Unlike the breakdown of saturated fat, cis and trans polyunsaturated fatty acid degradation requires three additional enzymes to generate a product compatible with the standard beta oxidation pathway.

Substrate length for mDECR catalysis is thought to be limited at 20 carbons, at which this very long chain fatty acid is first partially oxidized by pDECR in the peroxisome.

[10] DECR binds NADPH and the fatty acid thioester and positions them for specific hydride transfer to the Cδ on the hydrocarbon chain.

In the final step, a proton is abstracted from the water[11] to the Cα and the thioester is reformed, resulting in a single Cβ-Cγ trans double bond.

[8] 2,4 Dienoyl-CoA Reductase from Escherichia coli shares very similar kinetic properties to that of eukaryotes, but differs significantly in both structure and mechanism.

In addition to NADPH, E. Coli DECR requires a set of FAD, FMN and iron–sulfur cluster molecules to complete the electron transfer.

[11] The active site contains accurately positioned Tyr166 that donates a proton to the Cγ after hydride attack at the Cδ, completing the reduction in a single concerted step.

[8] The structure of the ternary complex of pDCR (peroxisomal 2,4-dienoyl CoA reductases) with NADP and its substrate provides essential and unique insights into the mechanism of catalysis.

Mutant subjects were also found to have poor tolerance to cold, decrease in diurnal activity, and an overall reduction in adaptation to metabolic stressors.