Hydrolysis of diacylglycerols by lipoprotein lipase.
Enantiomeric diacylglycerols were emulsified, mole for mole, with lyso(1-acyl) lecithin and were hydrolyzed with lipoprotein lipase in NH4Cl-beef serum albumin buffer at pH 8.6 after a brief incubation with delipidated rat serum. The enzyme was prepared from lyophilized and dialyzed bovine skim milk in a 4 percent solution. The course of hydrolysis for each set of enantiomers was determined by gas-liquid chromatography of the masses of the diacylglycerols remaining or monoacylglycerols released in the medium between 0 and 15 min. The majority of sets of sn-1,2- and 2,3-diacylglycerols, including an isotope-labeled true enantiomeric set which was assessed by mass spectrometry, demonstrated preference by the enzyme for lipolysis at position 1 but with less specificity than previously was shown in sn-triacylglycerol hydrolysis. The results preclude the possibility that the predominance of sn-2,3-diacylglycerol intermediates during triacylglycerol hydrolysis is due solely to a preferential breakdown of the 1,2-isomers and reinforce the conclusion that lipoprotein lipase is specific for position 1.
D000818:Animals; D002417:Cattle; D002849:Chromatography, Gas; D004075:Diglycerides / Q000378:metabolism*; D005989:Glycerides / Q000378:metabolism*; D006868:Hydrolysis; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008244:Lysophosphatidylcholines; D013058:Mass Spectrometry; D008892:Milk / Q000201:enzymology; D051381:Rats; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D004075:Diglycerides; D005989:Glycerides; D008244:Lysophosphatidylcholines; D008071:Lipoprotein Lipase