Effects of constituent fatty acids on the binding of lysophosphatidylcholines by serum albumin.
The binding of lysophosphatidylcholines containing 10-18 carbons and, with 18 carbon series, up to three double bonds, to serum albumin was studied by heat-burst microcalorimetry. The heats of reaction resulting from binding the lipids and proteins in various ratios were plotted. From the plots we determined the reaction stoichiometries, then calculated the thermodynamic parameters for the reactions. We found that short-chained and unsaturated lysophosphatidylcholines are bound to albumin in a stoichiometry of 2 : 1. With longer-chained compounds the ratio becomes 1 : 1 except for the steroyl derivative, which is anomalous and bound at a ratio of 3 : 1. One explanation for this anomalous behavior is that the stearoyl lysophosphatidylcholine was bound at a temperature below its transition temperature, so it was in the gel state, while the binding of all other compounds took place above their transition temperatures when they were in a more fluid state.
D000818:Animals; D002151:Calorimetry; D005227:Fatty Acids / Q000378:metabolism*; D008244:Lysophosphatidylcholines / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000378:metabolism*; D013816:Thermodynamics
D005227:Fatty Acids; D008244:Lysophosphatidylcholines; D012710:Serum Albumin, Bovine