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PubMed1993

An accessory gene, lipB, required for the production of active Pseudomonas glumae lipase.

Pseudomonas glumae PG1 is able to secrete lipase into the extracellular medium. The lipase is produced as a precursor protein, with an N-terminal signal sequence. A second open reading frame (ORF) was found immediately downstream of the lipase structural gene, lipA, a situation found for the lipases of some other Pseudomonas species. Inactivation of this ORF resulted in a lipase-negative phenotype, indicating its importance in the production of active extracellular lipase. The ORF, lipB, potentially encodes a protein of 353-amino-acid residues, having a hydrophobic N-terminal (amino acids 1 to 90) and a hydrophilic C-terminal part. As a first step in determining the role of LipB, its subcellular location was determined. The protein was found to fractionate with the inner membranes. The expression of fusions of lipB fragments with phoA revealed an N(in)-C(out) topology for the LipB protein, which was confirmed by protease accessibility studies on EDTA-permeabilized cells and on inverted inner membrane vesicles. These and other results indicate that most of the LipB polypeptide is located in the periplasm and anchored to the inner membrane by an N-terminal transmembrane helix, located between amino acids 19 and 40.

Amino Acid Sequence↗

PubMed1981

The bile-salt-stimulated lipase in human milk. Purification and characterization.

The bile-salt-stimulated lipase was purified from human whey by chromatography on heparin-Sepharose and Affi-Gel blue. The purified enzyme gave a single band with a molecular weight of 90 000 on dodecylsulphate/polyacrylamide gels and this band accounted for at least 98% of the protein on the gel. An antiserum to the purified lipase completely inhibited the enzyme activity and gave a single precipitate against human whey and purified lipase. The bile-salt-stimulated lipase was inhibited by diisopropylfluorophosphate, which bound to the purified enzyme in a molar ratio of 0.85 mol/mol. The lipase is a glycoprotein with a high content of acidic amino acid residues and an isoelectric point of around 4. Proline constitutes more than 10% of the total amino acid residues. The purified lipase has a turnover number of around 150 S-1.

Amino Acids↗

PubMed1987

Human gastric lipase. A kinetic study with dicaprin monolayers.

The effects of several proteins on the hydrolysis at pH 3.0 of didecanoylglycerol monolayers by human gastric lipase were investigated. Among the six proteins tested (bovine serum albumin, myoglobin, a protein inhibiting lipase isolated from soya bean, melittin, beta-lactoglobulin and ovalbumin), only the first three proteins were found to inhibit lipase activity. The inhibition capacity of the proteins was not related to the decrease in interfacial tension or to their isoelectric points. However, inhibition of human gastric lipase by proteins may be correlated with the penetration power of the protein into the lipid interface. It is hypothesized that this lipase has a higher penetration power than that of pancreatic lipase, even though the former enzyme is more susceptible to interfacial denaturation.

Diglycerides↗

PubMed1989

Role of a sulfhydryl group in gastric lipases. A binding study using the monomolecular-film technique.

Native human and rabbit gastric lipases (HGL and RGL, respectively) were inactivated after modification of one sulfhydryl group/enzyme molecule. HGL and RGL were covalently labeled using 5,5'-dithiobis(2-nitro-[14C]benzoic acid) and the interaction of 2-nitro-5-thio-[14C]benzoic-acid-labeled lipases ([14C]Nbs-lipases) with monomolecular lipid films was investigated. Our results show that [14C]Nbs-lipases bind to lipid films as efficiently as native HGL or RGL. The critical surface pressure pi c and the maximal surface pressure (delta pi max) of [14C]Nbs-lipases were enhanced in comparison with those of native RGL and HGL. These changes in behavior were probably due to an increase in hydrophobicity brought about, directly or indirectly, by the binding of the Nbs radical. This chemical modification thus blocks the hydrolysis site and reinforces the hydrophobic character of the gastric lipases.

Animals↗

PubMed2006

Comparison of lipase activity in peritoneal fluid of dogs with different pathologies--a complementary diagnostic tool in acute pancreatitis?

A clinical diagnosis of acute pancreatitis is often difficult to obtain. Histopathology remains the gold standard, whereas clinical signs, diagnostic imaging and laboratory testing, even in combination, may be insufficient. In a prospective study, lipase activity in ascitic fluid of various aetiologies was determined in 44 dogs in order to investigate its performance in cases of acute pancreatitis. Data of simultaneously determined blood lipase activities were available in 27 dogs. Lipase activity was measured by a colorimetric assay. A complete peritoneal fluid analysis was performed. Dogs were divided into four groups, according to their final diagnosis: acute pancreatitis (A), abdominal trauma (B), abdominal neoplasia (C) and others (hepatic or cardiac diseases) (D). Dogs with acute pancreatitis had a significantly higher peritoneal lipase activity than those in other groups (P < or = 0.024), while no significant difference was found between the other groups (P > or = 0.734). Blood lipase activity as well as protein content and total cell count of the ascitic fluid did not show any significant difference between groups. Data show that determination of lipase activity in dogs that develop ascites may be useful in complementing the diagnosis of acute pancreatitis.

Abdominal Injuries↗

PubMed2001

Serum amylase and lipase activities in normal pregnancy: a prospective case-control study.

OBJECTIVE: The diagnosis of acute pancreatitis during pregnancy is usually based on the association of upper abdominal pain, nausea or vomiting, and elevated serum amylase or lipase activities. The changes in these enzymatic activities have not been clearly established during normal pregnancy. The aim of this study was therefore to evaluate serum amylase and lipase activities in healthy pregnant women. METHODS: Serum amylase and lipase activities were measured in 103 pregnant women (first trimester, n = 34; second trimester, n = 36; third trimester, n = 33) and in 103 nonpregnant women matched for age and not receiving oral contraception. RESULTS: Serum amylase activity was similar in pregnant women and nonpregnant women during all trimesters of pregnancy. Serum lipase activity was significantly lower during the first trimester of pregnancy compared to nonpregnant women (48.6+/-27.6 vs 59.2+/-29.3 IU/L, p < 0.05) and compared to the third trimester (48.6+/-27.6 vs 76.3+/-35.8 IU/L, p < 0.001). Serum lipase activity was not statistically different between pregnant and nonpregnant women during the second and third trimesters. CONCLUSION: An increase in serum amylase and lipase activities during pregnancy should be taken into account, as in nonpregnant women.

Adult↗

PubMed1999

Occurrence of a lipase in spores of Alternaria brassicicola with a crucial role in the infection of cauliflower leaves.

Alternaria brassicicola is a pathogen that penetrates directly through the host cuticle thanks to several serine esterases, according to our findings. Among these, an 80-kDa lipase (E.C 3.1.1. 3) was detected by SDS-PAGE and immunoblotting in the water washings of ungerminated spores. The purified lipase cross-reacted with Botrytis cinerea anti-lipase antibodies, which were reported to inhibit the in vitro lipase activity. Anti-lipase antibodies were added to a conidial suspension of A. brassicicola prior to inoculation. As a result, blackspot lesions were reduced by 90% on intact cauliflower leaves, but not on leaves from which surface wax had been removed. Spore surface-bound lipase is thought to interact closely with epicuticular leaf waxes for adhesion and/or penetration of the fungal propagules during the early stages of host-parasite interactions.

Alternaria↗

PubMed1977

Role of feeding on lipase activity in gastric contents.

Lipase activity was recorded in gastric contents collected from healthy term and preterm neonates. In contrast to pancreatic lipase activity this lipase activity was higher at pH 5.5 than at pH 8.0 and it was more resistent to acid inactivation. Lipase activity was found in gastric contents from all infants who were regularly fed, but was not present in gastric contents from some infants when collected before regular feeding was established. During test meals lipase activity in gastric contents increased considerably in all infants studied. During such a test meal there was a progressive relative decrease in triglycerides whilst diglycerides showed a relative increase suggesting an active lipolytic process in the stomach. An assay procedure for determination of lipase activity in gastric contents is also described.

Diglycerides↗

PubMed1982

Lingual lipase. Its role in lipid digestion in infants with low birthweight and/or pancreatic insufficiency.

At birth both pancreatic lipase and carboxylic ester hydrolase, two important lipolytic enzymes secreted by the pancreas, are present in duodenal contents but the activities of these enzymes are low. Another enzyme of possible importance in lipolysis is the lingual lipase which is secreted from serous glands present at the posterior part of the tongue. The enzyme is present already at birth and has been found in gastric contents from preterm infants in the 34th gestational week. The secretion of lingual lipase is stimulated by feeding and it is resistent against acid inactivation. The activity in gastric contents increases after feeding. This lipase hydrolyzes dietary triglycerides to mainly diglycerides and free fatty acids and may serve as a complement to the poorly developed pancreatic lipase activity. Furthermore, by the formation of polar lipolytic products the digestibility of dietary lipids in the duodenum may increase. Human milk lipase contributes to the lipolysis. It is inactive in the milk but becomes activated by the bile acids in the duodenum. Balance studies in preterm infants have shown that by pasteurization of human milk fat absorption decreases by one third.

Bile Acids and Salts↗

PubMed2005

Validation and diagnostic efficacy of a lipase assay using the substrate 1,2-o-dilauryl-rac-glycero glutaric acid-(6' methyl resorufin)-ester for the diagnosis of acute pancreatitis in dogs.

BACKGROUND: Increased serum lipase activity has been used historically to support the diagnosis of acute pancreatitis, a common disease in dogs. Most of the lipase assays that are currently in use lack optimum sensitivity and specificity. OBJECTIVE: The objectives of this study were to 1) validate the 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester (DGGR) assay for determination of lipase activity in canine serum and 2) compare results, reference intervals, sensitivity, and specificity of the DGGR assay with a standard 1,2-diglyceride (1,2 DiG) assay for diagnosing acute pancreatitis in dogs. METHODS: Precision, linearity, and interference studies were performed for method validation on a Hitachi 911 analyzer. Lipase results from the DGGR and 1,2 DiG assays were compared by linear regression analysis. Sensitivity, specificity, and diagnostic efficacy were determined for both assays on a population of 30 dogs, 15 of which had acute pancreatitis based on history, clinical signs, and ultrasound findings. RESULTS: Within-run and within-day coefficients of variation (CVs) were low (<3%), with higher day-to-day CVs (< or =14 %). The assay was linear between 8 and 2792 U/L. No significant interference by hemolysis and lipemia was found. Poor correlation was found between the assays (r(s)=0.84). The lipase reference interval was 8-120 U/L for the DGGR assay and 30-699 U/L for the 1,2 DiG assay. Sensitivity and specificity for the diagnosis of pancreatitis were 93% and 53%, respectively, for the DGGR assay and 60% and 73% for the 1,2 DiG assay. Receiver operating characteristic curve analysis showed similar areas under the curve. CONCLUSIONS: On the basis of this study, the DGGR method is considered adequate for assaying serum lipase activity in dogs. The high sensitivity of the DGGR assay suggests it may be a useful screening test for canine pancreatitis.

Animals↗

PubMed1992

Quantitative spectrophotometric assay for staphylococcal lipase.

We report the development of a specific spectrophotometric assay for the quantitative determination of lipase activity in Staphylococcus aureus. The assay is based on the rate of clearance of a tributyrin emulsion, and it can detect as little as 1.0 micrograms of purified Pseudomonas lipase per ml. By comparison with the reaction rates obtained with Pseudomonas lipase, we calculated that S. aureus PS54C and S6C produce approximately 15 and 60 micrograms of extracellular lipase per ml, respectively. Neither PS54, which is lysogenized with the converting bacteriophage L54a and is consequently lipase negative (Lip-), nor KS1905, a Lip- transpositional mutant of strain S6C, was positive in our spectrophotometric assay. The specificity of the spectrophotometric tributyrin assay was confirmed with a triolein plate assay; supernatants from S6C and PS54C hydrolyzed triolein, while supernatants from PS54 and KSI905 did not. In contrast to the results of the spectrophotometric tributyrin assay, all enzyme preparations tested (including commercially purified esterase) were positive when examined by a tributyrin plate assay. The lack of specificity in the tributyrin plate assay emphasizes the need to interpret the results of tributyrin lipolysis kinetically for assessing lipase activity in S. aureus.

Bacterial Proteins↗

PubMed1983

Low pancreatic lipase in insulin-dependent diabetics.

Serum samples obtained from 20 insulin-dependent diabetics (IDD), 23 non-insulin-dependent diabetics (NIDD) and 30 controls were assayed for their pancreatic lipase activity, immunoreactive trypsin concentration and glycosylated haemoglobin (HbA1) respectively. The distribution of serum pancreatic lipase activity in normal subjects and diabetics was nonparametric. The median serum lipase activity in IDDs (86 U/l) was significantly lower that that in controls (131 U/l, p less than 0.002) and NIDDs (126 U/l, p less than 0.001). There was a significant correlation between serum pancreatic lipase activity and serum IRT concentration (r = 0.65, p less than 0.001). Neither pancreatic lipase activity nor IRT was related to HbA1 concentrations. These data show for the first time that serum pancreatic lipase activity is diminished in IDDs.

Diabetes Mellitus↗

PubMed2002

Acute regulation of hepatic lipase secretion by rat hepatocytes.

Hepatic lipase is involved in cholesterol uptake by the liver. Although it is known that catecholamines are responsible for the daily variation of enzyme activity, the mechanisms involved are poorly understood. Rat hepatocytes incubated with adrenaline or other Ca(2+)-mobilizing hormones were used as an experimental model. Adrenaline reduced in a similar proportion the secretion of both hepatic lipase and albumin. The effect of adrenaline disappeared completely in cells exposed to cycloheximide. Adrenaline decreased incorporation of [35S]Met into cellular and secreted proteins, but it affected neither degradation of [35S]Met-prelabeled proteins nor the abundance of total and specific (albumin, hepatic lipase, beta-actin) mRNA. Other Ca(2+)-mobilizing agents had the opposite effect on hepatic lipase secretion: it was decreased by vasopressin but was increased by epidermal growth factor. Vasopressin and epidermal growth factor had the opposite effect on [35S]Met incorporation into cellular and secreted proteins, but neither affected hepatic lipase mRNA. The acute effect of adrenaline, vasopressin, and epidermal growth factor on hepatic lipase secretion is the consequence of the effect of these hormones on protein synthesis and is therefore nonspecific.

Adrenergic Agonists↗

PubMed1986

Secretion of triglyceride lipase from rat hepatocytes in culture: modulation by insulin and phenobarbital.

Hepatic triglyceride lipase (HTGL) was measured in primary rat hepatocytes maintained for 3 days under three different culture conditions: basal medium, basal medium plus insulin, and basal medium plus insulin and phenobarbital. The activity of HTGL secreted by these cells was measured by treating intact cells with heparin; intracellular enzyme was subsequently measured in cell homogenates. Insulin stimulated intracellular triglyceride lipase activity by 48% and extracellular lipase by 30%. Phenobarbital, an enzyme-inducing drug, caused a further 15% increase in extracellular hepatic triglyceride lipase; whereas, the intracellular activity was reduced. The presence of insulin greatly stimulated the rate of enzyme secretion, and this rate was not notably affected by the presence of phenobarbital. After 3 days in culture, the short term (2-8 h) synthesis and secretion of enzyme from cultures treated with insulin or insulin plus phenobarbital were equally inhibited by cycloheximide. Monensin also inhibited enzyme secretion in both cultures and caused a similar increase in intracellular lipase activities. Insulin did not significantly affect the proportion of intracellular enzyme (17.7% basal vs. 15.8% insulin). On the other hand phenobarbital produced a 20-30% reduction in the proportion of intracellular enzyme (12.5 vs. 17.7% basal or 15.8% insulin). These findings suggest a drug-induced redistribution of triglyceride lipase.

Animals↗

PubMed1984

Lipogenesis and lipoprotein lipase in human adipose tissue: reproducibility of measurements and relationships with fat cell size.

Lipogenesis from glucose and lipoprotein lipase activity were investigated in humans. The reliability of measurements was quantified and correlations with fat cell weight were assessed. Twenty-four subjects (7 women, 17 men) were studied twice within a 2-week period, along with 17 additional male subjects who were studied once and used only in the correlation analyses. All subjects were not regularly involved in an exercise-training program and were between 18 and 30 years of age. Following an overnight fast, adipose tissue specimens were obtained by suprailiac biopsy and fat cells were collagenase isolated. Mean fat cell weight was obtained from 400 to 500 cell diameter determinations per subject. Basal and insulin-stimulated fat cell lipogenesis from glucose were determined using D-[U-14C]glucose and were reported in nanomoles of glucose per hour per 10(6) cells. Adipose tissue heparin-releasable lipoprotein lipase activity was also determined and expressed in micromoles of free fatty acids per hour per gram of tissue and per 10(6) cells. Fat cell weight, basal and insulin-stimulated lipogenesis and lipoprotein lipase activity per gram showed high reliability of measurement, interclass and intraclass coefficients being 0.83 and over. Lipoprotein lipase activity per 10(6) cells showed a somewhat lower degree of reliability, interclass and intraclass coefficients being, respectively, 0.69 and 0.81. On the other hand, fat cell weight was positively correlated with lipoprotein lipase activity (r = 0.80), while no significant correlation was observed between basal lipogenesis and fat cell weight. Moreover, basal lipogenesis presented no significant correlation with lipoprotein lipase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1994

Regulation of myocardial lipoprotein lipase activity by diabetes and thyroid hormones.

Administration of streptozotocin (100 mg/kg) to adult Sprague-Dawley rats reduced both functional (heparin releasable) lipoprotein lipase activity in perfused hearts and total and heparin-releasable lipoprotein lipase activity in isolated cardiomyocytes, and produced a hypothyroid state (decreased plasma levels of triiodothyronine and thyroxine). Administration of replacement doses of triiodothyronine (3 or 10 micrograms/kg for 3 days) to diabetic rats normalized heparin-releasable lipoprotein lipase activity in perfused hearts, but the depressed lipoprotein lipase activity in cardiomyocytes from diabetic hearts was unchanged by in vivo thyroid hormone treatment. However, hypothyroidism in thyroidectomized rats did not alter lipoprotein lipase activity in either perfused hearts or isolated cardiomyocytes. Therefore, thyroid hormones may interact with some other factor(s) in this acute, insulin-deficient model of diabetes to selectively regulate functional, heparin-releasable lipoprotein lipase activity in perfused hearts.

Animals↗

PubMed1986

Lipoprotein lipase-suppressing mediator in serum of endotoxin-treated rats.

The conditions under which lipoprotein lipase-suppressing mediator is present in serum of endotoxin-treated rats was determined in this study. The suppression of lipoprotein lipase activity in 3T3-L1 cells was used as a bioassay for mediator in serum. Endotoxin (0.1-10 micrograms/ml) and serum from control rats did not suppress lipoprotein lipase activity. Maximum suppression of cell lipoprotein lipase activity (70%) by serum from endotoxic rats required a cell exposure time of 5 h. At the highest dose of endotoxin used (1 mg/100 g), significant suppression was achieved when cells were incubated with 0.5% serum from endotoxic rats (P less than 0.05). Serum obtained 2-3 h after endotoxin injection possessed the maximal ability to suppress lipase activity, but suppressing activity was not present in serum collected 8 h after endotoxin. Rats rendered tolerant to endotoxin by 5 daily injections (0.1 mg/100 g) did not contain detectable levels of mediator in serum after endotoxin injection. The results demonstrate that the presence of lipoprotein lipase activity-suppressing mediator is transitory after in vivo exposure of naive rats to endotoxin, but does not appear in serum of endotoxin tolerant rats.

Animals↗

PubMed1987

Influence of apolipoprotein E on soluble and heparin-immobilized hepatic lipase.

The effect of human apolipoprotein E (apoE), either alone or in combination with apoC, on the lipolysis of a radiolabeled triglyceride emulsion was studied with hepatic lipase in solution and immobilized on heparin-Sepharose. The soluble hepatic lipase was inhibited, whereas the heparin-immobilized lipase was stimulated by apoE. This stimulation was attenuated by combining apoE with either apoC-II or C-III. The heparin-immobilized lipase demonstrated much less lipolysis of the zwitterionic phosphatidylcholine-stabilized triglyceride emulsion than did the soluble enzyme. This difference was less when the emulsion was stabilized by a nonionic detergent. apoE inhibited lipase activity when assayed under conditions (0.4 M NaCl) of bound enzyme and unbound substrate. Increasing the emulsion apoE content beyond optimum inhibited lipolysis by the immobilized enzyme. Kinetic analysis of phosphatidylcholine-stabilized triglyceride emulsions revealed a significant decrease in immobilized enzyme Km and an increase in Vmax when the emulsion was supplemented with apoE. Distributing the immobilized lipase in clustered aggregates produced more lipolysis than when the same enzyme content was uniformly bound.

Animals↗