DHA-CoA preferentially moves back to the ER, perhaps as a free fatty acid. This conversion is usually catalysed by acyl-CoA thioesterases (ACOTs). No specific acyl-CoA thioesterase enzyme has been identified for the peroxisomal metabolism of DHA-CoA, but the peroxisomal ACOT8 has a wide substrate specificity and is likely to be responsible (Ferdinandusse et al. 2003, Hunt & Alexson. 2008).
The peroxisomal matrix enzyme acyl-coenzyme A thioesterase 8 (ACOT8) mediates the hydrolysis of choloyl-CoA to form cholate and CoASH (Jones et al. 1999, Hunt et al. 2002). While bile salts are the major product of the de novo biosynthetic pathway in the normal human liver, bile acids are major feedback regulators of this pathway and this hydrolysis reaction is thought to play a role in generating them (Russell 2003).