Determination of HDL phosphatidyl choline by an enzymatic method

Abstract

A routine method is described for the enzymatic determination of phosphatidyl choline in the apolipoprotein B-free supernatant after precipitation of blood sera with phosphotungstic acid/MgCl2. The principle of this method is based on the specific cleavage of phosphatidyl choline by purified phospholipase C from B. cereus, and the enzymatic determination of choline by choline kinase after hydrolysis of phosphoryl-choline. The enzymatic method provides HDL phosphatidyl choline values which coincide with those of the conventional chemical method. Furthermore, the values obtained with the enzymatic method for the HDL fraction isolated by ultracentrifugation (1.063--1.21 kg/l) also closely coincide with those of the apolipoprotein B-free supernatant fraction. The precision, linearity and sample stability were also checked. The findings obtained show that the enzymatic assay introduced here is suitable for the routine determination of phosphatidyl choline in the apolipoprotein B-free supernatant.