Activity of human Δ5 and Δ6 desaturases on multiple n-3 and n-6 polyunsaturated fatty acids

Yeast co-expressing human elongase and desaturase genes were used to investigate whether the same desaturase gene encodes an enzyme able to desaturate n-3 and n-6 fatty acids with the same or different carbon chain length. The results clearly demonstrated that a single human Δ5 desaturase is active on 20:3n-6 and 20:4n-3. Endogenous Δ6 desaturase substrates were generated by providing to the yeast radiolabelled 20:4n-6 or 20:5n-3 which, through two sequential elongations, produced 24:4n-6 and 24:5n-3, respectively. Overall, our data suggest that a single human Δ6 desaturase is active on 18:2n-6, 18:3n-3, 24:4n-6 and 24:5n-3.