Isolation and specificity of rat lecithin: Cholesterol acyltransferase: Comparison with the human enzyme using reassembled high-density lipoproteins containing ether analogs of phosphatidylcholine

Henry J. Pownall, Quein Pao, John B. Massey

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

Rat plasma lecithin:cholesterol acyltransferase, a 68 kDa glycoprotein, has been purified 14000-fold by a modification of a procedure used for the human enzyme. The activity of lecithin : cholesteryl acyltransferase in human and rat plasma are the same, although activation of both enzymes by human apolipoprotein A-I is greater than that produced by rat apolipoprotein A-I. Using reassembled high-density lipoproteins composed of human apolipoprotein A-I, phosphatidylcholine ethers and a series of different phosphatidylcholines, the separate effects of molecular species specificity and microenvironment on the rate of cholesteryl ester formation was determined. Substitution of a fluid lipid, 1-palmityl-2-oleyl-sn-glvcero-3-phosphonlcholine. for a solid lipid, 1,2-dipalmityl-sn-glycero-3-phosphorylcholine, produced an 8-fold increase in the activity of all molecular species of phosphatidylcholine. With either solid or fluid lipid environments, the activity decreased as a function of increasing chain length of saturated acyl groups. Addition of one or more double bonds greatly increased the activity of a given saturated homologue. One major difference between the molecular specificity of rat and human lecithin:cholesteryl acyltransferase was that the latter had a two-fold preference for phosphatidylcholines containing arachidonate at the sn-2-position.

Original languageEnglish (US)
Pages (from-to)456-462
Number of pages7
JournalBiochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Volume833
Issue number3
DOIs
StatePublished - Mar 6 1985

Keywords

  • (Rat, Human)
  • Cholesteryl ester
  • High density lipoprotein
  • Lecithin : cholesterol acyltransferase
  • Phosphatidyl ether
  • Substrate specificity

ASJC Scopus subject areas

  • Endocrinology
  • Biophysics
  • Biochemistry

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