The ACAT-catalyzed reaction mechanism involves several steps. Initially, the enzyme binds to the substrates, cholesterol and acyl-CoA. This binding induces a conformational change in the enzyme, aligning the substrates in an optimal orientation for the transfer reaction. The catalytic residues of ACAT then facilitate the nucleophilic attack of the cholesterol hydroxyl group on the acyl-CoA, forming a tetrahedral intermediate. This intermediate collapses, releasing CoA and forming the cholesterol ester.
