TY - JOUR T1 - Effects of diacylglycerols on conformation of phosphatidylcholine headgroups in phosphatidylcholine/phosphatidylserine bilayers. AU - Goldberg,E M, AU - Lester,D S, AU - Borchardt,D B, AU - Zidovetzki,R, PY - 1995/9/1/pubmed PY - 1995/9/1/medline PY - 1995/9/1/entrez SP - 965 EP - 73 JF - Biophysical journal JO - Biophys J VL - 69 IS - 3 N2 - The effects of five diacylglycerols (DAGs), diolein, 1-stearoyl,2-arachidonoyl-sn-glycerol, dioctanoylglycerol, 1-oleoyl,2-sn-acetylglycerol, and dipalmitin (DP), on the structure of lipid bilayers composed of mixtures of phosphatidylcholine and phosphatidylserine (4:1 mol/mol) were examined by 2H nuclear magnetic resonance (NMR). Dipalmitoylphosphatidylcholine deuterated at the alpha- and beta-positions of the choline moiety was used to probe the surface region of the membranes. Addition of each DAG except DP caused a continuous decrease in the beta-deuteron quadrupole splittings and a concomitant increase in the alpha-deuteron splittings indicating that DAGs induce a conformational change in the phosphatidylcholine headgroup. Additional evidence of conformational change was found at high DAG concentrations (> or = 20 mol%) where the alpha-deuteron peaks became doublets indicating that the two alpha-deuterons were not equivalent. The changes induced by DP were consistent with the lateral phase separation of the bilayers into gel-like and fluid-like domains with the phosphatidylcholine headgroups in the latter phase being virtually unaffected by DP. The DAG-induced changes in alpha-deuteron splittings were found to correlate with DAG-enhanced protein kinase C (PK-C) activity, suggesting that the DAG-induced conformational changes of the phosphatidylcholine headgroups are either directly or indirectly related to a mechanism of PK-C activation. 2H NMR relaxation measurements showed significant increase of the spin-lattice relaxation times for the region of the phosphatidylcholine headgroups, induced by all DAGs except DP. However, this effect of DAGs did not correlate with the DAG-induced activation of PK-C. SN - 0006-3495 UR - https://www.unboundmedicine.com/medline/citation/8519996/Effects_of_diacylglycerols_on_conformation_of_phosphatidylcholine_headgroups_in_phosphatidylcholine/phosphatidylserine_bilayers_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0006-3495(95)79970-2 DB - PRIME DP - Unbound Medicine ER -