Biomaterial Database

Interfacial activation, lysophospholipase and transacylase activity of group VI Ca2+-independent phospholipase A2. 1998

Y C Lio, and E A Dennis

Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0601, USA.

The Group VI 80-kDa Ca2+-independent phospholipase A2 (iPLA2) has been purified from murine P388D1 macrophages and Chinese hamster ovary (CHO) cells. The amino acid sequence of the iPLA2 has been determined and shown to contain a lipase consensus sequence and eight ankyrin repeats, which makes it distinct from Group I-V PLA2s. This enzyme appears to play a key role in mediating basal phospholipid remodeling. We now report that the Group VI iPLA2 displays interfacial activation toward short chain phospholipids, 1-octanoyl-2-heptanoyl-sn-glycero-3-phosphocholine, 1,2-diheptanoyl-sn-glycero-3-phosphocholine, and 1,2-dihexanoyl-sn-glycero-3-phosphocholine micelles. ATP protects the iPLA2 from a loss in activity as a result of prolonged incubation during the assay. Hence higher enzyme activity is observed in the presence than in the absence of ATP. Similar protection was obtained with glycerol. In addition, the iPLA2 exhibits multiple activities which are strongly dependent on substrate presentation. The lysophospholipase activity of this enzyme was diminished by Triton X-100 and stimulated by glycerol. With the combination of 50 microM Triton X-100 and 50% glycerol, the enzyme's lysophospholipase activity achieved equivalent activity to its PLA2 activity. The iPLA2 displayed both lysophospholipid/transacylase and phospholipid/transacylase activity, supporting the conclusion that the mechanism of action of iPLA2 proceeds through an acyl-enzyme intermediate as proposed for the Group IV cPLA2.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008049	Lipase	An enzyme of the hydrolase class that catalyzes the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. It is produced by glands on the tongue and by the pancreas and initiates the digestion of dietary fats. (From Dorland, 27th ed) EC 3.1.1.3.	Triacylglycerol Lipase,Tributyrinase,Triglyceride Lipase,Acid Lipase,Acid Lipase A,Acid Lipase B,Acid Lipase I,Acid Lipase II,Exolipase,Monoester Lipase,Triacylglycerol Hydrolase,Triglyceridase,Triolean Hydrolase,Hydrolase, Triacylglycerol,Hydrolase, Triolean,Lipase A, Acid,Lipase B, Acid,Lipase I, Acid,Lipase II, Acid,Lipase, Acid,Lipase, Monoester,Lipase, Triglyceride
D008245	Lysophospholipase	An enzyme that catalyzes the hydrolysis of a single fatty acid ester bond in lysoglycerophosphatidates with the formation of glyceryl phosphatidates and a fatty acid. EC 3.1.1.5.	Lecithinase B,Lysolecithinase,Phospholipase B,Lysolecithin-Lysolecithin Acyltransferase,Lysophospholipase A,Lysophospholipase A1,Lysophospholipase C,Lysophospholipase L2,Acyltransferase, Lysolecithin-Lysolecithin,L2, Lysophospholipase,Lysolecithin Lysolecithin Acyltransferase
D008264	Macrophages	The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)	Bone Marrow-Derived Macrophages,Monocyte-Derived Macrophages,Macrophage,Macrophages, Monocyte-Derived,Bone Marrow Derived Macrophages,Bone Marrow-Derived Macrophage,Macrophage, Bone Marrow-Derived,Macrophage, Monocyte-Derived,Macrophages, Bone Marrow-Derived,Macrophages, Monocyte Derived,Monocyte Derived Macrophages,Monocyte-Derived Macrophage
D009097	Multienzyme Complexes	Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES.	Complexes, Multienzyme
D010741	Phospholipases A	Phospholipases that hydrolyze one of the acyl groups of phosphoglycerides or glycerophosphatidates.
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D005990	Glycerol	A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, or sweetening agent.	1,2,3-Propanetriol,Glycerin,1,2,3-Trihydroxypropane,Glycerine