Muma NA, Rowell PP. A sensitive and specific radioenzymatic assay for the simultaneous determination of choline and phosphatidylcholine.
J Neurosci Methods 1985;
12:249-57. [PMID:
3982073 DOI:
10.1016/0165-0270(85)90008-1]
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Abstract
A radioenzymatic procedure for the simultaneous measurement of picomol quantities of phosphatidylcholine and choline is described. Phospholipase-D from Streptomyces chromofuscus hydrolyzes phosphatidylcholine to choline and phosphatidic acid. Choline kinase in the presence of [32P]ATP phosphorylates the choline to form [32P]phosphorylcholine. The phosphorylcholine, isolated by ion exchange chromatography, is measured by scintillation spectroscopy. Using a chloroform: methanol separation, phosphatidylcholine and choline can be measured from the same sample. Different sources of phospholipase-D were compared for their ability to hydrolyze phosphatidylcholine to choline and phosphatidic acid. Phospholipase-D from Streptomyces chromofuscus was found to result in almost complete hydrolysis. As a measure of specificity, lysophosphatidylcholine and sphingomyelin were assayed using this method and were found to result in, at most, only 2% of the amount of phosphorylcholine produced compared to phosphatidylcholine. This procedure allows for the simultaneous measurement of choline and phosphatidylcholine in brain and serum samples with a very high degree of sensitivity and specificity.
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