出版社：American Society for Biochemistry and Molecular Biology
摘要：The percentage of saturated cholesteryl esters (CEs) synthesized by human LCAT is several times higher than expected from the sn -2 acyl composition of plasma phosphatidylcholine (PC), whereas the synthesis of 20:4 CE and 22:6 CE is much lower than expected. To explain these discrepancies, we proposed that LCAT transfers some saturated fatty acids from the sn -1 position of PC species that contain 20:4 or 22:6 at sn -2. The present studies provide in vivo evidence for this hypothesis. We determined the composition and synthesis of CE species in plasma of volunteers before and after a 6 week dietary supplementation with docosahexaenoic acid (22:6; DHA). In addition to an increase in the DHA content of all plasma lipids, there was a significant (+12%; P sn -2 of PC. The increase of DHA in CE was much lower than its increase at sn -2 of PC. Ex vivo synthesis of CE species in plasma showed a significant (+24%; P sn -2 of PC. These results show that the positional specificity of human LCAT is altered when the concentration of 16:0-22:6 PC is increased by DHA supplementation.
