title: Effect of zinc deficiency on the biosynthesis of phosphatidylcholine in rat microsomes.
abstract: Phosphatidylcholine is the major lipid of all cellular membranes. Phosphatidylcholine biosynthesis in microsomes involves two enzyme pathways, choline phosphotransferase and phosphatidyl-ethanolamine methyltransferase. The present study was designed to examine the effect of zinc deficiency on these two enzymes. Male, weanling Long-Evans rats were fed a biotin-enriched 20% egg white diet deficient in zinc for 15-45 d. The specific activity (pmol phosphatidylcholine formed/min/mg microsomal protein) of choline phosphotransferase, phsophatidylethanolamine methyltransferase, and phos-phatidyldimethylethanolamine methyltransferase was determined. The latter assay measures the third methylation of phosphatidyl-ethanolamine to phosphatidylcholine. Zinc deficiency resulted in a significant increase over controls in the specific activity of phospha-tidylethanolamine methyltransferase and phosphatidyldimethyl-ethanolamine methyltransferase in liver and spleen microsomes. A significant increase in the picomoles of phosphatidylcholine formed by the choline phosphotransferase pathway occurred in liver microsomes of zinc-deficient animals. In the brain microsomes a significant decrease in specific activity of phosphatidylethanolamine methyltransferase, phosphatidyldimethylethanolamine methyltransferase, and choline phosphotransferase occurred among zinc-deficient ani-mals. These data suggest that zinc deficiency alters the biosynthesis of phosphatidylcholine, the major lipid of cellular membranes.
authors.affiliation: Agricultural Research Service, US Department of Agriculture, School of Medicine, and Grand Forks Human Nutrition Research Center, 58202, Grand Forks, ND.
authors.forename: W E
authors.initials: WE
authors.lastname: Cornatzer
authors.forename: J A
authors.initials: JA
authors.lastname: Haning
authors.forename: J C
authors.initials: JC
authors.lastname: Wallwork
authors.forename: H H
authors.initials: HH
authors.lastname: Sandstead