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The effect of isomeric trans ‐18∶1 acids on the desaturation of palmitic, linoleic and eicosa‐8,11,14‐trienoic acids by rat liver microsomes
Author(s) -
Mahfouz M. M.,
Johnson S.,
Holman R. T.
Publication year - 1980
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02533884
Subject(s) - lipidology , clinical chemistry , microsome , palmitic acid , chemistry , biochemistry , linoleic acid , microsoma , food science , fatty acid , enzyme
The inhibitory effects of the positional isomers of trans ‐18∶1 acids on the desaturation of palmitic acid to palmitoleic (Δ9‐desaturase), linoleic to γ‐linolenic (Δ6‐desaturase) and eicosa‐8,11,14‐trienoic to arachidonic acid (Δ5‐desaturase) were investigated. These trans ‐18∶1 acids were found to be inhibitory for the microsomal Δ6‐, Δ9‐ and Δ5‐desaturases of rat liver. The position of the double bond in the trans ‐18∶1 acids seems to be important in determining the degree of inhibition. At inhibitor/substrate ratio of 3∶1, the Δ6‐desaturase was most strongly inhibited by trans ‐Δ3,‐Δ4,‐Δ7 and‐Δ15‐18∶1 isomers, whereas the Δ9‐desaturase was most strongly inhibited by trans ‐Δ3,‐Δ5,‐Δ7,‐Δ10,‐Δ12,‐Δ13 and‐Δ16 isomers. At inhibitor/substrate ratio of 6∶1, the Δ5‐desaturase was most strongly inhibited by Δ3‐, Δ9‐, Δ13‐ and Δ15‐isomers. When 18∶0 was added to the incubations of 16∶0, 18∶2 and 20∶3 at the same I/S ratios used for the trans ‐18∶1 acids, weak inhibition for Δ9‐desaturase and no inhibition for Δ5‐and Δ6‐desaturases was observed.