Acetyl-acyl carrier protein is not a major intermediate in fatty acid biosynthesis in spinach.
The extent to which acetyl-acyl carrier protein (acetyl-ACP) is an intermediate in fatty acid biosynthesis was examined. Acetyl-ACP was the least effective primer of fatty acid synthesis by spinach extracts when compared to acetyl-CoA, butyryl-ACP or hexanoyl-ACP. Furthermore, the rate of acetyl-ACP-primed fatty acid synthesis was inhibited significantly by cerulenin, indicating that the slow utilization of acetyl-ACP was predominantly by 3-oxoacyl-ACP synthase I. In light-incubated isolated chloroplasts with high rates of fatty acid synthesis (greater than 800 nmol.h-1.mg chlorophyll-1), the rate of acetyl-ACP metabolism was at least 10-30-fold slower than the rate of butyryl-ACP metabolism. The relatively slow metabolism of acetyl-ACP provided in situ evidence that (a) butyryl-ACP was formed principally from condensation of malonyl-ACP with acetyl-CoA and (b) acetyl-ACP was a minor participant in fatty acid biosynthesis.
Chemistry Department, Miami University, Oxford, OH 45056.
J G
JG
Jaworski
D
D
Post-Beittenmiller
J B
JB
Ohlrogge
D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000213:Acyl Carrier Protein / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis*; D010944:Plants / Q000378:metabolism*; D014675:Vegetables
D000213:Acyl Carrier Protein; D005227:Fatty Acids; D000105:Acetyl Coenzyme A