Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LIPASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,315 records · Page 73Linked to original sources
PubMed1979

Triglyceride lipase activity and human platelets.

The activity of triglyceride lipases in human postheparin plasma is significantly higher in platelet rich than platelet poor plasma. This holds for total activity, lipoprotein lipase (LPL) activity, and hepatic triglyceride lipase (H-TGL) activity. Gel filtration of platelet rich postheparin plasma on Sepharose 2 B will separate platelets from triglyceride lipase activity. The very small triglyceride lipase activity of isolated platelets is inhibited by 1.0 M NaCl, slightly inhibited by specific antibody to hepatic lipase, and not influenced by specific antibody to lipoprotein lipase.

Blood Platelets↗
PubMed1983

Insulin-mediated modifications of myocardial lipoprotein lipase and lipoprotein metabolism.

Recirculating organ perfusion in vitro was conducted with hearts from control rats, animals given a single dose of streptozotocin (65 mg/kg) 48 h earlier, and streptozotocin-treated rats administered insulin (5 units), 2 h prior to organ perfusion. During 45-min perfusions, the lipolysis of very low density lipoprotein (VLDL) triglyceride was significantly less in hearts from diabetics than in controls (41.9 +/- 7.3% of control). This was associated with significant reductions in heparin-releasable (functional) lipoprotein lipase and tissue lipoprotein lipase of perfused hearts. The decreases in VLDL triglyceride metabolism and the levels of myocardial lipoprotein lipase were completely reversed by treatment of diabetic rats with insulin 2 h prior to study. Similar improvement of VLDL triglyceride metabolism and increases in myocardial lipoprotein lipase activity were observed in hearts from diabetic rats by direct addition of 100 milliunits/ml of insulin to the recirculating perfusion media. Under these conditions, the increase in both fractions of lipoprotein lipase in response to insulin was completely inhibited, and utilization of VLDL triglyceride was partially inhibited by pre-perfusion with cycloheximide for 10 min. The data derived from either VLDL triglyceride lipolysis in organ perfusion or direct measurement of myocardial lipoprotein lipase demonstrate a direct effect of insulin on myocardial lipoprotein lipase activity, and suggest that the response to insulin may be due in part to effects on protein synthesis.

Animals↗
PubMed1984

Colipase and lipase secretion in childhood-onset pancreatic insufficiency. Delineation of patients with steatorrhea secondary to relative colipase deficiency.

Pancreatic lipase and colipase secretion was assessed in 64 patients with pancreatic disease, 24 of whom had steatorrhea, and in 14 control subjects. A wide range of lipase and colipase secretion was seen in patients both with and without steatorrhea. Considerable loss of pancreatic lipase and colipase secretion had to occur before steatorrhea developed, as the highest hourly secretion of lipase and colipase in this group of patients was less than 4% and less than 2%, respectively, of the lowest values recorded in normal subjects. Colipase and lipase outputs were very strongly correlated (r = 0.96) throughout the range of pancreatic function. Lipase was always unsaturated with respect to colipase, but in only a limited number of patients with relatively low pancreatic secretion was the degree of unsaturation greater than 2 standard deviations below the mean. The importance of low saturation or low colipase secretion was evident in a group of 11 patients with a narrow range of lipase secretion in a transitional zone between secretion rates associated with steatorrhea and with normal fat excretion. In this group, 7 patients were identified in whom colipase deficiency appeared to be the sole cause of steatorrhea. The correlation of colipase secretion with the level of fecal fat excretion was highly significant (p less than 0.001) and indicated that fat digestion and subsequent fat absorption depended on colipase secretion up to at least a level of 25% fecal fat excretion. Nonpancreatic factors could well govern the extent of fat absorption above this level, as colipase secretory values in this range were uniformly low.

Adolescent↗
PubMed1982

Lipoprotein lipase activity in human and guinea-pig placenta.

Human and guinea-pig placental activity was measured in tissue extracts and in medium in which tissue fragments have been incubated. Lipase activity was estimated from measured rates of release of 3H-labelled fatty acids from a 3H-labelled triacylglycerol substrate. Whole tissue lipase activity was 1.6 +/- 0.3 units/g (mean +/- SEM, mumol of unesterified fatty acid release/min) in the human, and 87.1 +/- 7.3 units/g in guinea-pig placental tissue. 70% of the human and 56% of the guinea-pig placental activity was lost on treating the tissues with cold acetone. Sodium chloride (0.75 M) decreased activity by 50% in extracts from both species. Lipase activity was released into media when placental fragments were incubated. The addition of heparin increased the release of lipase from human placenta but not significantly from that of the guniea-pig. Insulin had no effect on placental lipase activity from either species. It is concluded that the placentas of both species contain at least two lipases. One of these, which constituted a large of the total, had the characteristics of lipoprotein lipase.

Animals↗
PubMed1981

Lipoprotein lipase activity in adipose tissue of spontaneously hyperlipidemic rats.

The lipoprotein lipase activity in adipose tissue of Sprague-Dawley rats 1, 4, 9 and 15 months of age, was investigated. The study revealed that a significant inverse relationship exists between serum triglyceride level and lipoprotein lipase activity in epididymal fat pad. Thus, the lipoprotein lipase activity in 1 and 15 months old rats are on the average 5.3 and 1.1 nkat/g wet weight, respectively, simultaneously as serum triglyceride level increase from 0.74 mmol/l to 3.51 mmol/l, respectively. It is suggested that impaired removal of very low density lipoproteins is one possible explanation of the enhanced levels of this lipoproteins in the old rat. The lipase activity investigated had the characteristic properties of lipoprotein lipase, i.e. it was activated by the addition of serum, inhibited by high ionic strength and varied with the nutritional state. However, it could not be exclude that monoacylglycerol lipase present in epididymal fat pad also decreased with age. The possible connection between the age-related reduction of lipoprotein lipase activity in epididymal fat pad and the age-related gomerulonephritis found in these rats is discussed.

Adipose Tissue↗
PubMedDate not supplied

[Isolation and characteristics of Penicillium roqueforti lipases].

Lipase were isolated from Penicillium roqueforti 141, purified and their properties were studied. Proteins were precipitated with (NH4)2SO4 from the cultural broth of this organism, and then subjected to gel filtration through Sephadex G-100 and chromatography on DEAE-cellulose; the procedure yielded a purified preparation consisting of three lipolytically active proteins. Disc electrophoresis in polyacrylamide gel confirmed the homogeneity of the lipases. The molecular weights of the enzymes were 7930, 9100 and 11 420 respectively, according to the data of gel filtration through Sephadex G-150. The lipases differed in their substrate specificity. Lipase III was most active in hydrolysis of plant oils containing mainly unsaturated fatty acids. Lipase II most effectively hydrolyzed synthetic triglycerides containing saturated fatty acids, in particular, tricaproin, tricaprilin and trimyristin. Tributyrin was more actively hydrolyzed with lipase I as compared to lipases II and III.

Enzyme Activation↗
PubMed1979

Lipase and colipase in canine pancreatic juice as etiologic factors in fat necrosis.

Lipase and colipase have been purified to homogeneity from canine pancreatic juice. The purity of the lipase and colipase preparations was established by acrylamide gel electrophoresis. Either lipase or colipase alone did not produce fat necrosis when injected intraperitoneally into mice. Fat necrosis was seen only when both lipase and colipase were used together. Selective removal of lipase from fresh canine pancreatic juice by immunoprecipitation with an antilipase specific antiserum also eliminated its fat necrotizing activity. Together, these results identify the fat necrotizing factors to be pancreatic lipase and colipase. Their uncontrolled release during acute pancreatitis is believed to constitute the cause of fat necrosis. The absolute amount of lipolytic activity was not found to be the crucial factor in the induction of fat necrosis. It is suggested that the colipase molecule may have other functions besides enhancing the lipolytic activity of purified lipase in causing fat cell necrosis.

Animals↗
PubMed1976

Affinity chromatography of lipase with hydrophobic ligands coupled to cyanogen bromide-activated agarose.

The behavior of lipase produced by Pseudomans mephitica var. lipopytica toward hydrophobic residues coupled to spacer gels that were prepared by coupling a primary amine to CNBr-activated agarose, was studied. The lipase adsorbed on the ligand of a long unbranched aliphatic chain, a benzene ring, or deoxycholic acid was only slightly or not all eluted at pH 5 or pH 11 by buffers containing 1 M NcC1. The lipase was eluted by liquid containing a surfactant or an organic solvent miscible with water, indicating greater involvement of hydrophobic forces. The adsorption of propane, cyclopentane, cyclohexane, cycloheptane, or chrysene appears to be achieved through electrostatic forces, inasmuch as desorption was caused by buffer containing 1 M NaC1 at pH 11. The amount of lipase adsorbed on these hydrophobic ligands was about the same as that adsorbed on the ligands belonging to the first group. Since little lipase wad adsorbed on cyclopropane, cycloctane, pyridine, methane, n-pentane, or branched aliphatic chains, these ligands appear to impose steric hindrance on the adsorption of lipase, or they may be too small to fit into the hydrophobic sites of lipase.

Amines↗
PubMed1993

Identification and cloning of GP-3 from rat pancreatic acinar zymogen granules as a glycosylated membrane-associated lipase.

The protein components of highly purified secretory granule membranes and the granule contents from rat exocrine pancreas were characterized by two-dimensional polyacrylamide gel electrophoresis, protein staining, lectin absorption, and Western blotting with anti-secretory protein antibodies. NH2-terminal amino acid sequence was obtained for a approximately 53-kDa glycoprotein denoted GP-3, present only in granule membrane preparations where it was resistant to washing with Na2CO3 and KBr. The sequence of this protein showed homology to pancreatic lipase but was distinct from the NH2-terminal sequence of a 50-kDa content protein presumed to be secretory lipase. Polymerase chain reaction amplification with degenerate oligonucleotide primers to GP-3 and secretory lipase gave partial length subclones that were used to isolate clones from a rat pancreas cDNA library. Dideoxy sequencing of full-length subclones of GP-3 revealed the predicted amino acid sequence for a mature protein of 452 amino acids with a potential N-linked glycosylation site and a deglycosylated molecular weight of 50,860. The GP-3 sequence possesses the serine esterase consensus sequence G-X-S-X-G centered around Ser154 and the catalytic state triad Asp178-His265-Ser154 characteristic of pancreatic lipases. Northern blot analysis of various rat tissues showed GP-3 expression solely in pancreas. Comparison of GP-3 nucleotide and amino acid sequence, along with pancreatic lipases of various species including rat, shows extensive homologies to both proteins and reveals an underlying diversity in the pancreatic lipase family. Close homology is observed between GP-3 and a lipase molecule previously isolated from mouse cytotoxic T cells.

Amino Acid Sequence↗
PubMed1996

Evaluation of an automated colorimetric assay for the measurement of lipase activity in canine sera.

An automated colorimetric method for determining lipase activity in canine sera was evaluated for precision, linearity and correlation to existing assay methods. The colorimetric method was a commercial reagent that used a series of enzymatic reactions based on the hydrolysis of 1,2 diglyceride by pancreatic lipase. Within-run and between-run coefficients of variation were < 6.8% and < 8.3%, respectively. Linearity was determined to be at least 1366 U/L. Canine serum lipase concentrations attained using the colorimetric method were compared to both titrimetric and dry-film methods for measuring serum lipase activity, resulting in significant (P < or = 0.05) correlation coefficients of 0.92 and 0.77, respectively. Canine serum lipase concentrations measured using the colorimetric assay on 2 different automated analyzers had a significant (P < or = 0.05) correlation coefficient of 0.92. A laboratory reference range using serum samples from 56 healthy dogs (0-561 U/L) was established. There were no significant (P < or = 0.05) differences in mean serum lipase concentrations comparing male and female dogs or comparing young dogs (< or = 3 y) to mature (4-7 y) and older (> 7 y) dogs using this assay. It was concluded that the automated colorimetric assay was a reliable indicator of canine serum lipase activity and offered several advantages, including small sample volume and short analysis time.

Animals↗
PubMed1996

Relative roles of the LDL receptor, the LDL receptor-like protein, and hepatic lipase in chylomicron remnant removal by the liver.

Studies were carried out in mice utilizing inhibitors of several cell surface molecules to evaluate their relative roles in chylomicron remnant removal. Anti-LDL receptor antibody inhibited approximately 45% of rapid remnant removal from plasma, prolonged their half life (63 s to 115 s) and reduced hepatic uptake by 45%. Receptor-associated protein (RAP) (1 mg/mouse), a high affinity inhibitor of the LDL receptor-related protein (LRP) and a low affinity inhibitor of the LDL receptor decreased remnant removal approximately 55%, prolonged the half life from 63 s to 230 s, and reduced hepatic uptake by 70%. RAP, but not anti-LDL receptor antibody, inhibited splenic uptake. With both injected together, an incremental effect was seen; plasma removal decreased 60%, T1/2 increased to 290 s, and hepatic uptake decreased by 80%. Thus, it is likely that virtually all of the very rapid removal of remnants from the plasma by the liver requires the presence of at least one of these members of the LDL receptor family. Anti-hepatic lipase antibody caused a small but significant delay in remnant removal from plasma and a larger decrease in hepatic uptake (22.5%). It doubled adrenal uptake. The anti-hepatic lipase antibody was not additive with either the anti-LDL receptor antibody or RAP. Anti-rat hepatic lipase antibody did not inhibit lipolysis by mouse hepatic lipase, suggesting that lipolysis is not the way hepatic lipase enhances remnant uptake. Hepatic lipase bound to remnants to a greater degree than it bound to other lipoproteins. Together these data suggest that hepatic lipase may serve as a binding site for chylomicron remnants, thereby enhancing their affinity for the liver surface, and thus removal by the proteins of the LDL receptor family. Other molecules may also play a role in removal from the circulation under conditions where the LDL receptor family receptors are absent or occupied.

Animals↗
PubMed1996

Dimeric lipoprotein lipase is bound to triglyceride-rich plasma lipoproteins.

Lipoprotein lipase hydrolyzes the triglyceride-rich core of chylomicrons and very low density lipoproteins. It is also a ligand, in vitro, for binding of lipoproteins to the low density lipoprotein receptor-related protein and may play a central role in the receptor-mediated removal of triglyceride-rich lipoproteins. The aim of the present study was to determine to which lipoprotein subclass the enzyme is bound in preheparin plasma and when released into plasma by heparin injection. Tetrahydrolipstatin, a potent inhibitor of serine lipases, was used to block lipolytic activity, thereby preventing changes in plasma lipoproteins due to ex vivo lipolysis. To analyze the distribution pattern of lipoprotein lipase dimers among lipoprotein classes, a specific ELISA was used and gel filtration was performed in pre- and postheparin plasma from five subjects with triglyceride ranging from 69 to 522 mg/dl. When lipolytic activity was not inhibited, lipoprotein lipase dimers eluted in association with low and high density lipoproteins, reproducing results previously obtained by several groups of investigators. However, in pre- and postheparin samples treated with tetrahydrolipstatin, most of the dimeric enzyme was found associated with very low density lipoprotein particles. In conclusion in pre- and postheparin samples most of the lipoprotein lipase dimers are associated with very low density lipoproteins when ex vivo lipolytic activity is inhibited, which supports the hypothesis that, in vivo, lipoprotein lipase may affect the receptor-mediated removal of these particles. Moreover, it suggests that the association between lipoprotein lipase and cholesterol-rich lipoproteins might be an ex vivo phenomenon due to lack of inhibition of lipolytic activity.

Adult↗
PubMed1996

Longitudinal study on lipoprotein profile, high density lipoprotein subclass, and postheparin lipases during gestation in women.

To understand the mechanism responsible for maternal hyperlipidemia, 25 healthy pregnant women were studied longitudinally during the three trimesters of gestation and at post-partum, and 11 were studied again at post-lactation. Triglyceride and cholesterol levels increased with gestation in all the lipoprotein fractions. However, the greatest change appeared in low density (LDL) and high density (HDL) lipoproteins, both of which showed an increase in their triglyceride/cholesterol ratio. The proportional distribution of HDL subfractions showed that the HDL2b fraction was the only one that increased with gestation, whereas both HDL3a and HDL3b had the greatest decrease. Cholesteryl ester transfer protein activity increased during the second trimester of gestation. While postheparin lipoprotein lipase activity decreased during the third trimester, postheparin hepatic lipase activity progressively decreased from the first trimester. The 17 beta-estradiol, progesterone, and prolactin hormones progressively increased from the first trimester of gestation. The lipoprotein-triglyceride values correlated linearly and negatively with the logarithm of either postheparin lipase activities, HDL-triglycerides showing the highest correlation coefficient when plotted against the hepatic lipase values (r = -0.757). It appeared that the highest correlation between any of the HDL subclasses and the activity of the enzymes was for hepatic lipase activity versus HDL2b (r = 0.456) or HDL3a (r = 0.519). A significant lineal correlation also appeared between the postheparin hepatic lipase activity and the logarithm of any of the sex hormones studied, the highest value corresponding to estradiol (r = -0.783). Therefore, during gestation, the effect of estrogen in enhancing very low density lipoprotein (VLDL) production and decreasing hepatic lipase activity plays a key role in the accumulation of triglycerides in lipoproteins of density higher than VLDL.

Adult↗
PubMed1997

Hepatic lipase is abundant on both hepatocyte and endothelial cell surfaces in the liver.

The cellular location of hepatic lipase was investigated in transgenic rabbits that expressed human hepatic lipase in the liver. The binding of monoclonal antibodies to human hepatic lipase, as detected by either fluorescence-tagged or gold-conjugated secondary antibodies, showed that hepatic lipase was concentrated at the surfaces of hepatic sinusoids. This distribution was the same as observed in the human liver. At the ultrastructural level, immunogold labeling of the space of Disse showed hepatic lipase on both lumenal and sublumenal surfaces of rabbit liver sinusoidal endothelial cells. An equivalent amount of hepatic lipase also was found on the external surfaces of hepatocyte microvilli in the space of Disse, as well as in the interhepatocyte spaces. The distribution suggests that a majority of the hepatic lipase produced by the liver is associated with hepatocyte surfaces, consistent with the functions of this enzyme in lipoprotein metabolism.

Animals↗
PubMed1997

Purification and characterization of lipase from a raw-milk yeast (Trichosporon asteroides).

A lipase-producing yeast strain was isolated from raw milk. It was identified as Trichosporon asteroides strain LP005. The lipase from this yeast was purified 8-fold to homogeneity for further characterization. The purification process for this lipase included (NH4)2SO4 precipitation at 70% saturation and gel filtration on Sephadex G-200. The molecular mass of the lipase was 37 kDa as determined by SDS/PAGE. The optimum pH and temperature for activity were pH 5.0 and 60 degrees C. The lipase was stable over a wide pH range (3.0-10.0) and at temperatures lower than 70 degrees C. The chelating agent EDTA did not affect activity of the enzyme, and this suggested that it was not a metalloenzyme. Treatment of tuna oil with T. asteroides LP005 lipase gave approx. 35 and 47% increases in the concentration of eicosapentaenoic acid and docosahexaenoic acid respectively. Thus, this lipase could potentially be used for the concentration step in the production process of such polyunsaturated fatty acids.

Animals↗
PubMed1998

Identification of the epitope of a monoclonal antibody that inhibits heparin binding of lipoprotein lipase: new evidence for a carboxyl-terminal heparin-binding domain.

A panel of 13 monoclonal antibodies to avian lipoprotein lipase (LPL) was screened for inhibition of LPL binding to primary avian adipocytes. One monoclonal antibody, designated xCAL (monoclonal antibody to chicken adipose lipoprotein lipase) 3-6a, was found to inhibit the binding of LPL to primary avian adipocytes. In solid phase assays, xCAL 3-6a inhibited the binding of LPL to both heparan sulfate and heparin. XCAL 3-6a did not inhibit the catalytic activity of the avian enzyme. The monoclonal antibody was not found to cross-react significantly with bovine lipoprotein lipase. In order to determine the location of the epitope of xCAL 3-6a on lipoprotein lipase, several avian lipoprotein lipase deletion mutants were constructed and produced as glutathione S-transferase (GST) fusion proteins in E. coli. These mutants were screened for their ability to react with xCAL 3-6a using Western blotting. The minimum continuous fragment of lipoprotein lipase that was required for reactivity contained the amino acids 310 to 450. Site-directed mutagenesis of basic residues 321, 405, 407, 409, 415, and 416 revealed that Arg 405 is necessary for the interaction of LPL with xCAL 3-6a. Additional deletions of either the amino- or carboxyl-terminal portion of the fragment containing residues 310-450 resulted in loss of antibody binding, suggesting that the epitope is a discontinuous one that is formed when the termini are brought together through protein folding. Heparin-Sepharose chromatography of wild-type LPL and a mutant LPL in which the well-characterized heparin-binding sequence (Arg 281-Lys 282-Arg 284) has been mutated was carried out in the presence and absence of xCAL 3-6a. These experiments indicate that lipoprotein lipase contains a heparin-binding domain, in addition to Arg 281-Arg 284, that can be blocked by xCAL 3-6a.

Adipocytes↗
PubMed1998

Accelerated lipoprotein uptake by transplantable hepatomas that express hepatic lipase.

To test the hypothesis that hepatic lipase plays a key role in lipoprotein removal in vivo, a novel system was used. Hepatoma cells (HTC 7288c) were transfected with a cDNA encoding hepatic lipase in culture and grown as solid tumors in vivo. In culture, transfected cells degraded chylomicron remnants and low density lipoprotein (LDL) somewhat more efficiently than untransfected cells. Tumors from the transplanted cells produced hepatic lipase localized to the surface of tumors from transfected cells but not tumors from non-transfected cells, grown in the same rat. The tumors from transfected cells removed, per gm of tissue, 34% (P < 0.001) more 125I-labeled LDL than tumors from non-transfected cells in the same animal. The uptake of chylomicron remnants (by tumors from transfected cells) was also modestly enhanced (15 +/- 6%, P < 0.005). There were no differences in the uptake of 125I-labeled albumin or 125I-labeled asialoglycoprotein. Compared to the liver, the untransfected tumors took up 12%, and the transfected tumors took up about 18% as much LDL per gram of tissue. The uptake of chylomicron remnants compared to liver was far lower. Both types of tumors had about twice as much LDL receptor related protein as the liver. Wild-type tumors had the highest level of LDL receptor, twice hepatic lipase-secreting tumors, and six times that of the liver. Using the novel approach of transfecting transplantable tumor cells with hepatic lipase, the ability of hepatic lipase to facilitate the removal of apoB-containing lipoproteins was demonstrated. The liver still removes low density lipoprotein and especially chylomicron remnants more rapidly than the tumors, suggesting factors in addition to hepatic lipase and LDL receptor level play a major role in hepatic lipoprotein removal.

Animals↗
PubMed1998

Purification and characterization of a regiospecific lipase from Aspergillus terreus.

Aspergillus terreus lipase was purified to homogeneity with 18.0% yield. The specific activity of the enzyme increased from 20.80 to 250 U/mg of protein. Ion exchange on Q-Sepharose was highly effective in the purification process. The molecular mass of the purified enzyme was 41+/-1 kDa as determined by SDS/PAGE. The purified lipase showed excellent temperature tolerance (15-90 degreesC) and was highly thermostable, retaining 100% activity at 60 degreesC for 24 h. It showed good pH tolerance (3.0-12.0) and was stable over a pH range of 4.0-10.0 for 24 h. The activity of the enzyme was inhibited by ionic detergents, whereas non-ionic detergents stimulated enzyme activity. Mg2+ and Ca2+ ions stimulated lipase activity, whereas Co2+, Cu2+, Ni2+ and Fe3+ ions caused inhibition. The enzyme was unaffected by the metal chelator EDTA or by 2-mercaptoethanol and potassium ferrocyanide. At a concentration of 100 microM, 3,4-dichloroisocoumarin caused weak inhibition with 40% loss of activity, but diethyl p-nitrophenyl phosphate at the same concentration strongly inhibited enzyme activity (98.12% loss of activity), confirming that the A. terreus lipase is a serine hydrolase. The lipase was highly active on pig fat (151% relative activity) and groundnut oil (103% relative activity) and least active on kusum oil (18% relative activity). Extensive dialysis did not affect enzyme activity up to 168 h, suggesting the absence of any dialysable cofactor in the enzyme. The A. terreus lipase retained significant activity on freeze-drying and had a shelf-life of more than 6 months at room temperature. The A. terreus lipase exhibited 1,3-regiospecificity and was stable in various organic solvents.

Aspergillus↗