Biomaterial Database

A comparison of acyl-oxyester and acyl-thioester substrates for some lipolytic enzymes. 1979

A J Aarsman, and H van den Bosch

1. A comparison of 2-hexadecanoylthio-ethane-1-phosphocholine and 3-hexadecanoylthio-propane-1-phosphocholine and their oxyester counterparts as substrates for some lipolytic enzymes was made. 2. The critical micelle concentration and the transition temperature of the synthetic substrates were compared with the values for 1-hexadecanoyl-sn-glycero-3-phosphocholine. 3. All above-mentioned compounds were deacylated by lysophospholipases. Phospholipase A2 hydrolyzed only the acyl- sulfur- and oxygenester bond in 2-hexadecanoyl-ethane-1-phosphocholine. 4. Kinetic parameters, Km and V, for hydrolysis of these substrates were determined. Km values for thioester substrates were 5--10 fold lower than for the corresponding oxyesters. Maximal hydrolysis rates were 2--5 times higher for the thioesters. 5. Hydrolysis of thioesters by phospholipase A2, lipase and lysophospholipase was shown to proceed by an S-acyl cleavage mechanism. 6. Beef liver lysophospholipase II was rapidly and stoichiometrically inactivated by diisopropylfluorophosphate and bis(p-nitrophenyl) phosphate. Inactivation by the latter inhibitor showed burst-like kinetics. 7. Attempts to show burst-kinetics during the pre-steady state hydrolysis of 2-hexadecanoylthio-ethane-1-phosphocholine by lysophospholipase II were negative. These results are interpreted to indicated that a step prior to deacylation of the enzyme is rate-determining.

UI	MeSH Term	Description	Entries
D007531	Isoflurophate	A di-isopropyl-fluorophosphate which is an irreversible cholinesterase inhibitor used to investigate the NERVOUS SYSTEM.	DFP,Diisopropylfluorophosphate,Fluostigmine,Bis(1-methylethyl) Phosphorofluoridate,Di-isopropylphosphorofluoridate,Diisopropylphosphofluoridate,Dyflos,Floropryl,Fluorostigmine,Di isopropylphosphorofluoridate
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
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008244	Lysophosphatidylcholines	Derivatives of PHOSPHATIDYLCHOLINES obtained by their partial hydrolysis which removes one of the fatty acid moieties.	Lysolecithin,Lysolecithins,Lysophosphatidylcholine
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009596	Nitrophenols	PHENOLS carrying nitro group substituents.	Nitrophenol
D009943	Organophosphorus Compounds	Organic compounds that contain phosphorus as an integral part of the molecule. Included under this heading is broad array of synthetic compounds that are used as PESTICIDES and DRUGS.	Organophosphorus Compound,Organopyrophosphorus Compound,Organopyrophosphorus Compounds,Compound, Organophosphorus,Compound, Organopyrophosphorus,Compounds, Organophosphorus,Compounds, Organopyrophosphorus
D010179	Pancreas	A nodular organ in the ABDOMEN that contains a mixture of ENDOCRINE GLANDS and EXOCRINE GLANDS. The small endocrine portion consists of the ISLETS OF LANGERHANS secreting a number of hormones into the blood stream. The large exocrine portion (EXOCRINE PANCREAS) is a compound acinar gland that secretes several digestive enzymes into the pancreatic ductal system that empties into the DUODENUM.
D010713	Phosphatidylcholines	Derivatives of PHOSPHATIDIC ACIDS in which the phosphoric acid is bound in ester linkage to a CHOLINE moiety.	Choline Phosphoglycerides,Choline Glycerophospholipids,Phosphatidyl Choline,Phosphatidyl Cholines,Phosphatidylcholine,Choline, Phosphatidyl,Cholines, Phosphatidyl,Glycerophospholipids, Choline,Phosphoglycerides, Choline