[8] Lysophosphatidylcholine acyltransferase

This chapter discusses lysophosphatidylcholine acyltransferase. Lyso-PC:acyl-CoA acyltransferase activity is detected in various mammalian tissues, bacteria, protozoa, and plants. The transfer of acyl groups from acyl-CoA to 1-acylglycerophosphocholine (1-acyl-GPC) is catalyzed by 1-acyl-GPC: acyl-CoA acyltransferase, whereas transfer of fatty acids to 2-acyl-GPC is catalyzed by 2-acyl-GPC:acyl-CoA acyltransferase. These two reactions are carried out by separate enzymes. Most of the studies on acyltransferase focus on the acylation of l-acyl-GPC; limited information is available on the acylation of 2-acyl-GPC. This chapter describes procedures for the assaying of 1-acyl-GPC: acyl-CoA acyltransferase. Enzyme activity is determined by the incorporation of a radiolabeled acyl group into 1-acyl-GPC to form 1,2-diacyl-GPC. The radiolabeled product is isolated from the substrate by phase separation followed by thin-layer chromatography. The characteristics and kinetics of enzyme is discussed in the chapter. The data obtained from the spectrophotometric assay must be confirmed by a more specific assay.