Factors influencing the in vitro activity of diacylglycerol acyltransferase from bovine mammary gland and liver towards butyryl-CoA and palmitoyl-CoA.

1. Factors affecting the incorporation of butyrate relative to palmitate into the sn-3 position of triacylglycerol by the diacylglycerol acyltransferase from bovine mammary gland and liver was studied in vitro. 2. Butyrate incorporation from butyryl-CoA in the presence of palmitoyl-CoA was favoured by a high concentration of butyryl-CoA and by the presence of a long-chain acyl-CoA binding protein such as bovine serum albumin. 3. The relative activity of the enzyme from both tissues towards butyryl-CoA and palmitoyl-CoA was independent of the concentration of membrane-bound 1,2-dipalmitoylglycerol. 4. The significance of these results in relation to the unique presence of short-chain acids in ruminant milk triacylglycerols is discussed.