sentences:  The active site contains a conserved catalytic triad of Cys164, His303 and Asn336.These residues aid in multiple decarboxylation and condensation reactions, with Cys164 acting as the active site nucleophile.Phe215 and Phe265 are two other important amino acids that act as “gatekeepers” to block the lower protein of the opening between the CoA-binding tunnel and the active site cavity.