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At least 289 records · Page 16Linked to original sources
PubMed1993

Adrenalectomy of the obese Zucker rat: effects on the feeding response to enterostatin and specific mRNA levels.

The effects of adrenalectomy on the feeding response to enterostatin and the mRNA levels of its parent protein, pancreatic colipase, have been investigated in lean (fa/?) and genetically obese (fa/fa) rats. Adrenalectomy reduced body weight gain and food intake of obese rats. Enterostatin inhibited the intake of high-fat diet in obese rats but not in lean rats. Adrenalectomy reduced food intake of all rats and abolished the response to enterostatin in the obese group. Obese rats had low levels of colipase mRNA, but these were normalized after adrenalectomy. The ability to respond to exogenous enterostatin is possibly linked to low levels of production of the peptide. The effects of adrenalectomy on brown adipose tissue uncoupling protein (UCP) mRNA and beta 3-adrenergic receptor (beta 3-AR) mRNA were also investigated. Northern blot analysis showed low levels of both UCP mRNA and beta 3-AR mRNA in obese rats that were restored to or toward the normal levels of lean rats by adrenalectomy. Adrenalectomy had no significant effects on mRNA levels in lean rats.

Adipose Tissue, Brown↗
PubMed2000

The C-terminal domain of pancreatic lipase: functional and structural analogies with c2 domains.

The 3D structure of pancreatic lipase (PL) consists of two functional domains. The N-terminal domain belongs to the alpha/beta hydrolase fold and contains the active site, which involves a catalytic triad analogous to that present in serine proteases. The beta-sandwich C-terminal domain of PL plays an important part in the binding process between the lipase and colipase, the specific PL cofactor. Recent structure-function studies have suggested that the PL C-terminal domain may have an extra role apart from that of binding colipase. This domain contains an exposed hydrophobic loop (beta5') which was found to be located on the same side as the hydrophobic loops surrounding the active site, and it may be involved in the lipid binding process. Indirect evidence for this new function of the PL C-terminal domain has been provided by studies with monoclonal antibodies directed against the beta5' loop. The catalytic activity of the PL-antibody complexes on water insoluble substrates decreased drastically, whereas their esterase activity on a soluble substrate remained unchanged. During the last few years, a number of protein structures (15-lipoxygenase, alpha-toxin from Clostridium perfringens) have been determined that contain domains with close structural homologies with the beta-sandwich C-terminal domain of PL. Generally speaking, these domains show structural homologies with the C2 domains occurring in a wide range of proteins involved in signal transduction (e.g. phosphoinositide-specific phospholipase C, protein kinase C, cytosolic phospholipase A2), membrane traffic (e.g. synaptotagmin I, rabphilin) and membrane disruption (e.g. perforin). Here it is proposed to review the structure and function of the C2 domains, based on the recent 3D structures and improved sequence alignments.

Amino Acid Sequence↗
PubMed1989

Evidence for multiple lipase forms in the rabbit pancreas.

Evidence is presented of the existence of at least two forms of lipase (A and B) in homogenized rabbit pancreas. These forms are separated by means of gel filtration and anion-exchange chromatography. Both forms are colipase-dependent, but lipase A is activated to a significant extent by 140 mmol/l NaCl even in the absence of the protein cofactor. Lipase A exhibits greater affinity towards emulsified triolein than does lipase B, as evidenced by the respective apparent Km values. Lipase B appears to be more colipase-dependent and resembles more closely the 'pancreatitis' lipase of human plasma. Form B is to be preferred as internal standard in turbidimetric and nephelometric indirect lipase assays.

Animals↗
PubMed1988

[Comparison of fungal lipase and pancreatic lipase in exocrine pancreatic insufficiency in man. Study of their in vitro properties and intraduodenal bioavailability].

Assuming that acidic degradation of lipase was the major cause of failure for the correction of steatorrhea by pancreatic extracts, we compared the in vitro and in vivo activities of a fungal lipase (FL) (Rhizopus arrhizus) with classical porcine pancreatic extract (Eurobiol). The choice of FL was determined by its two optimum pH (3.5 and 7.4). Five factors known to modify lipase activity were tested: pH, biliary acids colipase, trypsin and albumin. Bioavailability was measured by using a double intubation method in 13 patients with severe pancreatic insufficiency. Each enzymatic preparation was given during a test meal in a randomized and cross-over fashion. Results of the in vitro study showed that FL differed from pancreatic lipase by the following properties: better resistance in acidic solution, inhibition by biliary salts, absence of effect of colipase and rapid degradation by trypsin. In vivo the percentage of lipase activity recovered was 14.2 +/- 10.6 p. 100 for FL and 56 +/- 50 p. 100 for the classical pancreatic preparation. Compared with placebo significant differences in the recovery rate of lipolytic activity were observed with the pancreatic preparation only and started at the 40th min after the end of the test meal. These results showed that lack of degradation in acidic milieu is not the only valuable criterion for the choice of an efficient lipase preparation. The role of other potential factors such as gastric emptying as well as proteolytic degradation of the enzyme should be considered as well.

Bile Acids and Salts↗
PubMed1980

[Effect of bile salt excess in the duodenal lumen on the enzymatic equipment of pancreatic tissue in the pig].

This study reports the effect of long-term (8 days) addition of bile salts in the duodenal lumen of the pig in which the bile enterohepatic cycle was fully maintained. Seventeen pigs were fitted with permanent fistulae in the bile duct and the duodenum. The bile collected in 9 pigs was returned to the intestine, while that of the other 8 pigs was returned after a 30 p. 100 excess in bile salts, supplied by lyophilized porcine bile, had been added. At the end of the 8-day experimental period, the enzymes were determined in the fresh total pancreatic glands of all the pigs. The results showed no significant differences in lipase, colipase, amylase, chymotrypsin or trypsin activities in either group of animals. The existence of an in vivo relationship between bile salts and colipase secretions is hypothesized.

Amylases↗
PubMed1984

[The pancreatic lipase/colipase system].

Pancreatic lipase (triacylglycerol-acylhydrolase EC 3.1.1.3) hydrolyzes triglycerides on the lipid-water-boundary surfaces of micelles. The adsorption of the pancreatic lipase to the triglyceride boundary surfaces is inhibited by bile acid salts. Whereas colipase can be bound to boundary surfaces covered by bile acids and to pancreatic lipase. Colipase eliminates the inhibitory effect of physiologic concentrations of bile acid salts on the activity of lipase. The lipolysis by pancreatic lipase is characterized by activation of products and a biphasic kinetics. Extrapancreatic lipases of tongue, pharynx, oesophagus and stomach evoke the lipolysis of the fats contained in food.

Animals↗
PubMed1982

Product activation of pancreatic lipase. Lipolytic enzymes as probes for lipid/water interfaces.

During the action of pancreatic lipase and colipase on racemic 1,2-didodecanoylglycerol monolayers in the absence of bile salts, biphasic kinetics was observed under conditions of high lipid packing. Similar kinetics has earlier been reported using phospholipid-emulsified triolein droplets (Borgström, B. (1980) Gastroenterology 78, 954-962). These kinetics are characterized by a lag time tau d, dependent on products accumulation at the substrate/water interface. This lag time is differentiated from the previously described enzyme concentration independent lag time tau i in systems of low lipid packing (Verger, R., Mieras, M. C. E., and de Haas, G. H. (1973) J. Biol. Chem. 248, 4023-4034). Both tau i and tau d reflect a rate-limiting step due to the slow enzyme penetration into the substrate interface. The variation of tau d under different conditions (change in pH and concentration of Ca2+, enzyme, bovine serum albumin, and lipolytic products) lead us to propose a model for the product activation during lipolysis. We will discuss the use of the pancreatic lipase-colipase system to probe the lipid packing of emulsified triglyceride particles and lipoproteins using tau d as a reference value.

Animals↗
PubMed1978

Purification of pancreatic lipase via its affinity for bile salts and apolar surfaces.

An improved method for the purification of pancreatic lipase in milligram amounts is described. Only one batch step and one chromatographic step are required to produce a lipase-colipase complex and a lipase largely free of colipase. Both species are lipid free; physical and kinetic data indicate that the predominant lipase species is lipase B.

Animals↗
PubMed1995

Hydrolysis of galactolipids by human pancreatic lipolytic enzymes and duodenal contents.

Monogalactosyldiacylglycerols (MGDG), digalactosyldiacylglycerols (DGDG) and sulfoquinovosyldiacylglycerols (SQDG) are major lipids in vegetable food. Their digestion and absorption are unknown. This study examines the hydrolysis of galactolipids in vitro with human duodenal contents, pancreatic juice, and purified human pancreatic lipases. Galactolipids were incubated with human duodenal contents, pancreatic juice, pure pancreatic carboxyl ester lipase (CEL), and colipase-dependent lipase with colipase (Lip-Col). Hydrolysis was estimated as release of free fatty acids and by the use of [3H]galactose or [3H]fatty acid-labeled DGDG. Pancreatic juice and duodenal contents hydrolyzed DGDG to fatty acids, digalactosylmonoacylglycerol (DGMG) and water-soluble galactose-containing compounds. The hydrolysis of DGDG was bile salt-dependent and had a pH optimum at 6.5-7.5. Human pancreatic juice released fatty acids from MGDG, DGDG, and SQDG. Purified CEL hydrolyzed all three substrates; the hydrolysis rate was MGDG > SQDG > DGDG. Pure Lip-Col had activity toward MGDG but had little activity against DGDG. Separation of pancreatic juice by Sephadex G100 gel filtration chromatography revealed two peaks with galactolipase activity that coincided with CEL (molecular mass 100 kD) and lipase (molecular mass 50 kD) peaks. In contrast to pure Lip-Col enzymes of the latter peak were as active against DGDG as against MGDG. Thus, DGDG is hydrolyzed both by CEL and by a pancreatic enzyme(s) with a molecular mass of 40-50 kD to fatty acids and lyso DGDG. MGDG, DGDG, and SQDG are all hydrolyzed by human pancreatic juice. Pure CEL hydrolyzed all three substrates.

Bile Acids and Salts↗
PubMed1996

In vitro effects of ethanol on human gastric and pancreatic lipolytic activities/enzymes.

BACKGROUND: Ethanol ingestion may disturb fat digestion and absorption by affecting gastric, intestinal, hepatic, and pancreatic functions. Involved mechanisms are not well understood. We examined in vitro ethanol effects on gastric and pancreatic lipolytic activity. METHODS: Human gastric juice, pure gastric lipase, pancreatic lipase, colipase, carboxyl ester lipase, phospholipase A2, and duodenal contents were a) preincubated at 37 degrees C with ethanol (0-30%) and then assayed under normal conditions (pH-stat titration), or b) assayed in the presence of various ethanol concentrations (0-30%). RESULTS: Ethanol reduced gastric and pancreatic lipolytic activities in a dose-dependent manner. The effect was more pronounced with alcohol present in the assay medium, with 5% ethanol reducing carboxyl ester lipase activity by 10%, gastric lipase activity by 20%, and pancreatic lipase activity by 46%. Colipase and phospholipase A2 activities were only slightly affected by ethanol. CONCLUSIONS: Observed effects of ethanol on gastric and pancreatic lipase may be important when fat digestion is already impaired due to gastric, intestinal hepatic, and/or pancreatic diseases.

Carboxylesterase↗
PubMed1998

Alkaline lipase from brain: is it the same enzyme as pancreatic lipase from pancreas?

A new alkaline lipase was detected in rat brain and its properties were compared with those of the well-characterized pancreatic lipase and pancreatic lipase-related protein 2. The activity of the alkaline lipase was determined using trioleoylglycerol emulsion at pH 8.0. Subcellular fractions were prepared from brain homogenates by differential centrifugation. Lipase activities of the cytosolic fraction (the supernatant obtained by differential centrifugation of 100,000g) were stimulated by addition of colipase and bile salts and inhibited by addition of an antibody against rat pancreatic lipase. The partially purified enzyme had an isoelectric point of pH 6.8, which was identical to that found for rat pancreatic lipase. The enzyme had interfacial activation and dependence on colipase in the presence of bile salts. The enzyme had no measurable phospholipase A activity. The band produced by the enzyme on SDS-polyacrylamide gel electrophoresis was identical to that of the rat pancreatic lipase when detected by immunoblotting analysis using an antibody against pancreatic lipase. These results show that pancreatic lipase such as alkaline lipase is in rat brain.

Animals↗
PubMed2001

Effects of gum arabic on lipase interfacial binding and activity.

We investigated the surface behavior of gum Arabic (GA) as well as its effects on the lipolytic activity of human pancreatic lipase (HPL) and Humicola lanuginosa lipase (HLL), using emulsions of triacylglycerols (TAG) with various chain lengths. The effects of GA on the interfacial binding of HPL were also investigated. In the presence of 4 mM sodium taurodeoxycholate (NaTDC), GA (3% w/v, final concentration) had no effect on the HPL activity measured in the presence of colipase, whatever the type of TAG used. However, in the absence of bile salts or at low bile salt concentrations, GA inhibited the HPL activity when trioctanoin (TC8) and purified soybean oil (PSO) were used as substrates. At 3% (w/v, final concentration), GA strongly desorbed pure HPL from the TC8 interface and the classical anchoring effect of colipase was clearly observed. Both crude and dialyzed GA solutions were found to be highly tensioactive at the air-water as well as the oil-water interface using the drop technique. In conclusion, GA, or a putative contaminant present in GA, was found to be surface active and to have similar effects to those of bile salts on the interfacial binding and activity of HPL.

Caprylates↗
PubMed1994

Horse pancreatic lipase. The crystal structure refined at 2.3 A resolution.

Pancreatic lipase (EC 3.1.1.3) plays a key role in dietary fat digestion by converting triacylglycerols into 2-monoacylglycerols and free fatty acids in the intestine. Although the crystallographic structures of the human pancreatic lipase and of a human lipase-porcine colipase complex have been solved, no refined structure of pancreatic lipase has yet been published. The crystal structure of the horse enzyme was solved by the molecular replacement method from the model of the human pancreatic lipase and subsequently refined to 2.3 A resolution. The final model contains two molecules of 449 amino acid residues each in the asymmetric unit, 705 well-defined water molecules and two calcium ions. The two molecules in the asymmetric unit of the orthorhombic crystals are related by a 2-fold non-crystallographic symmetry axis as in the case of the human lipase. However, the association between the two molecules in their respective crystal forms is different. The overall molecular structure of the horse lipase is very similar to that of the human enzyme. The horse lipase is made up of two well-defined domains. The N-terminal domain which bears the active centre has a typical alpha/beta hydrolase fold topology. The C-terminal domain which is devoted to colipase binding has a beta-sheet sandwich topology. Comparison of equivalent C alpha atom positions between the final model of the horse lipase and the human lipase structure shows only slight differences which are mainly located in the C-terminal domain. The horse enzyme possesses the common features of the known mammalian and microbial lipases, in particular the "flap" covering the catalytic triad. In addition to more precise information concerning these features, the elucidation of the horse lipase crystal structure allowed us to better understand the structural basis of the kinetic behaviour of pancreatic lipases towards a soluble substrate, p-nitrophenyl acetate, and the different sensitivity of these enzymes towards limited proteolysis.

Amino Acid Sequence↗
PubMed1981

Porcine pancreatic lipase. Completion of the primary structure.

The complete primary structure of a lipase (triacylglycerol hydrolase; EC 3.1.1.3) is presented for the first time. The porcine pancreatic enzyme which was investigated is composed of a single chain of 449 amino acids. Upon fragmentation by CNBr, five peptides were obtained. The sequence of four of them (CN I-CN IV) has already been published. The present report deals with the arrangement of the 142 amino acids of the C-terminal peptide CN V, thus completing the analysis of the whole molecule. Special problems resulting from incomplete cleavage of some peptide bonds in CN V and aggregation of large peptides were overcome using Sephadex filtration of succinylated derivatives in 50% acetic acid, automated sequence analysis of peptide mixtures and subdigestion of material which could not be directly resolved. No obvious homology was found when the sequence of porcine lipase was compared with other protein, including pancreatic phospholipase A2 and colipase from the same species. However, a few similarities which might be significant were detected between the environment and relative position of certain half cystines in lipase and colipase, as well as between two tyrosine-rich regions existing in both proteins.

Amino Acid Sequence↗
PubMed2005

Purification and characterization of a novel lipase from the digestive glands of a primitive animal: the scorpion.

Higher animal's lipases are well characterized, however, much less is known about lipases from primitive ones. We choose the scorpion, one of the most ancient invertebrates, as a model of a primitive animal. A lipolytic activity was located in the scorpion digestive glands, from which a scorpion digestive lipase (SDL) was purified. Pure SDL, a glycosylated protein, has a molecular mass of 50 kDa, it presents the interfacial activation phenomenon. It was found to be more active on short-chain triacylglycerols than on long-chain triacylglycerols. SDL is a serine enzyme and possesses one accessible sulfhydryl group which is not essential for the catalysis. Among the NH2-terminal 33 residues, a 17 amino acids sequence shows similarities with sequence of Drosophila melanogaster putative lipase. Interestingly, neither colipase, nor bile salts were detected in the scorpion hepatopancreas. This indicates that colipase evolved in vertebrates simultaneously with the appearance of an exocrine pancreas and a true liver which produces bile salts. Furthermore, polyclonal antibodies directed against SDL failed to recognise the classical digestive lipases. Altogether, these results suggest that SDL is a member of a new group of digestive lipases belonging to invertebrates.

Amino Acid Sequence↗
PubMed1994

Human milk bile salt-stimulated lipase: functional and molecular aspects.

In breast-fed infants, digestion of milk triglycerides, the major source of energy and long-chain polyunsaturated fatty acids, is catalyzed by a concerted action of gastric lipase, colipase-dependent pancreatic lipase, and bile salt-stimulated lipase (BSSL). The major part of BSSL is present in the milk and the lesser part originates in the infant's exocrine pancreas. Gastric lipase is important in initiating digestion of milk fat globule triglycerides in the stomach. BSSL shifts the final products of triglyceride digestion from monoglyceride and free fatty acid (the products of colipase-dependent pancreatic lipase) to glycerol and free fatty acid, which may promote efficient absorption. Moreover, BSSL is likely to promote efficient use of milk cholesteryl- and fat-soluble vitaminesters and long-chain polyunsaturated fatty acids (> C18). The cDNA sequence has shown that BSSL has a unique primary structure. The N-terminal half is highly conserved between species and shows striking homology to typical esterases, for example, acetylcholine esterase. In contrast, the C-terminal half, containing 16 proline-rich repeats of 11 amino acid residues, is unique to BSSL. Using several recombinant variants of BSSL, we have found that these unique repeats and the glycosylation are completely dispensable for activity. Thus all typical properties of BSSL reside in the N-terminal half of the molecule.

Animals↗
PubMed1982

Studies on salivary and pancreatic lipases of the pre-ruminant calf.

Salivary and pancreatic lipases of the pre-ruminant calf have been studied using ion-exchange chromatography and gel filtration. In addition, pancreatic lipase has been fractionated using concanavalin A-affinity chromatography. The effects of 5,5'-dithiobis(2-nitrobenzoic acid), organic solvents and trypsin on pancreatic lipase have also been investigated. The effects of taurodeoxycholate on the lipolytic activity of the 2 lipases has been compared. Salivary lipase behaved as a single enzyme on ion-exchange chromatography, and gel filtration gave a mol. wt value of 52,000 for the enzyme. Although pancreatic lipase appeared to be a single enzyme on gel filtration, with a mol. wt of almost 80,000, the lipase was shown by ion-exchange and affinity chromatography to consist of at least 2 enzymes of mol. wts 72,000 and 60,000, and did not require colipase for maximum activity in the presence of high concentrations of bile salts. Colipase-dependent lipase, mol. wt about 45,000, and probably amounting to not more than 10% of the total activity, was also present. This was the predominant form only after large losses in total lipolytic activity had occurred, as after treatment with a mixture of ether, ethanol and deoxycholate, or prolonged action of trypsin. When the concentration of taurodeoxycholate was increased from zero to 1 mM in a tributyrin substrate, the lipolytic activities of calf salivary and pancreatic lipases, and pig pancreatic lipase, increased. At a concentration of 4 mM-taurodeoxycholate, calf salivary lipase activity was higher, that of calf pancreatic lipase lower and pig pancreatic lipase activity markedly lower.

Animals↗
PubMed1993

A structural domain (the lid) found in pancreatic lipases is absent in the guinea pig (phospho)lipase.

Typically pancreatic lipases are characterized by the following properties: (1) they are activated by lipid/water interfaces (interfacial activation), (2) they are inhibited by bile salts but reactivated by colipase (a small activator protein), and (3) they do not hydrolyze significantly phospholipids. A cDNA clone encoding a guinea pig pancreatic (phospho)lipase (GPL) has been sequenced and expressed. The enzyme (recombinant as well as native) differs from other pancreatic lipases in that (1) it is not interfacially activated, (2) its activity is unaffected by the presence of bile salts and/or colipase using tributyrin as substrate, and (3) it exhibits equally phospholipase A1 and lipase activities. The amino acid sequence of GPL is highly homologous to that of other known pancreatic lipases, with the exception of a deletion in the so-called lid domain that regulates access to the active centers of other lipases. We propose that this deletion is directly responsible for the anomalous behavior of this enzyme. Thus GPL challenges the classical distinction between lipases, esterases, and phospholipases.

Amino Acid Sequence↗