Selective Transfer of Cyclopropane Acids by Acyl Coenzyme A:Phospholipid Acyltransferases
Harumi Okuyama 1, William E. M. Lands 1, William W. Christie 2, and Frank D. Gunstone 2
From the
1 From the Department of Biological Chemistry, the University of Michigan, Ann Arbor, Michigan 48104
2 From the Chemistry Department, the University of St. Andrews, Scotland
Coenzyme A thiol esters of the complete series of positional isomers of cis-methylene octadecanoic acid were synthesized. Their activities as substrates for acyl-CoA: phospholipid acyltransferases of rat liver microsomes were determined with positional isomers of acylglycerophosphoryl choline and acylglycerophosphoryl ethanolamine as acceptors. The results showed that the acyltransferases discriminated between the acyl-CoA isomers in quite different ways. Certain acyl-CoA esters were transferred at much different rates with different acylglycerophospholipid acceptors, suggesting that different enzymes were acting with the different acceptors. Comparison of the rates of cis-cyclopropane acid derivatives and cis-octadecenoic acid derivatives showed that the presence of 
bonds in the acyl residue is not an important factor for the enzyme or enzymes transferring cis-acyl groups to the 1 position of acylglycerophospholipids. On the other hand, the presence of a bond can cause higher or lower transfer rates to the 2-hydroxyl depending upon the location of the cis-functional group along the acyl chain.
Submitted on August 11, 1969
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