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Plant Physiology 62:348-353 (1978) © 1978 American Society of Plant Biologists Identification of an Acyl Donor in Steryl Ester Biosynthesis by Enzyme Preparations from Spinach LeavesDepartment of Biochemistry and Statewide Air Pollution Research Center, University of California, Riverside, California 92521
A pathway for steryl ester biosynthesis in acetone powder preparations from spinach (Spinacia oleracea L.) leaves has been elucidated; free sterol and 1,2-diglyceride were the substrates. Although animals synthesize cholesteryl esters by three distinct biosynthetic pathways, none of these pathways utilizes 1,2-diglyceride as an acyl donor. Phosphatidylcholine, phosphatidic acid, triglyceride, 1,3-diglyceride, 1-monoglyceride, free fatty acid, and fatty acyl-CoA were not acyl donors for spinach leaf steryl ester biosynthesis in our assay system. The unstable 2 isomer of monoglyceride was not tested. It is possible that 1,2-diglyceride and 2-monoglyceride were both acyl donors for spinach leaf steryl ester biosynthesis. Acyl-labeled phosphatidylcholine and acyl-labeled phosphatidylethanolamine were rapidly degraded by acetone powder preparations to 1,2-diglyceride via phosphatidic acid. The 1,2-diglycerides were slowly metabolized to monoglycerides, triglycerides, free fatty acids, and steryl esters. The monoglycerides were rapidly degraded to free fatty acids and glycerol.
1 Supported by a predoctoral National Science Foundation Traineeship. 2 Present address: Biomedical Sciences Division, Lawrence Livermore Laboratory, University of California Livermore, California 94550. This article has been cited by other articles:
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