SOME PROPERTIES OF DIACYLGLYCEROL ACYLTRANSFERASE IN A PARTCULATE FRACTION FROM MATURING SAFFLOWER SEEDS

Article abstract of DOI:10.1016/0031-9422(82)83010-0

The activity of diacylglycerol acyltransferase of a subcellular particulate fraction from maturing safflower seeds was remarkably stimulated by the addition of 1,2-diacylglycerols which were previously emulsified in a gelatin solution by sonication.Metal ions were inhibitory to the reaction.Deoxycholate and diisopropyl fluorophosphate were the most effective inhibitors.Sulfhydryl groups seemed to be of limited significance in the enzyme.Both 1,2-dioleoyl-sn-glycerol and 2,3-dioleoyl-sn-glycerol were good substrates of diacylglycerol acyltransferase, but the 1,3-isomer did not serve as an acyl acceptor.The enzyme showed broad specificity for synthetic rac-1,2-diacylglycerols containing various fatty acids.However, rac-1,2-diecetylglycerol and rac-1,2-dibutylglycerol, which are soluble in water, were ineffective.The enzyme exhibited no significant specificity for saturated and unsaturated fatty acyl-CoA thioesters as acyl donors.This suggests that the fatty acid composition at the 3-position of the glycerol molecule of safflower triacylglycerols may depend on the composition of the endogenous acyl-CoA pool.Key Word Index - Carthamus tinctorius; Compositae; safflower; seeds; triacylglycerol synthesis; diacylglycerol acyltransferase.