Deacylation and reacylation of phosphatidylcholines by liver homogenates from chick embryos.

Liver homogenates from 13, 17 and 21 day-old chick embryos were incubated with phosphatidylcholine and lysophosphatidylcholine labeled with fatty acids to study deacylation and reacylation reactions of phosphatidylcholines during development. By using phosphatidylcholines labeled with palmitic or linoleic acids in position 1 or 2, respectively, phospholipase A2 activity was detected. By using lysophosphatidylcholine labeled with palmitic acid in position 1, preferential acylation with araquidonic acid was demonstrated. In agreement with this data, the incubation of dienoic phosphatidylcholines labeled with palmitic acid in position 1, with the liver homogenates, gave rise to labeled tetraenoic phosphatidylcholines. The extent of both deacylation and reacylation of the phosphatidylcholine molecule in position 2 by liver homogenates from chick embryos, decreased during development.