Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.34 (lipoprotein lipase)
7,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Once brain ischemia was induced in the gerbil cerebral fronto-parietal cortex, serial changes occurred in energy metabolites and various lipids. The amounts of inositol-containing phospholipids began to decrease immediately after energy failure, followed by an increase in the amount of 1,2-diacylglycerol with a subsequent liberation of arachidonic acid and other free fatty acids. The fatty acid compositions of inositol-containing phospholipids, of 1,2-diacylglycerols produced by ischemia, and of free fatty acids liberated during ischemia were quite similar. The amount of stearic acid liberated was much larger than that of arachidonic acid between 30 s and 1 min of ischemia. On the other hand, there was no significant decrease in the amount of the other phospholipids except for phosphatidic acid. Furthermore, there was also no change in the fatty acid composition of phosphatidylcholine or phosphatidylethanolamine throughout 15 min of ischemia. The amount of cytidine-monophosphate reached a peak (36.7 nmol/g wet wt) at 2 min of ischemia. These results indicated that arachidonic acid was predominantly liberated from inositol-containing phospholipids by phospholipase C, and by the diglyceride lipase and monoglyceride lipase system rather than from phosphatidylcholine or phosphatidylethanolamine by phospholipase A2 or plasmalogenase or choline phosphotransferase during the early period of ischemia.
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PMID:Mechanism of arachidonic acid liberation during ischemia in gerbil cerebral cortex. 379 19

Some hormonal factors, possibly involved in the proliferation and differentiation of adipose precursor cells in vivo, have been characterized in vitro using different preadipocyte cell lines established from rodent adipose tissue. The process of adipose conversion has also been studied using these cell lines; in this process, stem cells (adipoblasts) were committed at any cell division during the growth phase. At confluence, committed cells (preadipocytes) underwent a limited number of mitoses and differentiated into adipose cells, whereas the uncommitted cells remained as stem cells in the cell population. This stochastic model could be extended to the development of rat adipose tissue in vivo. The study of adipose conversion showed the early emergence of lipoprotein lipase (LPL) and monoglyceride lipase (MGL). LPL activity appeared in the cells before any triglyceride accumulation. In contrast, this accumulation seemed dependent upon the emergence of glycerol-3-phosphate dehydrogenase. In vitro experiments clearly established that LPL-containing (differentiating) cells underwent postconfluent mitoses. This limited proliferation was in agreement with previous data obtained in vivo and indicates that only triglyceride-containing (mature) cells could not divide.
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PMID:[Lipoprotein lipase and adipocyte differentiation]. 388 22

1. Combined guinea-pig cortex and cerebellum was shown to contain triglyceride lipase, diglyceride lipase and monoglyceride lipase, which were assayed by the release of [1-(14)C]palmitate from [1-(14)C]palmitoylglycerol esters. Triglyceride lipase and diglyceride lipase were found in all particulate fractions. 2. With osmotically ruptured synaptosomes the rates of release of palmitate from glyceryl tripalmitate and glyceryl dipalmitate were 7-25mumol/h per g of protein and 0.18-0.69mmol/h per g of protein respectively. The logarithm of the rate of hydrolysis of glyceryl monopalmitate increased linearly with the logarithm of protein concentration. The pH optima of triglyceride lipase and diglyceride lipase were between 7 and 8. The pH optimum for monoglyceride lipase was approx. 8. 3. Triglyceride lipase and diglyceride lipase of osmotically ruptured synaptosomes were stimulated by noradrenaline, 5-hydroxytryptamine and adrenaline. Triglyceride lipase of isolated synaptic membranes was stimulated by 0.01-1mm-noradrenaline. Aging of membranes at 0 degrees C decreased activity, which could still be stimulated by noradrenaline. Diglyceride lipase of isolated membranes was stimulated by 1mum-1mm-noradrenaline. The activity of triglyceride lipase in isolated synaptic vesicles was diminished by 1mm-5-hydroxytryptamine.
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PMID:Glyceride lipases in nerve endings of guinea-pig brain and their stimulation by noradrenaline, 5-hydroxytryptamine and adrenaline. 472 38

A monoglyceride lipase was partly purified from extracts of rat adipose tissue by ammonium sulfate fractionation, alcohol precipitation, and lyophilization, or by ammonium sulfate fractionation, sodium deoxycholate treatment, and a second ammonium sulfate fractionation. Partial purification and heat denaturation showed the lipase to be different from tributyrinase and from an enzyme(s) which hydrolyzes diglycerides and triglycerides. Although the best preparations hydrolyzed monobutyrin this activity decreased with purification, indicating that the enzyme acts on insoluble substrates and is therefore a lipase and not an esterase. Further-more, classification of the enzyme as a lipase is consistent also with its behavior with inhibitors, since low concentrations of esterase inhibitors, e.g., fluoride, sodium deoxycholate, and physostigmine did not inhibit lipolytic activity. Inhibition studies with EDTA, sodium pyrophosphate, protamine, and fluoride showed that the enzyme differs from clearing factor lipase. The enzyme catalyzed hydrolysis of monostearin in the pH range 6.3-9.0, with a maximum at 7.4-7.6.
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PMID:Partial purification of monoglyceride lipase from adipose tissue. 594 37

Differentiation of 3T3-L1 fibroblasts to adipocyte-like cells was accompanied by a 19-fold increase in neutral triglyceride lipase activity, a 12-fold increase in diglyceride lipase activity, a 10-fold increase in monoglyceride lipase activity, and a 280-fold increase in cholesterol esterase activity. In contrast, acid acylhydrolase activities did not increase during differentiation. The rate of glycerol release from unstimulated intact cells increased by more than 1 order of magnitude upon differentiation. Isoproterenol (1 microM) and 1-methyl-3-isobutylxanthine (0.1 mM) further stimulated this rate of glycerol release 3-fold. The neutral triglyceride lipase activity in cell-free preparations of differentiated cells was activated 105% by cyclic AMP-dependent protein kinase. Neutral cholesterol esterase, diglyceride lipase, and monoglyceride lipase were also activated (117%, 10%, and 37+, respectively) by cyclic AMP-dependent protein kinase. In contrast, protein kinase had no effect on any of the four lysosomal acid acylhydrolase activities. Thus, hormone-sensitive lipase, the most characteristic and functionally important enzyme of adipose tissue, has been characterized in differentiated 3T3-L1 cells. The 3T3-L1 cell should be a valuable model system in which to study regulation of hormone-sensitive lipase, particularly its long-term regulation.
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PMID:Hormone-sensitive lipase in differentiated 3T3-L1 cells and its activation by cyclic AMP-dependent protein kinase. 626 67

RHC 80267 inhibits diglyceride lipase activity in microsomes from canine platelets (1). Chau and Tai (2) reported that RHC 80267 prevents the transient accumulation of monoglyceride in thrombin-stimulated human platelets, while leaving arachidonate release unimpaired. In contrast, we find that while the drug inhibits both diglyceride lipase (I50 = 15 microM) and monoglyceride lipase (I50 = 11 microM) activities in platelet microsomes, it is ineffective when added to intact platelets. The transient intermediates in the diglyceride lipase pathway, 1,2-diglyceride and 2-monoglyceride, both accumulated after thrombin stimulation of intact platelets treated with RHC 80267, and arachidonate release was not inhibited. We conclude that RHC 80267 cannot be used to evaluate the diglyceride lipase pathway in intact platelets.
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PMID:RHC 80267 does not inhibit the diglyceride lipase pathway in intact platelets. 641 55

We have measured the hydrolysis of tri-, di- and monoacylglycerols and of phosphatidylcholine in the lung and have quantitated the incorporation of glyceride and phospholipid fatty acids into lung lipids. Lipolytic activity was studied in the isolated, ventilated, rat lung perfused for 100 min in a recycling system with Krebs-Ringer bicarbonate buffer containing 3% bovine serum albumin, 5.6 mM glucose, and the lipid emulsions. Triacylglycerols were hydrolyzed at significantly (P less than 0.05) lower rates than partial acylglycerols. Hydrolysis of di- and triacylglycerols was significantly lower in lungs of animals given i.v. heparin 60 min prior to death. The incorporation of fatty acids released from acylglycerols was greater into lung neutral fats than into lung phospholipids. Phosphatidylcholine was also hydrolyzed in the isolated perfused lung. The data show that (a) neutral glycerides and phospholipids are hydrolyzed in the isolated, ventilated, perfused rat lung; (b) the hydrolysis of tri- and diacylglycerols is markedly inhibited in lungs isolated from rats given heparin (100 U/kg) 1 h prior to death, whereas the hydrolysis of monoacylglycerol is unaffected by heparin administration, suggesting that tri- and diacylglycerols are hydrolyzed by endothelial lipoprotein lipase, whereas hydrolysis of monoacylglycerol is catalyzed by a separate monoacylglycerol lipase; (c) free fatty acids released by lipoprotein lipase are used by the lung for metabolic needs.
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PMID:Hydrolysis of neutral lipids and phospholipids in the isolated, perfused rat lung. 646 97

Mobilization of triacylglycerol stored in heart cells is accomplished by the combined action of lysosomal (acid) lipase and microsomal monoacylglycerol lipase or carboxylesterase. Non(heparin)-releasable neutral or alkaline lipase is similar to non(readily)-releasable lipoprotein lipase (LPL). The enzyme is mainly localized extracellularly. Non(readily)-releasable LPL probably represents LPL in caveola or vacuolae of vascular endothelium and/or LPL on myocardial interstitium. It contributes to the uptake of lipoprotein constituents in heart cells. Glycerol, an endproduct of lipolysis, is not a reliable marker for the net mobilization of lipid stored in heart cells. It is formed both intra- and extracellularly, and does not reflect the rate of oxidation of part of free fatty acids formed.
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PMID:Localization and function of myocardial lipolysis. 647 80

Mono- and diacylglycerol lipases are differentially inhibited by heparin. No other glycosaminoglycan resembles heparin in this respect. Mono- and diacylglycerol lipases can be separated by heparin Sepharose affinity chromatography. Diacylglycerol lipase was completely retained on a heparin--Sepharose column and was eluted with either 0.5 M NaCl or 2-5 mg/ml heparin, whereas monoacylglycerol lipase was recovered in the washings. Adenosine phosphates markedly affected the activity of diacylglycerol lipase in a concentration dependent manner. ATP was the most potent inhibitor followed by ADP. AMP had no effect and cAMP slightly stimulated the diacylglycerol lipase.
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PMID:Separation of bovine brain mono- and diacylglycerol lipases by heparin sepharose affinity chromatography. 647 59

Acyl-CoA:1-acylglycerophosphate acyltransferase activity was found in porcine erythrocyte membranes. However, the membrane preparations did not catalyze the acylation of either 2-acylglycerophosphate or 2-acylglycerophosphocholine. The 1-acylglycerophosphate acyltransferase and the known acyl-CoA:1-acylglycerophosphocholine acyltransferase systems differ in their specificities for acyl-CoAs and in their stabilities to detergents. Diacylglycerol lipase and monoacylglycerol lipase activities were also detected in porcine erythrocytes. These two activities appear to be catalyzed by different enzymes inasmuch as diacylglycerol lipase but not monoacylglycerol lipase was completely inhibited by divalent cations. The diacylglycerol lipase was relatively specific for the 1-position yielding 2-acylglycerol. The monoacylglycerol lipase hydrolyzed 1-acylglycerol and 2-acylglycerol at comparable rates. Phosphatidic acid was dephosphorylated to form 1,2-diacylglycerol but the acyl groups of phosphatidate were not hydrolyzed significantly by the erythrocyte membranes. Thus, the origin of 1-acylglycerophosphate, a substrate for the newly described enzyme, acyl-CoA:1-acylglycerophosphate acyltransferase, in mature erythrocyte could not be ascribed to action of diacylglycerol lipase, glycerophosphate acyltransferase, or phosphatidate-specific phospholipase A. 1-Acylglycerophosphate may be supplied extracellularly or the 1-acylglycerophosphate acyltransferase activity in erythrocytes may be a remnant of de novo phosphatidate synthesizing system of reticulocytes.
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PMID:Properties of acyl-coenzyme A:1-acylglycerophosphate acyltransferase and lipases in porcine erythrocyte membranes. 649 29


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