Showing papers on "Lipase published in 1982"

Serum triglycerides determined colorimetrically with an enzyme that produces hydrogen peroxide.

Abstract: In this direct colorimetric procedure, serum triglycerides are hydrolyzed by lipase, and the released glycerol is assayed in a reaction catalyzed by glycerol kinase and L-alpha-glycerol-phosphate oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is monitored in the presence of horseradish peroxidase with 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone as the chromogenic system. The high absorbance of this chromogen system at 510 nm affords useful results with a sample/reagent volume ratio as low as 1:150, and a blank sample measurement is not needed. A single, stable working reagent is used; the reaction is complete in 15 min at room temperature. The standard curve is linear for triglyceride concentrations as great as 13.6 mmol/L. Average analytical recovery of triglycerides in human sera is 100.1%, and within-run and between-run precision studies showed CVs of less than or equal to 1.6 and less than or equal to 3.0%, respectively. The method is suitable for automation.

Insulin stimulation of adipose tissue lipoprotein lipase. Use of the euglycemic clamp technique.

Abstract: The role of insulin in the regulation of adipose tissue lipoprotein lipase activity in humans was investigated in 11 normal subjects and compared with the effects of 0.9% saline infusions in five control subjects. After a basal adipose tissue biopsy for lipoprotein lipase activity, insulin was rapidly infused to achieve and maintain serum levels of approximately 70 microunits/ml while plasma glucose was kept at basal concentrations. Free fatty acids in serum fell to 27 +/- 3% of basal by 20 min (t = 5.19, P less than 0.001) and triglycerides decreased to 77 +/- 3% of basal by 80 min (t = 3.76, P less than 0.01). Adipose tissue lipoprotein lipase activity failed to increase significantly above that measured in controls by the first 3 h of the study. By 6 h of the infusion a stimulatory effect of insulin on adipose tissue lipoprotein lipase was found (t = 3.94, P less than 0.01). There was no relationship between the amount of glucose infused and the insulin effect on the enzyme. The increase in adipose tissue lipoprotein lipase activity at 6 h, however, was inversely related to the basal lipase activity (r = -0.690, P less than 0.02). Thus, insulin appears to stimulate adipose tissue lipoprotein lipase activity in humans. This effect of insulin is delayed when compared with antilipolysis and the fall in plasma triglyceride. The inverse relationship between insulin-stimulated adipose tissue lipoprotein lipase activity and basal enzyme activity suggests that adipose tissue itself is the main regulator of the lipase response to insulin.

Lipoprotein lipase suppression in 3T3-L1 cells by an endotoxin-induced mediator from exudate cells

Abstract: Conditioned medium from cultures of mouse peritoneal exudate cells incubated wih endotoxin contains a mediator that markedly suppresses (greater than 90%) lipoprotein lipase (triacylglycero-protein acylhydrolase, EC 3.1.1.34) activity in differentiating 3T3-L1 mouse preadipocytes. The effect is dependent upon the amount of mediator and is evident as early as 30 min after the addition of the mediator-containing medium to 3T3-L1 cell cultures. Neither endotoxin nor conditioned medium from cultures of exudate cells not exposed to endotoxin shows the presence of the mediator. Lysates of the exudate cells are also unable to suppress the lipase activity. Increasing the amount of insulin does not reverse this suppression, even at 1000 times the concentration used for standard experiments. The lipoprotein lipase suppression mediator present in the conditioned medium of endotoxin-treated exudate cells is heat labile and has an apparent molecular weight of at least 12,000. The mediator does not inhibit lipoprotein lipase activity directly nor does it affect the half-life of enzyme activity released in the medium. The present study demonstrates that endotoxin promotes the release of a mediator from exudate cells that suppresses the activity of lipoprotein lipase in 3T3-L1 preadipocytes.

Application of immobilized lipase to regio-specific interesterification of triglyceride in organic solvent

Abstract: Lipase from Rhizopus delemar was immobilized by entrapment with photo-crosslinkable resin prepolymers or urethane prepolymers or by binding to various types of porous silica beads. The immobilized lipase preparations thus obtained were examined for their activity in converting olive oil to an interesterified fat (cacao butter-like fat), whose oleic acid moieties at 1- and 3-positions were replaced with stearic acid moieties, in the reaction solvent n-hexane. Although all of the immobilized preparations exhibited some activity, lipase adsorbed on Celite and then entrapped with a hydrophobic photo-crosslinkable resin prepolymer showed the highest activity, about 75% of that of lipase simply adsorbed onto Celite. Entrapment markedly enhanced the operational stability of lipase.

Lipoprotein lipase secretion by human monocyte-derived macrophages.

Abstract: Human monocyte-derived macrophages in culture produced lipoprotein lipase. Although freshly isolated blood monocytes did not secrete much lipase activity, 1 d in culture was sufficient to trigger measureable enzyme production. During 3 wk in culture, maximal activity was attained after 7 d. At all times, the culture medium contained more enzyme activity than did a serum-heparin eluate or a detergent extract of the cell layer. The lipase activity was stimulated by serum and was inhibited by preincubation with antiserum to bovine lipoprotein lipase or when assayed at a high salt concentration. Furthermore, the enzyme bound to a heparin-Sepharose affinity column at physiological ionic strength. Cells cultured from a subject with primary lipoprotein lipase deficiency secreted no detectable enzyme. Since macrophages are prominent components of atherosclerotic lesions in man, their ability to synthesize and secrete lipoprotein lipase may be important to atherogenesis.

Direct evidence that cholesterol ester hydrolase from adrenal cortex is the same enzyme as hormone-sensitive lipase from adipose tissue.

Abstract: Several properties of the cytosolic cholesterol ester hydrolase from bovine adrenal cortex were investigated and those properties were compared directly with those of the well-characterised hormone-sensitive lipase, the rate-limiting enzyme in adipose tissue lipolysis. Properties examined included: (a) activity against different substrates; (b) susceptibility to inhibition by NaF, Hg2+ ions and diisopropyl fluorophosphonate; (c) subunit molecular weight as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate; (d) ability to serve as a substrate for cyclic AMP-dependent protein kinase; (e) effect of phosphorylation on enzyme activity; and (f) degradation pattern of polypeptides following limited proteolysis. In all respects the two enzymes exhibited essentially identical characteristics. It is therefore concluded that the same protein, or two very similar proteins, catalyses the hydrolysis of cholesterol esters in adrenal cortex and lipolysis in adipose tissue. The implication of this finding is discussed in relation to the hormonal control of steroidogenesis in adrenal cortex and of lipolysis in adipose tissue.

Digestion of human milk lipids: physiologic significance of sn-2 monoacylglycerol hydrolysis by bile salt-stimulated lipase.

Abstract: The bile salt-stimulated lipase secreted with human milk was found to be devoid of positional specificity, i.e., it hydrolyzed emulsified triacylglycerols to glycerol and fatty acids. It also hydrolyzed micellar sn-2 monoacylglycerols. This is in contrast to pancreatic lipase which has a pronounced preference for hydrolysis of sn-1 and sn-3 ester bonds. When the two enzymes were operating together, as in the intestine of the infant fed raw human milk, the sn-2 monoacylglycerols formed by pancreatic lipase served as an excellent substrate for bile salt-stimulated lipase. Thus, the end products of triacylglycerol hydrolysis became glycerol and fatty acids and not sn-2 monoacylglycerol and fatty acids. The bile salt-stimulated lipase also catalyzed incorporation of fatty acids into acylglycerols to a much lesser extent than did pancreatic lipase. Together these two effects of bile salt-stimulated lipase have a promoting effect on the overall process of intraluminal lipolysis. In newborn infants, with low intraduodenal bile salt concentrations, glycerol and fatty acids also should be more readily absorbed than monoacylglycerol and fatty acids. Thus, by serving as a complement to pancreatic lipase, bile salt-stimulated lipase can ensure efficient utilization of milk lipids also in infants with immature endogenous mechanisms for fat digestion and absorption.

Neutrophil chemotaxis by Propionibacterium acnes lipase and its inhibition.

Abstract: The chemoattraction of Propionibacterium acnes lipase for neutrophils and the effect of lipase inhibitor and two antibiotic agents on the chemotaxis were evaluated. Of the various fractions tested, partially purified lipase (fraction 2c) was the most active cytotaxin produced by P. acnes. Serum mediators were not required for the generation of chemotaxis by lipase in vitro. Diisopropyl phosphofluoridate at low concentration (10(-4) mM) completely inhibited lipase activity as well as polymorphonuclear leukocyte chemotaxis generated by lipase. Tetracycline hydrochloride and erythromycin base at concentrations of 10(-1) mM and 1 mM, respectively, caused 100% inhibition of PMN migration toward lipase or zymosan-activated serum. The inhibiting activity of the antibiotics was directed against cells independently of any effect on lipase. Chemotaxis by P. acnes lipase suggests a wider role for this enzyme in the inflammatory process and the pathogenesis of acne vulgaris.

Purification and Some Properties of Cell-bound Lipase from Saccharomycopsis lipolytica

Abstract: Two kinds of cell-bound lipases were purified from S. lipolytica with a total recovery of 8%. One was adsorbed and the other not to CM-Sepharose CL-6B at pH 5.0. The method of purification involved chromatography on CM-Sepharose CL-6B, DEAE-Sepharose CL-6B and Sephadex G-100 columns. Sodium dodecylsulfate-polyacrylamide gel electrophoresis of the purified lipases gave a single band. The purified Upases required an activator, such as oleic acid for hydrolysis of triglycerides. The Upases hydrolyzed tricaprylin at the largest initial rate and the optimum pH for hydrolysis of olive oil was about 8.0 under the experimental conditions. They were stable for 20 min below 37°C and in a pH range from 4.5 to 8.0 for 22 hr at 5°C. The molecular weight of Lipase I and II was estimated to be 39,000 and 44,000, respectively, and both Upases were a monomeric enzyme.

Reversal of decreased hepatic lipase and lipoprotein lipase activities after treatment of hypothyroidism.

Abstract: Plasma lipoprotein concentrations, activities of hepatic lipase and lipoprotein lipase in post-heparin plasma, and the removal rate of exogenous triglyceride were measured in fourteen patients with severe primary hypothyroidism before and after 4 months substitution therapy with 1-thyroxine. Before treatment plasma LDL cholesterol concentrations were markedly increased while HDL cholesterol and plasma triglycerides were in the upper reference range. Thyroxine substitution led to a normalization of LDL cholesterol in all patients. Plasma triglycerides and HDL cholesterol decreased moderately. Hepatic lipase and lipoprotein lipase activities were initially reduced but increased significantly after treatment, by about 170% and 55%, respectively. The increase in hepatic lipase activities was significantly correlated to the increase in serum triiodothyronine levels and also to the reduction in LDL cholesterol concentrations. The decrease in LDL cholesterol was also significantly correlated to the increase in serum triiodothyronine concentration. In two patients initially treated with triiodothyronine, the activity of hepatic lipase, but not that of lipoprotein lipase, increased after 24 and 48 h, while LDL cholesterol levels decreased substantially. We suggest that the reduced activities of hepatic lipase as well as of lipoprotein lipase are important pathogenetic factors for the dyslipoproteinaemia occurring in hypothyroidism and that the low serum triiodothyronine concentration is of major importance for the alterations in lipid transport.

Isolated co-lipase deficiency in two brothers.

Abstract: Two normally developed Assyrian brothers with isolated pancreatic co-lipase deficiency are described. They presented at the age of 5-6 years with loose stools. They had steatorrhoea, and analysis of exocrine pancreatic enzymes in the small intestine showed co-lipase deficiency, while amylase, chymotrypsin, trypsin and lipase were normal. Intraduodenal infusion of purified co-lipase improved fat digestion measured by the triolein breath test. Their steatorrhoea diminished on treatment with enteric-coated pancreatic enzymes.

The lipolytic triad: human lingual, breast milk, and pancreatic lipases: physiological implications of their characteristics in digestion of dietary fats.

Abstract: The characteristics of human lingual, breast milk, and pancreatic lipases as related to the digestion of dietary fats in infants are discussed. The activity and specificity of these enzymes and structure of the dietary fats largely determine the rates of lipolysis, the types of digestion products formed, and the rates of absorption. Also possibly influenced are micelle formation, intestinal health, breast milk jaundice, and the absorption of other nutrients. In premature infants, the action of lingual and breast milk lipase are particularly important in the absorption of dietary fatty acids.

Colipase and maximally activated pancreatic lipase in normal subjects and patients with steatorrhea.

Abstract: A B S T R A C T Human pancreatic lipase in duodenal secretions was studied under conditions of maximal activation by porcine colipase and maximal inhibition by sodium taurodeoxycholate. In almost all samples, total lipase activity in 4mM sodium taurodeoxycholate was activated by the addition of porcine colipase. Activation was linear until saturation by cofactor was reached, and maximum activity was greater than that obtained in the absence of bile salts. At pH 8.0 in 4 mM sodium taurodeoxycholate, lipase activity was due to pancreatic lipase in samples from normal and steatorrheic individuals and was proportional to the concentration of endogenous colipase in samples that could be activated by exogenous colipase. In these samples, therefore, colipase activity could be conveniently assayed as the lipase activity at pH 8.0 in 4mM sodium taurodeoxycholate. Colipase to total pancreatic lipase ratios varied widely from individual to individual and on average were significantly lower in steatorrheic patients. In individual samples, colipase secretion was stimulated by pancreozymin and secretin roughly in parallel with total pancreatic lipase, but some variation in the ratio of the two was often seen in successive collection periods. Because pancreatic lipase is usually unsaturated with respect to cofactor, lipolytic activity in duodenal secretions may be finely controlled by modulation of colipase secretion.

In vitro Inhibition of Pancreatic Enzyme Activities by Dietary Fiber

Abstract: Trypsin, amylase, lipase and phospholipase activities were assayed in buffer solutions and in human duodenal juice after incubation with different types of dietary fiber. In buffer solutions, trypsin

Asymmetric Hydrolysis of (±)-1,2-Diacetoxy-3-chloropropane and Its Related Compounds with Lipase. Synthesis of Optically Pure (S)-Propranolol

Abstract: Asymmetric hydrolysis of (±)-1,2-diacetoxy-3-chloropropane (1) with a very small amount of a lipoprotein lipase gave (S)-1 of 90% enantiomeric excess (e.e.). Reactions of (S)-1 with phenols in an alkaline condition yielded the corresponding (S)-3-aryloxy-1,2-propanediols. From (S)-3-(1-naphthoxy)-1,2-propanediol (5) was synthesized the optically pure (S)-isomer of propranolol [1-isopropylamino-3-(1-naphthoxy)-2-propanol] (9), one of the ²-adrenergic blocking agents. Hydrolysis of (±)-1,2-diacetoxy-3-bromopropane (11) and (±)-1,2-diacetoxyethylbenzene (12) with the lipase afforded (S)-11 of 77% e.e. and (R)-12 of 73% e.e., respectively.

Response of the exocrine pancreas to quantitative and qualitative variations in dietary lipids.

Abstract: In the rat, pancreatic amylase and, to a lesser extent, lipase adapt quantitatively to the amount of their respective substrates in the diet by an increase in specific activity and total contents (range of variation, fivefold for amylase and twofold for lipase). Colipase responded to protein intake (r = 0.85, P less than 0.01) and not to lipids provided protein intake was below 3.5 g or above 6.0 g. With this latter amount of protein, a maximal level was obtained, even with 2% lipid in the diet. Between 3.5 and 6.0 g, lipid intake was found to modulate colipase in parallel with lipase. When different types of fat were compared, the degree of saturation was found to have no impact on lipase, colipase, and amylase. Diets containing medium-chain triglycerides (C8-C10) did not maximally increase specific activity and total content of lipase and colipase, whereas they did not repress amylase as much longer chain triglycerides did. With coconut oil (45% C12), lipase was maximally stimulated but amylase was not maximally repressed, showing that the regulation of the hydrolases may be partly reciprocal and partly independent.

Effects of oestradiol and levonorgestrel on lipoprotein lipids and postheparin plasma lipase activities in normolipoproteinaemic women.

Abstract: The effects of oestradiol and levonorgestrel on plasma lipoprotein cholesterol (Chol) and triglyceride (Tg) levels and on postheparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activity were studied in 52 normolipoproteinaemic women. The androgen-derived progestin levonorgestrel increased postheparin plasma hepatic lipase (PH-HL) activity and decreased plasma high-density lipoprotein (HDL) lipid concentrations in a manner opposite to that of oestradiol. The relationships between PH-HL activity and HDL lipids suggest an important role for this enzyme as a mediator of sex hormone action on HDL.

Stereospecificity of premature human infant lingual lipase

Abstract: The lingual lipase in gastric aspirates from premature infants was found to be partially stereospecific forsn-3 esters of synthetic enantiometric triacylglycerols containing 18∶1 and 16∶0 Thesn-3 ester was hydrolyzed about 4 times faster than the acid at thesn-1 position with no difference in rates between 18∶1 and 16∶0 Thesn-2 was also hydrolyzed to some extent

Extracellular Enzymatic Activities in Aureobasidium Pullulans

Abstract: One hundred and ninety-eight strains of Aureobasidium pullulans were screened for their ability to release extracellular hydrolytic enzymes into the cutural medium. Most of the isolates produced, to a varying extent, enzymes such as amylase, lipase (with different fats as substrates), protease (as caseinolysis and gelatin liquefaction), nucleases (ribonuclease and deoxyribonuclease), urease, and phosphatase. Neither cellulase nor chitinase were produced. Since some enzymes showed a high level of activity, A. pullulans could possibly be considered a promising source of extracellular lytic enzymes.

Hochempfindlicher Enzymimmunoassay zur Bestimmung von Human-Pankreas-Lipase

Abstract: A highly sensitive and specific enzyme immunoassay for the determination of pancreatic lipase is described. The test follows the sandwich principle; total incubation time is 4.5 hours at 20--25 degrees C. Lipase concentrations between 3 and 300 micrograms/1 can be quantified (sample dilution 1 + 10); the lower detection limit is 0.3 micrograms/1 (sample dilution 1 + 1). Coefficients of variation from 2.9 to 6.5% for the in batch precision, and from 4.4 to 10.5% for the day-to day precision were found. A reference range from 7.7 to 56 micrograms/1 was calculated from the lipase concentrations in 369 serum samples from healthy adults (2.5 th--97.5 th percentile, median 23 micrograms/1). Very low concentrations were found in cord blood (median 2.8 micrograms/1). The lipase level remains quite constant between the ages of 3 and 50 years (median 15--20 micrograms/1); at the age of 70 years a median of 26 micrograms/1 is reached.

Involvement of glyoxysomal lipase in the hydrolysis of storage triacylglycerols in the cotyledons of soybean seedlings.

Abstract: The total cotyledon extract of soybean (Glycine max [L.] Merr. var. Coker 136) seedlings underwent lipolysis as measured by the release of fatty acids. The highest lipolytic activity occurred at pH 9. This lipolytic activity was absent in the dry seeds and increased after germination concomitant with the decrease in total lipids. Using spherosomes (lipid bodies) isolated from the cotyledons during the peak stage of lipolysis (5-7 days) as substrates, about 40% of the lipase activity was found in the glyoxysomes after organelle breakage had been accounted for; the remaining activity was distributed among other subcellular fractions but none was found in the spherosomal fraction. The glyoxysomal lipase had maximal activity at pH 9, and catalyzed the hydrolysis of tri-, di-, and monoacylglycerols of linoleic acid, the most abundant fatty acid in soybean. The spherosomes contained a neutral lipase that could hydrolyze monolinolein and N-methylindoxylmyristate, but not trilinolein. This spherosomal lipase activity dropped off rapidly during early seedling growth, preceding lipolysis. Spherosomes isolated from either dry or germinated seeds did not possess lipolytic activity, and spherosomes from germinated seeds but not from dry seeds could serve as substrates for the glyoxysomal lipase. It is concluded that the glyoxysomal lipase is the enzyme catalyzing the initial hydrolysis of storage triacylglycerols.

Postheparin plasma lipoprotein lipase in copper-deficient rats.

Abstract: Postheparin plasma lipoprotein lipase has been investigated in male sprague-Dawley rats fed a diet deficient in copper. Deficiency was verified by the detection of anemia, hypercholesterolemia and decreased myocardial copper. Three experiments were done; they showed significant decrease in enzyme activity (40-47% reduction) in deficiency. Copper may be required for the formation of the activator complex of the enzyme. Decreased lipoprotein lipase activity may be responsible for the hypertriglyceridemia of copper deficiency, and that may also explain its hypercholesterolemia.

Effects of dexamethasone on pancreatic tissue and on serum amylase and lipase activities in dogs.

Abstract: The effects of dexamethasone on the pancreas and on pancreatic amylase and lipase activities were determined in clinically normal dogs and in dogs with neurologic disease. Dexamethasone increased serum lipase activity without any histologic damage to the pancreas in either group of dogs. It decreased serum amylase activity in the normal dogs and had a variable effect in dogs with neurologic disease, with or without confirmed pancreatitis. It was suggested that high serum lipase activity in dexamethasone-treated dogs may not be attributable to pancreatitis and that the reasons are still unknown. It was concluded that high serum lipase activity is an unreliable basis for diagnosis of pancreatitis in dogs treated with dexamethasone. The data allowed no conclusion about an additive effect of dexamethasone and neurologic disease causing pancreatitis.