Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.79 (hormone-sensitive lipase)
 2,163 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In present study interactions of some adrenergic drugs with the binding of 3H-norepinephrine (NE) and response of some enzymatic systems in the heart of rats with pharmacological hyperthyroidism have been investigated. Binding of NE to cardiac particles was inhibited by isoproterenol, propranolol and in lower concentrations by another beta-blocking drug trimepranol both in control and hyperthyroid hearts in the same degree. However, after addition of nonradioactive norepinephrine (10(-3) M) the degree of displacement was lower in hyperthyroid than in euthyroid group. Activity of adenylate cyclase was lower in hyperthyroid cardiac particles. This difference remained preserved after stimulation by norepinephrine or NaF. The activities of hormone-sensitive lipase and lipoprotein lipase were increased in preparation of hyperthyroid hearts. The phosphorylase "a" activity was also increased in hyperthyroid cardiac particles. There was no change in cardiac adrenergic binding sites properties in hyperthyroidism with the exception of less displacement of NE by nonlabelled hormone. The results indicate that the increased lipolytic and phosphorylase "a" activities in hyperthyroid hearts are not necessarily linked to elevated activity of adenylate cyclase.
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PMID:Adrenergic binding sites and enzyme activities in the heart of hyperthyroid rats. 0 59

Lipolytic activity was measured under different conditions in isolated fat cells and homogenates of human adipose tissue of the greater omentum. It was demonstrated that lipolysis took place in isolated fat cells at an optimum pH of 7.4 and was markedly stimulated by noradrenaline, but not by blood serum. By contrast lipolysis was significantly stimulated by blood serum, but not by noradrenaline, in homogenates of adipose tissue. Serum-stimulated lipolysis exhibited optimum activity at pH 8 and was inhibited by 1M sodium chloride. It is concluded that lipolytic activity in isolated fat cells can mainly be ascribed to the action of hormone-sensitive lipase, whereas lipolysis in homogenates of adipose tissue in the presence of serum is mostly regulated by lipoprotein lipase.
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PMID:[Lipolysis in human adipose tissue (author's transl)]. 0 90

Hormone-sensitive lipase and cholesterol ester hydrolase of chicken adipose tissue were markedly activated by adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase (on the average, 235 to 275%; occasionally as much as 1000%). Diglyceride and monoglyceride hydrolases were also activated, but to a lesser extent (60 to 87%). The activation of all four hydrolases was inhibited by protein kinase inhibitor and reversed by the addition of exogenous protein kinase. Following activation by cAMP-dependent protein kinase, all four hydrolases were deactivated in a Mg2+-dependent reaction and then reactivated to or near initial levels on incubation with cAMP and Mg2+-ATP. The reversible deactivation is assumed to reflect activity of one or more protein phosphatases. The maximum activation obtainable for the four hydrolases decreased when the tissue had been previously exposed to glucagon, indicating that the glucagon-induced activation was probably similar to or identical with the activation demonstrated in cell-free preparations. The pH optima for the four hydrolase activities were similar (7.13 to 7.38). Although the absolute activities and relative degrees of kinase activation differed according to the particular emulsified substrates used, the results do not rule out the possibility that all four hydrolase activities are referable to a single hormone-sensitive hydrolase. Hormone-sensitive acyl hydrolases were separated from lipoprotein lipase by heparin-Sepharose affinity chromatography. Lipoprotein lipase was active against triolein, diolein, and monoolein, but not cholesterol oleate. Incubation of lipoprotein lipase with exogenous protein kinase, cAMP, and Mg2+ATP had no effect on any of the three hydrolase activities. Lipoprotein lipase was further purified to homogeneity and used to prepare antiserum in rabbits. The immunoglobin G fraction from these antisera completely inhibited lipoprotein lipase eluted from heparin-Sepharose columns. However, the hormone-sensitive hydrolase activities (not retained on heparin-Sepharose affinity chromatography) were not inhibited by anti-lipoprotein lipase immunoglobin G, and anti-lopoprotein lipase immunoglobin G did not affect the activation process in crude fractions. Thus, hormone-sensitive lipase and lipoprotein lipase, functionally distinct enzymes, have been physically resolved and immunochemically distinguished. Apparently lipoprotein lipase activity is not regulated, at least directly, by cAMP-dependent protein kinase.
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PMID:Triglyceride, diglyceride, monoglyceride, and cholesterol ester hydrolases in chicken adipose tissue activated by adenosine 3':5'-Monophosphate-dependent protein kinase. Chromatographic resolution and immunochemical differentiation from lipoprotein lipase. 0 45

A triglyceride lipase was extracted from defatted pig adipose tissue powder with dilute ammonia and purified about 230-fold by a combination of ammonium sulfate fractionation, heparin-Sepharose 4B, DEAE-cellulose, and Sephadex G-150 column chromatographies and isoelectrofocusing electrophoresis. The enzyme was distinguishable in physical and kinetic properties from the two previously defined lipases in adipose tissue, lipoprotein lipase, and hormone-sensitive lipase. The purified enzyme was fully active in the absence of serum lipoprotein and was not stimulated by adenosine 3':5'-monophosphate-dependent protein kinase. In marked contrast to the already defined lipases, the enzyme was strongly inhibited by serum albumin. The enzyme had a molecular weigt of about 43,000, a pI of 5.2, and pH optimum of 7.0. The enzyme hydrolyzed triolein to oleic acid and glycerol, and did not exhibit esterase activity. The apparent Km for triolein was 0.05 mM. Physiological roles of this new species of lipase remained to be explored.
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PMID:Partial purification and characterization of a triglyceride lipase from pig adipose tissue. 1 Feb 95

A new assay procedure for triglyceride lipase [EC 3.1.1.3] was developed in which radioactive triolein was dissolved in ethanol and directly added to the reaction mixture in the absence of serum and albumin. In the rat adipose tissue there appeared to be a triglyceride lipase measurable with this assay in addition to the two previously defined lipases, lipoprotein lipase [EC 3.1.1.34] and hormone-sensitive lipase. The enzyme was active in the absence of serum and was strongly inhibited by albumin. The molecular weight was estimated to be about 42,000. Adenosine 3',5'-monophosphate-dependent protein kinase [EC 2.7.1.27] was unable to activate the enzyme. The three species of lipases mentioned above behaved differently upon chromatography on a Sepharose 4B column, and were distinguishable from each other in their physical and kinetic properties. The physiological roles of the new species of lipase remain to be explored.
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PMID:Studies on triglyceride lipases from rat adipose tissue. 1 45

Lipolysis in human adipose tissue was measured as glycerol release in isolated fat cells and in adipose tissue homogenates. In isolated fat cells lipolysis proceeded optimally at pH 7.4, was stimulated 3.5 fold by noradrenaline and was not influenced by serum or protamine. In adipose tissue homogenates lipolysis was stimulated 4 fold by serum. Serum-stimulated lipolytic activity was optimal at pH 8.0, was inhibited by 1 M sodium chloride and protamine and was not influenced by noradrenaline. Lipolytic activity in isolated fat cells is ascribed on the basis of these observations mainly to the action of hormone-sensitive lipase. whereas lipolysis in adipose tissue homogenates in the presence of serum seems to be regulated by lipoprotein lipase. Thus, the lipolytic processes involved in the mobilization of triglycerides from adipose tissue and in the uptake or triglycerides into adipose tissue can be assessed separately, using the two described methods. The re-esterification of FFA, the second pathway in the mobilization of triglycerides, has also been investigated.
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PMID:[Pathophysiology of lipolysis in human adipose tissue (author's transl)]. 2 89

A convenient method of measuring initial rates of free fatty acid efflux from isolated adipocytes during triglyceride breakdown by hormone-sensitive lipase is described. The procedure is based on the dissociation of protons from carboxyl groups of free fatty acids. A recording pH meter is used to monitor H+ concentration in the medium continuously as an index of free fatty acid release. A stoichiometric relationship was demonstrated between proton release and extracellular free fatty acid concentration as determined by the 63Ni radioassay method of Ho (1970. Anal. Biochem. 36: 105-113). An acid pH (6.8) caused a reduction in proton release, which was immediately and completely reversed by raising the pH to 7.4.
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PMID:pH as an indicator of free fatty acid release from adipocytes. 2 32

Carbenoxolone slightly but significantly decreased the release of FFA from rat epididymal fat pads. The antilipolytic action of carbenoxolone was not blocked by 10(-3)M 3-isobutyl-1-methylxanthine, a potent inhibitor of phosphodiesterase. The findings suggest that carbenoxolone exerts its antilipolytic activity by acting on adenylate cyclase, thereby decreasing cyclic AMP concentrations and the activity of the hormone-sensitive lipase in adipose tissue.
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PMID:Effect of carbenoxolone on lipolysis in rat adipose tissue. 2 44

Some physiologic aspects of the mobilization and fate of free fatty acids are reviewed. The molecular mechanism of the activation of hormone-sensitive lipase in adipose tissue is then discussed. Recent evidence established that hormone-sensitive lipase, concerned with fat mobilization, is both functionally and immunochemically distinct from lipoprotein lipase, concerned with uptake of plasma triglycerides. Lipoprotein lipase activity is not altered by cyclic AMP-dependent protein kinase. The latter enzyme enhances not only triglyceride hydrolase but also monoglyceride, diglyceride and cholesterol ester hydrolase activities in chicken adipose tissue. Finally, it is shown that the activation of all four acyl hydrolases is reversible, the deactivation being magnesium-dependent. Protein phosphatase fractions from heart and liver active against phosphorylase a can reversibly deactivate adipose tissue hormone-sensitive lipase, implying a low degree of substrate specificity for lipase phosphatase.
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PMID:Hormone-sensitive lipase of adipose tissue. 6 71

1. Lipolysis has been estimated by measuring the release of glycerol in isolated adipose tissue cells obtained from women in early prognancy, late pregnancy and 1 - 3 days post partum and from non-pregnant women. 2. Adipocytes of women at the end of pregnancy exhibited higher rates of lipolysis in response to adrenaline (1.5 - 15 muM) plus phentolamine (13 muM) than those of non-pregnant women or those in early pregnancy. 3. Lipolysis in response to adrenaline plus phentolamine in fat cells from women 1 - 3 days post partum was reduced compared to that at the end of gestation but was enhanced relative to that in the non-pregnant or early pregnant state. 4. Basal lipolysis also tended to be greatest at term. 5. Under conditions where the production of cyclic AMP was not rate limiting for the stimulation of lipolysis, that is in the presence of dibutyryl cyclic AMP (1 mM) or adrenaline (15 muM) plus phentolamine (13 muM) plus caffeine (1 mM), the release of glycerol in cells from women at term and in the puerperium was greater than that in women in the non-pregnant or early pregnant state. 6. Cell levels of cyclic AMP rose after incubation with adrenaline (6 muM) plus phentolamine or adrenaline (15 muM) plus phentolamine plus caffeine (1 mM) but were similar in all four groups of women. 7. It is concluded that the observed enhancement of lipolysis demonstrated in fat cells from women at the end of pregnancy reflects an increase in hormone-sensitive lipase activity rather than a modification of hormone receptor site sensitivity or of the rates of synthesis or breakdown of cyclic AMP. 8. This increase in adipose tissue lipolysis at the end of gestation could contribute to the reported rise in plasma nonesterified fatty acids in the final weeks of pregnancy.
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PMID:The effect of pregnancy on the control of lipolysis in fat cells isolated from human adipose tissue. 16 84


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