Showing papers on "Lipase published in 1980"

The effect of diets containing field beans of high or low polyphenolic content on the activity of digestive enzymes in the intestines of rats.

Abstract: Saline extracts of the intestinal contents of 36 rats, which had been randomly allocated into six dietary groups, were assayed for trypsin, α-amylase and lipase. The activities of both trypsin and α-amylase were significantly reduced in rats consuming diets containing testa from Dylan, a coloured flowered variety of field bean, whilst those receiving diets containing testa from the tannin-free, white flowered variety Triple White had comparable activities with those on a control testa-free diet. Polyvinyl-pyrrolidone-saline extracts of the gut contents, however, had similar trypsin activity for all diets and it was concluded that the original observed reduction in digestive enzyme activity was due to the presence of field bean polyphenolics, which are known to be present in the testa of all coloured flowered varieties. In contrast, lipase activity was increased in rats which received Dylan testa diets. It is suggested that the presence of field bean tannins stimulates an increased pancreatic secretion of all digestive enzymes; but in the gut, the affinity of tannin for lipase is less than for either dietary protein or the other digestive enzymes.

Lipoprotein lipase. Mechanism of product inhibition.

Abstract: The rate at which lipoprotein lipase hydrolyzes triglycerides in lipoproteins and in synthetic emulsions decreases sharply with the amount of products formed unless albumin is present. Three factors which contribute to this inhibition as follows. (a) The fatty acids and the monoglycerides formed on hydrolysis locate at the lipid-water interface of the emulsion and, since they are substrates for the enzyme, act as competitive inhibitors of triglyceride hydrolysis. (b) The enzyme forms complexes with fatty acids. Therefore, as fatty acids accumulate in the system some of the enzyme will be sequestered into enzyme-fatty acid complexes. Albumin can prevent formation of such complexes since it has a higher affinity for fatty acids than the enzyme has. (c) Activator proteins do not enhance triglyceride hydrolysis unless a fatty acid acceptor is present. The strong inhibition of the enzyme itself and the loss of lipolysis-stimulating effects of activator proteins provide a feed-back regulation of the action of the lipase on lipoproteins at the capillary endothelium, ensuring that products are not generated more rapidly than they are utilized by the tissue.

Lipoprotein Lipase: Some Effects of Activator Proteins

Abstract: This paper considers how apolipoprotein CII from human plasma lipoproteins and T1 and T2 proteins from egg yolk lipoproteins stimulate the activity of lipoprotein lipase. These activator proteins stabilized the enzyme much more effectively than a thousandfold higher concentration of albumin did, indicating a direct interaction with the enzyme. The effects of the activators were seen also at 1 M NaCl. Thus, forces other than electrostatic are implicated. Centrifugation experiments showed that 125I-labeled lipase bound equally well to the emulsion droplets in the absence of activator protein as in its presence. This was true even under conditions when the activator caused a severalfold increase in the rate of hydrolysis. Thus, the activator makes enzyme at the interface more effective in hydrolysis. By optimizing the conditions it was possible to obtain almost as high rates of triglyceride hydrolysis in the absence as in the presence of activator. Thus, the main effect of the activator protein is probably not on a rate-limiting chemical step. Under most conditions, the rate of hydrolysis was much below optimal and activator increased it. This was always the case with phosphatidyl-choline/triglyceride emulsions, where the activator enhanced hydrolysis of both lipids. Other experiments showed that the activator enhanced triglyceride hydrolysis in the absence of phospholipids and phospholipid hydrolysis in the absence of triglycerides. It is suggested that interaction with activator orientates the enzyme and/or the lipid substrate for effective hydrolysis at the surface of lipoproteins/model substrates.

Degradation of Acyl Lipids: Hydrolytic and Oxidative Enzymes

Abstract: Publisher Summary The term lipase is used to describe any enzyme activity causing the hydrolysis of lipids and long-chain acyl esters. A lipid biochemist is well aware of the high activities of lipolytic enzymes in many plants. The extraction and analysis of lipids, or of lipid-dependent membrane and enzyme preparations, are frequently severely affected by the presence of endogenous lipolytic activity. Methods for lipid extractions with plant materials have been developed to take account of potential degradation—normally by inactivating the relevant enzymes before extracting the lipids. Unwitting use of methods developed in mammalian biochemistry gives rise to artifacts and errors, and the problem is confounded by the fact that some lipolytic enzymes are activated by the organic solvents used in lipid extractions. Lipolytic enzymes are considered hydrolases using water as a co-substrate. However, most hydrolases act also as transferases when the cosubstrate is ROH.

Changes in Small Intestinal Digestive Enzyme Activity and Bile Acids with Dietary Cellulose in Rats

Abstract: BARBARA O. SCHNEEMAN ANDDANIEL GALLAHERDepartment of Nutrition, University of California,Davis, CA 95616ABSTRACT Rats were fed semipurified diets which contained either20% cellulose, Solka Floe, (HF) or no fiber (C) for 10 days. In the intestinal contents, the HF group had lower activity per milligram contents oftrypsin, chymotrypsin, amylase, lipase and total proteolytic activity. Totalactivity of enzymes in the intestinal contents was also lower, except forchymotrypsin and leucine amino peptidase. Bile acid levels per milligramwere lower in the HF group but the total amount was greater. The totalweight of intestinal contents was greater in the HF group and total amountof protein present was elevated. The results indicate that a source of dietaryfiber, cellulose, can affect the availability of enzymes and bile acids in thesmall intestine. J. Nutr. 110: 584-590, 1980.INDEXING KEY WORDSenzymes •bile acidsdietary fiber •digestion •pancreaticDietary fiber has been reported to increase the fecal excretion of fat and protein (1-4 ). Consumption of fiber may alsoalter the digestion and absorption of lipidand carbohydrate in the small intestine(1, 5). In vitro studies have shown thatcertain dietary fiber sources can lower theactivity of pancreatic lipase, trypsin andchymotrypsin (6). The present study wasundertaken to determine whether feedinga purified source of fiber, cellulose, couldaffect the intestinal activity of certain digestive enzymes and the level of bile acidsand cause adaptive changes in the enzymecomposition of the pancreas.

Gastric emptying and lingual lipase activity in cystic fibrosis.

Abstract: Summary: To identify gastric factors likely to contribute to fat maldigestion and malabsorption in cystic fibrosis (CF), gastric emptying time, secretion rate, and preduodenal lipolytic activity were studied. Gastric emptying of a liquid test meal and gastric acid secretion were determined in five CF teenagers with pancreatic insufficiency and in five healthy controls. During the first hr, the rate of gastric emptying exhibited a linear pattern in both CF patients and controls. Neither the emptying time nor the gastric secretion rate was different. Lingual lipase activity was measured in eight other CF patients with pancreatic insufficiency and in eight controls. Lipase activity was higher (P ≤0.05) in CF patients than in controls with values (± ± S.E.) of 34.48 ± 11.59 and 12.65 ± 5.60 μmole butyric acid min-1 ml-1, respectively. No correlation with age or body surface was observed. Intragastric lipolysis of a butterfat triglyceride test meal was fast in both groups, but more extensive (P ≤0.05) in CF patients than in controls. The data show that in CF with pancreatic insufficiency, gastric factors contributing to the first step of fat digestion are preserved. In fact, lingual lipase activity was found to be increased, and a more complete intragastric lipolysis was documented. Speculation: In view of the normal gastric emptying time, high lingual lipase activity, and significant degree of hydrolysis of a fatty meal taking place in the stomach of CF patients, the use of acid-resistant lingual lipase supplements could be considered as a new approach to the treatment of the lipolytic phase defect associated with pancreatic insufficiency in cystic fibrosis.

Heterogeneity of primary lipoprotein lipase deficiency.

Abstract: Lipoprotein lipase activity appeared in plasma within 10 min of beginning a heparin infusion in control subjects in whom adipose tissue lipoprotein lipase activity was normal. Plasma lipoprotein lipase activity was maintained throughout a heparin infusion lasting 4–6 hr. Three subjects with primary diminished adipose tissue lipoprotein lipase activity had markedly decreased lipoprotein lipase activity for the duration of the heparin infusion. However, the findings in two additional subjects suggest that the activity released during the early phase and during the late phase of the heparin infusion might come from different tissues. One subject had no adipose tissue lipoprotein lipase activity, but had levels of lipoprotein lipase in postheparin plasma similar to controls during the early phase of the heparin infusion. The other subject had normal adipose tissue lipoprotein lipase activity in the fasted and fed state, yet had little lipoprotein lipase activity in postheparin plasma during the early phase of the heparin infusion. This patient developed levels similar to that seen in plasma in the control subjects at the end of the heparin infusion. These findings suggest that (1) the activity that appears soon after initiating the heparin infusion is released from tissues other than adipose tissue, while that appearing later is of adipose tissue origin and (2) subjects with primary abnormalities of lipoprotein lipase form a heterogenous group of individuals.

Microbial lipolysis at low temperatures.

Abstract: It was found that lipase production during the growth of Pseudomonas fluorescens was not a function of the total number of bacteria The optimal temperatures for bacterial growth and lipase production were determined as 20 and 8 degrees C, respectively The lipolytic activity was studied in emulsions of olive oil at temperatures ranging from +8 to -30 degrees C After an initially rapid lipolysis, the reactions retarded at different levels depending on storage temperature Transference to a higher temperature resulted in a resumed lipolysis Also, at low temperatures, lipolysis was studied as a function of water activity and was found to occur in dehydrated substrates

Digestion and absorption of milk triacylglycerols in 14-day-old suckling rats.

Abstract: The fatty acid compositions of the major classes of lipid recovered from the contents of the stomach and small intestine, as well as, the chylomicron fraction of the serum of 14-day-old rats have been compared to that of the milk triacylglycerols. The results indicate that at least two lipolytic activities are involved. As well as pancreatic lipase in the small intestine, a second lipase is present in the stomach and removes approximately half of the medium-chain acids (8:0, 10:0, 12:0) which together comprise between 30 and 50% of the total milk fatty acids. Tracer amounts of radioactively labeled fatty acids were then fed with carrier milk lipid and the kinetics of the appearance of the label in the blood determined. The very rapid appearance (less than 5 minutes) of 8:0 and 10:0 suggested that these acids are absorbed directly across the stomach wall and transported as the free acid. The longer times required for the other acids fed indicate that they are abosrbed from the small intestine. While both 16:0 and 18:1 were predominantly esterified into triacylglycerols and secreted in the chylomicrons, 12:0 was transported mainly as the free acid via the portal vein. Unlabeled 9:0, 11:0 and 13:0 were each absorbed and transported as the next higher homolog.

Effects of dietary pectin and fat on the small intestinal contents and exocrine pancreas of rats.

Abstract: The effects of dietary pectin and fat level on digestive enzyme activities in the pancreas and small intestine and on intestinal bile acid levels were investigated. In unfed rats, dietary pectin did not influence the pancreatic enzymes studied, but a higher level of corn oil in the diet lowered the amylase activity in the pancreas, increased pancreatic lipase activity and slightly lowered the chymotrypsin and trypsin activities. Diet did not change the dry weight of the pancreas. In the fed rats, dietary pectin increased the dry weight of the small gut wash plus the mucosal scraping. Dietary pectin increased the small intestinal lipase and chymotrypsin levels and at the low level of fat only, increased amylase and trypsin activities in the small intestine of fed rats. Intestinal lipase levels were higher and amylase levels lower in rats consuming the high level of corn oil. These results indicate that changes in dietary fat level led to changes in the amylase and lipase content of secreted pancreatic juice and that differences in absorption associated with diets containing pectin could be the result of increased material in the small intestine.

Mechanism of action of milk lipoprotein lipase at substrate interfaces: effects of apolipoproteins

Abstract: The mechanism of action of bovine milk lipoprotein lipase was studied by using a monomolecular film of 1,2-didecanoylglycerol. The apparent rate of hydrolysis of diglyceride increased with increasing surface pressures above 12 mN/m; the enzyme was inactive at pressures less than 12 mN/m. We have measured the effects of four plasma apolipoproteins (apoC-II, apoC-III, apo-I, and apoE), bovine serum albumin, porcine pancreatic colipase, heparin, and NaCl on the kinetics of lipid hydrolysis. At a surface pressure of 15 mN/m, all of the proteins, with the exception of colipase, gave increased enzyme activity compared to lipase alone; apoC-II gave maximal activation. At 25 mN/m, apoC-II at concentrations of less than 0.25 microgram/mL showed a specific activation, whereas the other proteins had no effect. Heparin activated at both high and low surface pressures; NaCl had little or no effect in this system. At a higher concentration of apoC-II (0.50 microgram/mL), the apoprotein inhibited the enzyme. The addition of apoC-III, apoA-I, or apoE (final concentration 0.25 microgram/mL), but not albumin or colipase, to apoC-II (0.25 microgram/mL) caused an increase in surface pressure of 5-6 mN/m and an apparent rate which was less than half that found for lipase alone, suggesting that all of the apoproteins inhibit the apoC-II specific activation.

Effects of glucose and insulin on the activation of lipoprotin lipase and on protein-synthesis in rat adipose tissue.

Abstract: Glucose, and certain sugars that can readily be converted to glucose 6-phosphate, bring about an activation of adipose-tissue lipoprotein lipase when epididymal fat-bodies from starved rats are incubated in the presence of cycloheximide. Other substrates do not support the activation. If the tissue is preincubated in the presence of cycloheximide for longer than 2h, the ability of added glucose to activate the enzyme is lost. On the other hand, the addition of glucose still brings about an increase in lipoprotein lipase activity after preincubation in the absence of cycloheximide for as long as 4h. The magnitude of the increase in enzyme activity brought about by the addition of glucose is increased when protein synthesis is stimulated during the preincubation period by insulin. The results are interpreted in terms of the existence in adipose tissue of a proenzyme pool of lipoprotein lipase that is normally maintained by protein synthesis and that is converted to complete enzyme of higher specific activity by a process that specifically requires glucose.

Factors affecting lipase production in Aspergillus wentii.

Abstract: Aspergillus wentii showed maximum growth and lipase production at 30°C in 3 days at pH 6.0, when cultivated on a shaker. The medium supplemented with glucose showed maximum production of lipase followed by mannitol, fructose, galactose, sucrose, lactose, and maltose. Amongst the nitrogen sources tested, lipase yield was maximum with peptone at the 2% level. Calcium and sodium citrates (0l.%) increased the yield of lipase. Synthetic and natural lipids when added to the growth medium reduced the growth and lipase production.

Lingual lipase: an important lipase in the digestion of dietary lipids in cystic fibrosis?

Abstract: A convenient lipase assay that discriminates between pancreatic and lingual lipase activities was developed to describe some properties of the triglyceride-hydrolyzing activities of lingual lipase (from von Ebners glands) and pancreatic lipase. Secretion of lingual lipase is stimulated by feeding. Gastric contents collected postyprandially from patients with cystic fibrosis (CF) contained lipase activity which is probably secreted from pharyngeal tissues. Also, duodenal contents from CF patients contained lipase activity with properties very close to those found in gastric contents from CF patients and controls. Apparently, the serous glands responsible for the secretion of lingual lipase is less affected than the exocrine pancrease in this disease. During fat balance experiments, CF patients utilized around 40% of the dietary lipids and more than 50% of milk lipids given as a test meal were hydrolyzed in the duodenum within 2 hr. In these patients with severe pancreatic insufficiency, we suggest that the lingual lipase is responsible for a considerable proportion of triglyceride hydrolysis. This hydrolysis starts in the stomach and continues in duodenum.

High milk lipase activity associated with breast milk jaundice.

Abstract: Summary: Human milk samples that inhibit bilirubin-UDP-glucuronyl transferase (UDPGT) activity in vitro have been associated with prolonged unconjugated hyperbilirubinemia in newborn infants. We measured the concentrations of nonesterified fatty acids (total and individual fatty acids), total fat and protein, and lipase activities (with and without bile salt stimulation) in milk samples from two groups of women. Women whose infants had prolonged unconjugated hyperbilirubinemia and whose milk inhibited the activity of UDPGT were in the first group (N = 9). Volunteers with healthy infants acted as controls. Inhibitory milk contained significantly more nonester?fied fatty acids (total, palmitic, and oleic) than did controls. Fat and protein concentrations and bile salt-stimulated lipase activities were similar in the two groups. Unstimulated lipase activity was higher in the inhibitory milks (11.9 ± 0.8 mM±min-1±ml-1) than in the controls (6.0 ± 0.2 mM±min-1±ml-1) (P ≤0.01). The specific activity (mM±min-1±mg protein-1) of unstimulated lipase was also significantly higher in the inhibitory milks (P ≤0.0001). The high nonesterified fatty acid levels in inhibitory milks is accounted for by the elevated unstimulated lipase activities. How these circumstances lead to jaundice in the infants remains to be shown. Speculation: The strong association between high unstimulated lipase activity in human milk and the syndrome of breast milk jaundice leads us to conclude that fat digestion and absorption may have an important efffect on the metabolism of bilirubin in newborn infants. Further studv of the influence of the digestive Drocess on the absorption aid further metabolism of dietaiy lipid ih neonates may help to illuminate the relationship between lipid metabolism and neonatal hyperbilirubinemia.

LIPASE RELEASE FROM LYSOSOMES OF RAINBOW TROUT (Salmo gairdneri) MUSCLE SUBJECTED TO LOW TEMPERATURES

Abstract: Lysosomal lipases of the dark lateral line muscle of rainbow trout (Salmo gairdneri) had pH optima of 4.2–4.5 and 7.8. The acid lipase was chosen for further study. Presence of Triton X-100 in the reaction mixture enhanced the activity of the acid lipase. Fasting the fish for 24 and 72 hr prior to sacrifice resulted in higher acid lipase activities. Lysosomal preparations contained 60% of the acid lipase of the dark lateral line muscle. Storage on ice and fast and intermediate rates of freezing did not cause the release of acid lipase from the lysosomes. However, slow freezing and fluctuation of temperatures (−12° to −3.5° for 96 hr) of the frozen fillets resulted m appreciable release of the acid lipase from lysosomes. During frozen storage most of the release of acid lipase from the lysosomal fraction occurred within the first month of storage. Lower storage temperatures decreased the rate of acid lipase release from the lysosomal fraction.

Lipase Induction in Mucor hiemalis.

Abstract: The influence on lipase induction in Mucor hiemalis of different types of triglycerides containing mainly oleic acid (olive oil), erucic acid (mustard oil), or saturated fatty acids of 8 to 16 carbons (coconut oil) was studied. The fungus was grown in shake flasks in a fermentation medium containing peptone, minerals, and glucose or one of the oils as the carbon source. Maximum lipase was produced when the initial pH of the fermentation medium was kept at 4.0. Addition of Ca to the medium did not increase lipase production. The optimum pH for activity of both the mycelial and extracellular lipases was found to be 7.0. The fungus produced a significant amount of lipase in the presence of glucose, but the lipase activity increased markedly when olive oil was added to the medium at the beginning of the fermentation. Addition of olive oil at a later stage did not induce as much enzyme. Studies with washed mycelia showed that a greater amount of lipase was released when olive oil was present than when glucose was present. Among the various types of triglycerides used as the carbon source, olive oil was found to be most effective in inducing the lipase. Olive oil and mustard oil fatty acids inhibited the lipase more than those of coconut oil. The lipase induced by a particular type of triglyceride did not seem to be specific for the same triglyceride, nor was it inhibited specifically by it. Irrespective of the triglyceride used in the fermentation medium, the lipase produced was most active against coconut oil triglyceride, and this specificity, as shown by lipase activities in an n-heptane system, was not found to be due to a better emulsification of this oil. The lipase of M. hiemalis can be considered to be both constitutive and inducible.

Erucic acid-induced alteration of cardiac triglyceride hydrolysis.

Abstract: Male Wistar rats were fed for 3 or 10 days with high erucic acid rapeseed oil (HEAR) or trierucate (TE). These diets produced increased myocardial triglyceride (TG) levels. Cardiac lipid accumulation was related to basal-and hormone- (glucagon, norepinephrine) stimulated lipolysis, determined as glycerol release, which proved to be enhanced in isolated, perfused hearts from HEAR- and TE-fed rats. Endogenous TG levels in isolated hearts from rats fed the stock and the sunflowerseed oil (SSO) diet were low and probably rate-limiting for tissue lipolytic activities. HEAR feeding of rats did not modify the rate of erucic acid (22∶1) oxidation in heart. Prolonged HEAR and TE feeding led to a decrease in the endogenous TG level, a process in which the increased rate of TG hydrolysis might play an important role. The enhanced breakdown of tissue TG in hearts from TE-and HEAR-fed rats was accompanied by an increased release of fatty acids into the coronary effluent. Erucic acid was a major constituent of the perfusate fatty acids. Evidence is presented that the site of the intracellular TG breakdown is associated with lysosomes, since a subcellular fraction enriched in acid lipase, N-acetyl-β-glucosaminidase and TG could be isolated from heart homogenates of TE-fed rats. Fatty acids seemed to be an important regulator of tissue lipase activity: palmitate inhibited glucagon-stimulated lipolysis, which suggests the tissue lipase is subject to product inhibition by fatty acids.

Reduction of amphotericin resistance in stationary phase cultures of Candida albicans by treatment with enzymes.

Abstract: SUMMARY: The resistance of Candida albicans to amphotericin B methyl ester increases rapidly as cultures enter the stationary phase of growth; organisms harvested after several days in the stationary phase may have a resistance two or three orders of magnitude greater than that of exponentially growing organisms. This resistance is decreased by incubation of the organisms with enzymes which attack components of the cell wall. Of the enzymes tested, (1 → 3)-β-d-glucanases are the most effective; incubation of 7 d batch cultures with exo-(1 → 3)-β-d-glucanase at a concentration of 10 μg enzyme protein (mg dry wt organisms)-1 for 24 h at 37 °C and pH 6·5 reduces the resistance of the organisms to a value approximating to that of exponentially growing organisms. Resistance is also decreased by treatment with chitinase, lipase, trypsin, α-mannosidase and (1 → 6)-β-d-glucanases but, on a specific activity basis, none of these enzymes is as effective as (1 → 3)-β-d-glucanase. The action of (1 → 3)-β-d-glucanase is markedly enhanced by the addition during incubation of chitinase, trypsin or lipase.

Purification and Properties of Partial Glyceride Hydrolase of Penicillium cyclopium M1

Abstract: A lipolytic enzyme which hydrolyzed monoacylglycerols more easily than triacylglycerols was found in the culture broth of Penicillium cyclopium M1. The enzyme was purified to homogeneity and its properties were investigated. Among various substrates used, monoacylglycerols, especially those of medium chain fatty acids, were hydrolyzed very rapidly. Although the rate was low, the enzyme hydrolyzed methyl esters of fatty acids, Span or triacylglycerols of medium chain fatty acids. Based on its substrate specificity, the enzyme was regarded as a partial glyceride hydrolase. When the partial glyceride hydrolase was used in conjunction with lipase on triacylglycerol, the degree of hydrolysis of triacylglycerol became extremely high.