Abstract
Extract: Phosphorylcholine cytidyltransferase, the enzyme which catalyzes the transfer of phosphorylcholine to cytidine 5′-triphosphate to form CDP-choline, was studied for the first time in human neonatal lung. The assay of product synthesis was linear for 10–20 min and up to 12 mg protein. The pH optimum was 6–6.5. The Km of CTP was 2.0 × 10−3 M, and the Km of phosphorylcholine was 0.25 × 10−3 M. The true Vmax was 10 nmol CDP-choline/mg protein/10 min. The enzyme was stable under frozen conditions. Oxygen had no apparent affect on enzyme activity.
Speculation: In some tissues, phosphorylcholine cytidyltransferase is possibly the site for a feedback control mechanism of lecithin synthesis. Since there is a relationship between pulmonary lecithin synthesis and neonatal respiratory distress syndrome, purification and characterization of phosphorylcholine cytidyltransferase from human neonatal lung may be of significance.
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Thom, M., Zachman, R. The Enzymes of Lecithin Biosynthesis in Human Neonatal Lungs. IV. Phosphorylcholine Cytidyltransferase. Pediatr Res 9, 201–205 (1975). https://doi.org/10.1203/00006450-197504000-00012
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DOI: https://doi.org/10.1203/00006450-197504000-00012