Studies on fluorescence polarization of 1-acyl-2-cis- or trans-parinaroyl sn-3-glycerophosphorylcholines in model systems and microsomal membranes.
Fluorescent lecithin probes containing cis- or trans-parinaric acid (PnA) at the 2-position cis-parinaroylphosphatidylcholine (cis-PnPC) and trans-parinaroyl phosphatidylcholine (trans-PnPC)) showed similar behavior to that of the free cis- or trans-parinaric acids (cis-PnA or trans-PnA) in bilayer vesicles of synthetic saturated lecithins. Transition temperatures detected by cis-PnPC were about 1 degree C than those observed with trans-PnPC. In mixed lecithin vesicles, the trans-PnPC probe monitored a higher temperature melting component than did the cis-probe. Both probes were readily incorporated into microsomal membranes and into sonicated vesicles prepared from the microsomal phospholipids. With either cis- or trans-PnPC no change in polarization ratio was observed for microsomal membranes between 40 degrees C and 0 degrees C but this ratio increased with decreasing temperature between 0 degrees C and -5 degrees C. However, vesicles of extracted phospholipids showed a continuous increase in polarization ratio with decreasing temperature between 20 degrees C and -15 degrees C with trans-PnPC and between 5 degrees C and -15 degrees C with cis-PnPC. These results suggest that the two lecithin probes monitor different environments in the membranes and phospholipid vesicles prepared from them.
D000818:Animals; D005227:Fatty Acids / Q000032:analysis; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005454:Fluorescence Polarization; D007536:Isomerism; D008051:Lipid Bilayers / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013056:Spectrophotometry, Ultraviolet; D013217:Starvation / Q000378:metabolism; D013696:Temperature
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008051:Lipid Bilayers; D008563:Membrane Lipids; D010713:Phosphatidylcholines; C013641:parinaric acid