecular oxygen adds to C8 of arachidonic acid with an R stereochemistry. In the mutant, Ala427 pushes Leu385, blocks the region over C8,...