Showing papers on "Lipase published in 1975"
TL;DR: Solid media are described on which the production of the extracellular enzymes amylase, lipase, DNA- and RNAase, pectinase, protease, urease, and chitinase were detected.
Abstract: Solid media are described on which the production of the extracellular enzymes amylase, lipase, DNA- and RNAase, pectinase, protease, urease, and chitinase were detected. The media were tested with...
644 citations
TL;DR: Defects in insulin secretion, both in postabsorptive and postprandial states, are associated with low adipose tissue lipoprotein lipase and may lead to hypertriglyceridemia in diabetic man.
Abstract: The role of insulin in the regulation of human adipose tissue lipoprotein lipase was evaluated. Adipose tissue heparin-releasable lipoprotein lipase (thought to be related to peripheral clearance of plasma triglycerides) was low in insulin-deficient, untreated hyperglycemic diabetic subjects (P less than 0.001) and treatment of hyperglycemia returned the activity to normal. In chronic hyperinsulinism, represented by obesity, heparin-releasable activity among control subjects was correlated to percent of ideal body weight (r=0.53, P less than 0.05) and to fat cell size (r=0.61, P less than 0.02). Acetone-ether powder lipoprotein lipase activity (presumed to reflect total tissue enzyme) was also related to percent of ideal body weight (r=0.76, P less than 0.001 for controls; r=0.67, P less than 0.05 for diabetics) and to fat cell size (r=0.71, P less than 0.01 for controls; r=0.85, P less than 0.01 for diabetics. Postprandial-stimulated insulin secretion was related to diet-induced changes in lipoprotein lipase in control subjects; both were dependent upon the amount of dietary carbohydrate. In contrast, the diabetic patients with low insulin responses, failed to increase lipoprotein lipase activity with feeding. The changes in heparin-releasable (r=0.66, P less than 0.01) and acetone-ether powder (r=0.69, P less than 0.01) activity during feeding were related to the percent increase in plasma insulin. Thus, insulin appears to be important in the regulation of human adipose tissue lipoprotein lipase activity. Elevated insulin levels in obesity and increased insulin secretion after eating were associated with increased lipoprotein lipase activity. Defects in insulin secretion, both in postabsorptive and postprandial states, are associated with low adipose tissue lipoprotein lipase and may lead to hypertriglyceridemia in diabetic man.
308 citations
TL;DR: The optimal conditions for the determination of the two postheparin plasma triglyceride hydrolases were shown to be similar to those described for the purified enzymes, making the methods suitable for studies of patients with various hyperlipidemias.
308 citations
TL;DR: The constancy of the ratio of activities after isoelectric focusing and during thermal deactivation indicates that this enzyme has hydrolase activity against both triglycerides and phospholipids.
202 citations
TL;DR: It is suggested that the rise in blood triglyceride concentrations, which accompanies high palsma estrogen levels, could be due to the marked inhibition of adipose tissue lipoprotein lipase activity.
Abstract: The effect of 17beta-estradiol or progesterone administration on adipose tissue lipoprotein lipase activity was studied in male and ovariectomized female rats. Lipoprotein lipase activity was measured in acetone-ether-extracted preparations of adipose tissue with doubly labeled (14C-fatty acid, 3H-glyceryl) chylomicron triglyceride as substrate. Administration of 17beta-estradiol to male rats lowered adipose tissue lipoprotein lipase activity from 8.22 plus or minus 1.8 U/g (1 U = 1 mumol triglyceride hydrolyzed per h) to 4.96 plus or minus 0.5 U/g in the treated group. Ovariectomy increased adipose tissue lipoprotein lipase activity from 10.4 plus or minus 1.8 U/g in controls to 22.7 plus or minus 4.3 U/g. 17beta-Estradiol administration to ovariectomized rats cuased a marked fall in adipose tissue lipoprotein lipase activity: 17beta-estradiol (2.5 mug/day) lowered the enzyme activity to 9.00 plus or minus 1.2 U/g, whereas 25 mug/day further decreased lipoprotein lipase activity to 3.2 plus or minus 0.6 U/g. Blood triglyceride levels increased from 0.8 plus or minus 0.05 mumol/ml in ovariectomized rats to 1.4 plus or minus 0.09 mumol/ml in 25 mug/day 17beta-estradiol-treated rats. Progesterone administration did not affect adipose tissue lipoprotein lipase activity in either male or ovariectomized rats. Heart and lung lipoprotein lipase activity was unaffected by hormone treatment. We suggest that the rise in blood triglyceride concentrations, which accompanies high palsma estrogen levels, could be due to the marked inhibition of adipose tissue lipoprotein lipase activity.
173 citations
TL;DR: Kinetic data indicate that the binding between colipase and lipase in the presence of substrate is strong and occurs in an approximately stoichiometric relationship, suggesting that lipase binds to hydrophobic interfaces with partial irreversible inactivation.
170 citations
TL;DR: It is concluded that oxandrolone increases the activities of postheparin plasma hepatic lipase and phospholipase A1 but has little influence on lipoprotein lipase.
Abstract: The effect of a synthetic steroid, oxandrolone, on total postheparin plasma lipolytic activity, postherpain hepatic lipase activity, lipoprotein lipase and phospholipase A1 was studied in seven patients with hypertriglyceridemia. The mean total postheparin lipolytic activity increased 100 per cent during oxandrolone tratement (p smaller than 0.05). This change was caused mainly by postheparin hepatic lipase, whose activity increased on the average more than 2.5 times (p smaller than 0.001). The change in postheparin plasma-lipoprotein-lipase activity was insignificant. A highly significant correlation (r equals +0.87, p smaller than 0.01) was observed between the activities of postheparin hepatic lipase and phospholipase A1 before and during oxandrolone treatment. No relation was observed between serum triglyceride level and various postheparin lipase activities, or between the changes induced by oxandrolone in the level of serum lipids and the activities of postheparin lipases. We conclude that oxandrolone increases the activities of postheparin plasma hepatic lipase and phospholipase A1 but has little influence on lipoprotein lipase.
128 citations
TL;DR: In the absence of bile salts, the enzyme has no activity against milk fat or against emulsified trioleylglycerol, but it was found to be active at pH 3.5 and 37 degrees C for 1 hour as discussed by the authors.
Abstract: Human milk contains a bile salt-stimulated lipase in amounts that, at pH 6.5 and in the presence of bile salts, might account for a total hydrolysis of the milk triacylglycerols in less than 30 min. In the absence of bile salts the enzyme has no activity against milk fat or against emulsified trioleylglycerol. The primary bile salts sodium cholate and sodium chenodeoxycholate and their taurine and glycine conjugates, but not the secondary bile salt sodium deoxycholate or its taurine and glycine conjugates, caused a pronounced activation of the enzyme against emulsified trioleylglycerol. The lipase was stable at pH 3.5 and 37 degrees C for 1 hour. It was inactivated when incubated with trypsin or chymotrypsin at pH 6.5 but these inactivations were almost abolished in the presence of bile salts. High concentrations of pepsin slowly inactivated the enzyme at pH 4.0. The bile salt-stimulated lipase in human milk is thus stable enough to be active in the intestine, and it is present in high enough activity to contribute significantly to the hydrolysis of the milk triaclyglycerols in the intestine.
114 citations
TL;DR: The physiological specificity of fat digestion in several species of marine fish was studied by incubating a variety of synthetic and natural lipid substrates in fish intestinal fluid with wide variation in the ratio occurred among different batches of intestinal juice.
Abstract: The physiological specificity of fat digestion in several species of marine fish was studied by incubating a variety of synthetic and natural lipid substrates in fish intestinal fluid. Wax ester and triglyceride hydrolyses were studied in vivo and in vitro. In vivo feeding studies showed triglyceride hydrolyses and reesterification in the gut occurred 4 times faster than wax ester metabolism. In vitro comparisons of wax and triglyceride lipolysis always showed triglycerides to be hydrolyzed faster than wax esters; however, wide variation in the ratio occurred among different batches of intestinal juice. Ca. 50% of the 2-monoglycerides formed in the lipolytic sequence were hydrolyzed. Esters of lipase resistant fatty acids (20∶4 and 20∶5) were cleaved faster than normal fatty acid esters (18∶2 and 18∶3). Two of the species studied, the northern anchovy,Engraulis mordax and the jack mackerel,Trachurus symmetricus, empty lipase(s) into their gall bladders and produce phospholipid-free bile.
111 citations
TL;DR: It is shown that lipase, which readily adsorbs to hydrophobic interfaces, requires colipase for its adsorption to interfaces coated with an amphipath or possessing themselves an hydrophilic character.
108 citations
TL;DR: Methods for the determination of pancreatic lipase in small intestinal content have been re-evaluated in the light of the presence of co-lipase therein and a simple diagnostic criterion is given to detect a possible specific co- Lipase deficiency.
Abstract: Methods for the determination of pancreatic lipase in small intestinal content have been re-evaluated in the light of the presence of co-lipase therein A method is described for the determination of co-lipase in intestinal content based on its property to reactivate bile-salt-inhibited lipase Figures are given for lipase and co-lipase activities in intestinal contents of normal humans aged 1-22 These two components originating in the pancreatic juice vary in a parallel fashion, and no variations with age were apparent A simple diagnostic criterion is given to detect a possible specific co-lipase deficiency
TL;DR: The serum- Stimulated lipase in bovine milk has immunological determinants in common with the serum-stimulated lipases in human milk and in human postheparin plasma.
TL;DR: The catalytic rate of membrane-supported lipoprotein lipase has been determined for chylomicron and very low density lipop protein substrates during the formation of triglyceride-depleted ("remnant") particles and both lipop Protein species and their generated remnant products were competitive substrates for lipase activity.
Abstract: The catalytic rate of membrane-supported lipoprotein lipase has been determined for chylomicron and very low density lipoprotein substrates during the formation of triglyceride-depleted ("remnant") particles. Both lipoprotein species and their generated remnant products were competitive substrates for lipase activity. Remnant formation from each species was associated with decreasing kc but an unchanged apparent Km. This finding was confirmed from the rate of plot of total triglyceride catabolism by lipase at low substrate concentrations. When compared with the major very low density lipoprotein fraction (Sf 100-400), a fraction isolated from plasma with a lower flotation rate (Sf 40-100) had a lipid composition and decreased kc compatible with this representing a physiological remnant particle.
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TL;DR: The bile salt‐stimulated lipase in human milk is stable enough to be active in the intestine, and it is present in high enough activity to contribute significantly to the hydrolysis of the milk triaclyglycerols in the intestines.
Abstract: . Human milk contains a bile salt-stimulated lipase in amounts that, at pH 6. 5 and in the presence of bile salts, might account for a total hydrolysis of the milk triacylglycerols in less than 30 min. In the absence of bile salts the enzyme has no activity against milk fat or against emulsified trioleylglycerol. The primary bile salts sodium cholate and sodium chenodeoxycholate and their taurine and glycine conjugates, but not the secondary bile salt sodium deoxycholate or its taurine and glycine conjugates, caused a pronounced activation of the enzyme against emulsified trioleylglycerol. The lipase was stable at pH 3. 5 and 37°C for 1 hour. It was inactivated when incubated with trypsin or chymotrypsin at pH 6. 5 but these inactivations were almost abolished in the presence of bile salts. High concentrations of pepsin slowly inactivated the enzyme at pH 4. 0. The bile salt-stimulated lipase in human milk is thus stable enough to be active in the intestine, and it is present in high enough activity to contribute significantly to the hydrolysis of the milk triaclyglycerols in the intestine.
TL;DR: The authors concluded that the socalled acid shift of the optimal pH for lipase action described earlier is due to the low adsorption rate of lipase on its substrate at alkaline pH rather than to a change of the pH dependence of the V(max) and K(m) of the enzyme.
TL;DR: The Michaelis constant of the stainless steel–lipase was found to be equal to that of the free enzyme, suggesting that adsorption and subsequent crosslinking does not alter the enzyme–substrate affinity.
Abstract: Pancreatic lipase has been immobilized onto stainless steel beads by adsorption followed by crosslinking, and onto polyacrylamide by covalent bonding. The activities of the two types of immobilized enzyme toward the particulate substrate, tributyrin emulsion droplets, were determined experimentally, and rate constants based on Michaelis-Menten kinetics were calculated. The activity of the stainless steel-lipase was determined for various flow conditions and for various support sizes by the use of a differential fluidized bed recycle reactor. The rate constants calculated indicate that the experimental reaction rate is free from mass transfer influences, since the observed Michaelis constant does not vary with the fluidization velocity or with the support particle size. In addition, the Michaelis constant of the stainless steel-lipase was found to be equal to that of the free enzyme, suggesting that adsorption and subsequent crosslinking does not alter the enzyme-substrate affinity. The emulsion substrate mass transfer rates, calculated from the filtration theory, indicate that each substrate particle which contact the immobilized enzyme is hydrolyzed to a significant extent. The experimentally determined kinetic rate constants may be used directly to predict the size of integral fluidized bed reactors.
TL;DR: An enzymatic method for determing serum triglycerides (triacylglycerols) is described, adapted to a centrifugal analyzer, and yields satisfactory results with regard to precision, accuracy, and insensitivity to interferences.
Abstract: I describe an enzymatic method for determing serum triglycerides (triacylglycerols). The triglycerides are hydrolyzed by a mixture of lipase and esterase. The glycerol released is determined by kinetic fixed-time analysis, with use of glycerol kinase, pyruvate kinase, and lactate dehydrogenase. Through addition of the competitive inhibitor ATP the Michaelis constant of pyruvate kinase is apparently increased, considerably extending the linearity of the assay. There is no need for serum blanks or reagent blanks. The method has been adapted to a centrifugal analyzer (the ENI GEMSAEC). It yields satisfactory results with regard to precision, accuracy, and insensitivity to interferences.
TL;DR: Acinetobacter O16, a psychrophilic species, produced extracellular lipase (measured by hydrolysis of olive oil, tributyrin, or beta-naphthyl laurate) when grown on a complex medium (peptone plus yeast extract) and lipase formation was greatly affected by nutrient conditions.
Abstract: Acinetobacter O16, a psychrophilic species, produced extracelullar lipase (measured by hydrolysis of olive oil, tributyrin, or β-naphthyl laurate) when grown on a complex medium (peptone plus yeast...
TL;DR: The purified lipase preparation from Mucor javanicus exhibits phospholipase A1 activity, hydrolyzing the carboxyl ester at the 1-position of phosphatidylcholine, and this activity seems to be due to the action of the lipase itself and not due to any other specificospholipases.
TL;DR: It is shown that the palmitoyl-CoA hydrolase activity of postheparin serum of the rat is mainly derived from the liver, and the proposed mechanism for the role of extrahepatic lipoprotein lipase in atherogenesis is discussed.
TL;DR: It is suggested that in bovine milk there is only one major lipase and that it is identical to lipoprotein lipase.
Abstract: The lipoprotein lipase and tributyrate hydrolysing activities were found to be similarly distributed in the fractions obtained when whole milk was separated into skim-milk and cream, and when the cream was washed and freed from lipid. These enzyme activities in skim-milks and in extracts of lipid-free cream could not be separated by affinity chromatography on heparin-Sepharose. The enzymes were inactivated to the same degree when incubated at 37°C in the presence of 1·5 M-NaCl, pH 8·5, and both showed the same marked decrease in stability at 4°C in 1·5 M-NaCl, when the pH was changed from 8·3 to 9·0. Irradiation of skim-milk with UV-light caused the same decrease in both lipoprotein lipase and tributyrate hydrolysing activities. An antiserum against a highly purified skim-milk lipoprotein lipase caused total inhibition of the lipoprotein lipase and tributyrate hydrolysing activities in skim-milk and in extracts of lipid-free cream. It is suggested that in bovine milk there is only one major lipase and that it is identical to lipoprotein lipase.
TL;DR: A crude sectioning of the aorta revealed specific activity of lipoprotein lipase to be highest at the endothelial side of the artery, and added low concentrations of heparin or Ca2+ to the enzyme caused a slight stimulation of the lipolytic activity.
Abstract: SummaryA lipoprotein lipase in the bovine arterial wall has been identified and partially characterized. The enzyme has a Km apparent of 1 mM for triolein in a phosphatidylcholine stabilized emulsion. The lipase was stimulated 20- to 30-fold by the addition of heated rat plasma to the assay medium. The activity exhibited a pH optimum at 8.6. Protamine sulfate (1.0 mg/ml) inhibited the activity by 50%, whereas 1.4 M sodium chloride inhibited by 85%. Sodium fluoride, an inhibitor of the hormone-sensitive lipase, had no effect on the activity. Additions of low concentrations of heparin or Ca2+ to the enzyme caused a slight stimulation of the lipolytic activity. A crude sectioning of the aorta revealed specific activity of lipoprotein lipase to be highest at the endothelial side of the artery.
TL;DR: A patient with an unusual acute, generalized panniculitis had a five-fold elevation of urinary amylase level and a slightly elevated serum lipase leval without any signs or symptoms of pancreatic disease.
Abstract: A patient had an unusual acute, generalized panniculitis. The patient had a fivefold elevation of urinary amylase level and a slightly elevated serum lipase level without any signs or symptoms of pancreatic disease. A secretin test caused an eightfold elevation in urinary amylase level and some elevation of serum lipase and amylase levels, whereas study of duodenal drainage revealed no abnormalities. Skin specimens from the lesions showed considerable amylase and lipase activity, whereas specimens from controls and from subsequent patients with panniculitis showed no such abnormalities. Autopsy showed a normal pancreas, both grossly and microscopically.
TL;DR: Sodium deoxycholate and divalent cations such as Mg2+ and Ca2+ were extremely effective in stimulating phosphatidylcholine-hydrolyzing activity of this enzyme.
TL;DR: Oleic, lineoleic, and linolenic acids are primarily responsible for the increased trypsin-inhibiting activity of cooked soybeans after fermentation, and their effect appears to be a nonspecific type of inhibition.
Abstract: The trypsin-inhibitory activity observed in cooked soybeans fermented by Rhizopus oligosporus (fungus used in tempeh fermentation) has been examined. The active compounds have now been isolated by ethanol extraction and thin-layer chromatography and have been identified as free fatty acids by infrared spectroscopy and gas-liquid chromatography. Oleic, lineoleic, and linolenic acids are primarily responsible for the increased trypsin-inhibiting activity of cooked soybeans after fermentation. The free fatty acids are liberated from oil in the soybeans by fungal lipase, and they differ from other reported soybean trypsin inhibitors that are protein in nature. Free fatty acids have been previously reported to inhibit various enzymes, such as glycolytic, glyconeogenic, lipogenic, and also proteolytic. Their effect appears to be a nonspecific type of inhibition. Further studies are required to determine their physiological relevance, if any.
TL;DR: Characteristics of the clearing-factor lipase response of isolated fat-cells differ in several respects from those observed earlier with intact adipose tissue from 24h-starved rats, due to changes in the relative amounts of two different molecular forms of the enzyme that occur during the isolation of theFat-cells.
Abstract: 1. When fat-cells are isolated from the epididymal adipose tissue of 24h-starved rats and incubated at 25 degrees C in the presence of dialysed serum, glucose, insulin, amino acids and heparin, the total clearing-factor lipase acitivity of the incubation system increases progressively over a period of several hours. 2. All of the increase in activity is accounted for by the appearance of enzyme in the appearance of enzyme in the incubation medium and the fat-cell activity does not change significantly. Cycloheximids, at a concentration that prevents protein synthesis, does not affect the appearance of enzyme in the incubation medium, but the fat-cell enzyme activity is decreased in its presence. 3. The magnitude of the increase in total clearing factor lipase activity is unaffected by the omission of heparin from the medium. However, less enzyme is extracted in tis absence and the fat-cell activity increases. Cycloheximide again only affects the rise in cell activity and does not alter the activity in the incubation medium. 4. When serum in the incubation medium is replaced by casein, the distribution of enzyme between the cells and the medium is changed, but the magnitudes of the increases in total enzyme activity are similar. 5. These characteristics of the clearing-factor lipase response of isolated fat-cells differ in several respects from those observed earlier with intact adipose tissue from 24h-starved rats (Robinson & Wing, 1971; Cryer et al., 1973). The differences could be due, in part, to changes in the relative amounts of two different molecular forms of the enzyme that occur during the isolation of the fat-cells.
TL;DR: The triglyceridelipase of pig myocardium thus resembles lipoprotein lipase purified from adipose tissue and from plasma, but is clearly different from pig hepatic triglyceride lipase.
Abstract: 1. Lipoprotein lipase was purified from pig myocardium by a two-step purification procedure involving (a) the formation of an enzyme-substrate complex and (b) affinity chromatography on Sepharose which contained covalently linked heparin. The purified enzyme gave in sodium dodecyl sulphate-polyacrylamide-gel electrophoresis one main band with an apparent molecular weight of 73 000. The enzyme, which was purified 70 000-fold, had a specific activity of 860 mumol of unesterified fatty acid liberated/h per mg of protein. 2. The purified enzyme hydrolysed [14C]triolein emulsions in the absence of added cofactors but its activity was increased fivefold by adding normal human serum. Of the low-density lipoprotein apoproteins only apolipoprotein CII could be substituted for serum in activating the enzyme. This lipase had maximum activity at 0.05-0.15 M-NaCl. Heparin increased the activity of the purified enzyme twofold at low concentrations, but high concentrations inhibited. The triglyceride lipase of pig myocardium thus resembles lipoprotein lipase purified from adipose tissue and from plasma, but is clearly different from pig hepatic triglyceride lipase.
TL;DR: Rat heart lipoprotein lipase was highly purified by affinity chromatography using heparin-Sepharose 4B and was highly unstable; however, its activity could be partially stabilized by glycerol or ethylene glycol.
TL;DR: This chapter discusses the determination of hormone-sensitive triglyceride lipase from rat adipose tissue, which is responsible for the degradation of stored triglycerides in response to fat-mobilizing hormones such as catecholamines, glucagon, and adrenocorticotropic hormone.
Abstract: Publisher Summary This chapter discusses the determination of hormone-sensitive triglyceride lipase from rat adipose tissue. Adipose tissue contains at least two distinct triglyceride lipases. Lipoprotein lipase (LPL) is responsible for the degradation of the triglyceride moiety of circulating lipoproteins and thus controls the uptake of triglyceride fatty acids from plasma into adipose tissue. Hormone-sensitive lipase (HSL) is responsible for the degradation of stored triglycerides in response to fat-mobilizing hormones such as catecholamines, glucagon, and adrenocorticotropic hormone (ACTH). In the course of assay, free [ 14 C]oleic acid produced by hydrolysis of [ 14 C]triolein (labeled equally in all three acyl groups) is extracted and adsorbed onto an anion exchange resin. The adsorbed fatty acid is then displaced by strong base and the radioactivity is determined in a liquid scintillation counter (Method 1). Alternatively, the incubation mixture at the end of the assay period is subjected to a liquid-liquid partition to separate [ 14 C]oleic acid from unhydrolyzed [ 14 C]triolein and an aliquot of the upper aqueous phase containing the free fatty acid (FFA) is taken for scintillation counting (Method 2).