Enzymatic assay of phosphatidylethanolamine in serum using amine oxidase from Arthrobacter sp.

In human serum, as for phospholipids not containing choline, phosphatidylethanolamine (PE) exists approximately 5% in a whole phospholipid. PE is well known as one of the main components of biological membranes, and also plays important roles that contribute to apoptosis and cell signaling. However, it could not measure PE with other phospholipids due to a lack of choline in them. Using an amine oxidase (EC 1.4.3.6), from Arthrobacter species, a simple and rapid enzymatic assay for measurements of PE in serum was established. That assay used the Hitachi 7170 analyzer to evaluate the analytical performance. The average within-run CVs were 0.38-1.27% (n=20) at 69-160 μmol/l. The correlation between values obtained with the present method (y) and the high-performance liquid chromatography (HPLC) method (x) was: y=0.944x+9.441 (r=0.977, S(y|x)=5.82, n=34). In addition, the reference interval of healthy subjects was 115±45 μmol/l. This new enzymatic method shows a high specificity for serum PE and can be easily applied to an automated analyzer. The present method is available as a novel marker of changes in the clinical condition of serum phospholipids.