INTERACTION OF RAT-LIVER MICROSOMES CONTAINING SATURATED OR UNSATURATED FATTY-ACIDS WITH FATTY-ACID-BINDING PROTEIN - PEROXIDATION EFFECT

In the studies described here rat liver microsomes containing labeled palmitic, stearic, oleic or linoleic acids were incubated with fatty a cid binding protein (FABP) and the rate of removal of C-14-labeled fat ty acids from the membrane by the soluble protein was measured using a model system. More unsaturated than saturated fatty acids were remove d from native liver mircrosomes incubated with similar amounts of FABP . The in vitro peroxidation of microsomal membranes mediated by ascorb ate-Fe++, modified its fatty acid composition with a considerable decr ease of the peroxidizability index. These changes in the microsomes fa cilitated the removal of oleic and linoeic acids by FABP, but the remo val of palmitic and stearic acids was not modified. This effect is pro posed to result from a perturbation of membrane structure following pe roxidation with release of free fatty acids from susceptible domains.