Automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid.
We describe methods for automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid. Phospholipase C (EC 3.1.4.3) and sphingomyelin phosphodiesterase (EC 3.1.4.12) are reacted with lecithin and sphingomyelin, respectively, to liberate phosphocholine. Phosphocholine is then reacted with alkaline phosphatase, choline oxidase, peroxidase, and 4-aminoantipyrine to form a colored complex, for which the absorbance at 500 nm is measured with a centrifugal analyzer. Phosphatidylglycerol is hydrolyzed by phospholipase D (EC 3.1.4.4) to form glycerol, which is subsequently reacted with ATP and NAD+ in the presence of glycerol kinase and glycerol-3-phosphate dehydrogenase to yield NADH. The absorbance of the NADH formed is measured at 340 nm. These methods provide a simple, rapid, and accurate alternative to thin-layer chromatography for determination of phospholipids in amniotic fluid for assessment of fetal lung maturity.
D000653:Amniotic Fluid / Q000378:metabolism*; D001322:Autoanalysis; D002855:Chromatography, Thin Layer; D004798:Enzymes; D005325:Fetal Organ Maturity; D006801:Humans; D007202:Indicators and Reagents; D008168:Lung / Q000196:embryology; D010713:Phosphatidylcholines / Q000032:analysis*; D010715:Phosphatidylglycerols / Q000032:analysis*; D013109:Sphingomyelins / Q000032:analysis*
D004798:Enzymes; D007202:Indicators and Reagents; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D013109:Sphingomyelins