The desaturation of positional
cis 18∶1 isomers (Δ4 through Δ11) was studied, using essential fatty acid deficient rat liver microsomes. The
cis Δ4, Δ5, Δ6 and Δ7 isomers were not desaturated. The
cis Δ10 and Δ11 isomers were desaturated at a very low rate. The maximum desaturation was obtained for Δ8 and Δ9 isomers. The
cis Δ8 and Δ11 isomers were desaturated by Δ5 desaturase; the
cis Δ9 isomer was desaturated by Δ6 desaturase; and the
cis Δ10 isomer was desaturated to Δ7,10 and 5,10–18∶2 acids.