Bovine brain diacylglycerol lipase: substrate specificity and activation by cyclic AMP-dependent protein kinase.
Diacylglycerol lipase (EC 3.1.1.3) was purified from bovine brain microsomes using multiple column chromatographic techniques. The purified enzyme migrates as a single band on SDS-PAGE and has an apparent molecular weight of 27 kDa. Substrate specificity experiments using mixed molecular species of 1,2-diacyl-sn-glycerols indicate that low concentrations of Ca(2+) and Mg(2+) have no direct effect on enzymic activity and 1,2-diacyl-sn-glycerols are the preferred substrate over 1,3-diacyl-sn-glycerols. The enzyme hydrolyzes stearate in preference to palmitate from the sn-1 position of 1,2-diacyl-sn-glycerols. 1-O-Alkyl-2-acyl-sn-glycerols are not a substrate for the purified enzyme. The native enzyme had a V (max) value of 616 nmol/min mg protein. Phosphorylation by cAMP-dependent protein kinase resulted in a threefold increase in catalytic throughput (V (max) = 1,900 nmol/min mg protein). The substrate specificity and catalytic properties of the bovine brain diacylglycerol lipase suggest that diacylglycerol lipase may regulate protein kinase C activity and 2-arachidonoyl-sn-glycerol levels by rapidly altering the intracellular concentration of diacylglycerols.
Rosenberger
Thad A
TA
Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, 501 North Columbia Road, Grand Forks, ND 58203, USA. trosenberger@medicine.nodak.edu
Farooqui
Akhlaq A
AA
Horrocks
Lloyd A
LA
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D002849:Chromatography, Gas; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005227:Fatty Acids / Q000378:metabolism; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000378:metabolism*; D013379:Substrate Specificity
D005227:Fatty Acids; D017868:Cyclic AMP-Dependent Protein Kinases; D008071:Lipoprotein Lipase