Showing papers on "Lipase published in 1979"

Diglyceride lipase: a pathway for arachidonate release from human platelets.

Abstract: We provide evidence that the mechanism for arachidonate release from stimulated human platelets involves two enzymes: a phosphatidylinositol-specific phospholipase C (EC 3.1.4.10) and a diglyceride lipase. After incubation of platelets with thrombin for 15 seconds, 1.2 nmol of 1-stearoyl-2-arachidonoyl diglyceride per 10(9) platelets, was isolated. Arachidonate was released from this substrate by the action of diglyceride lipase located in the particulate fraction of platelets. The enzyme has a pH optimum of 7.0, is stimulated by calcium ions and reduced glutathione, and liberates 31 nmol of fatty acid per min per mg of platelet particulate protein. The diglyceride lipase has sufficient activity to account for the 5-10 nmol of arachidonate released per 10(9) platelets upon thrombin stimulation. That only arachidonate is released upon thrombin stimulation may be explained by the fact that the diglyceride substrate in platelets contains only arachidonate in the 2 position. The lipase activity found in platelet membranes can also hydrolyze the 1-position fatty acid. Stearate is not released when intact platelets are stimulated with thrombin, and the fate of this fatty acid remains to be elucidated.

Gastric Inhibitory Polypeptide Enhanced Lipoprotein Lipase Activity in Cultured Preadipocytes

Abstract: Fat feeding stimulated the release of gastric inhibitory polypeptide (GIP) without concomitant insulin secretion. Since antilipolytic effects of GIP have been demonstrated and the uptake of triglyceride fatty acid by adipose tissue postprandially is a process reciprocally regulated with lipolysis, a stimulatory role of GIP on adipose tissue lipoprotein lipase activity may be present. After cultured preadipocytes were incubated for 2 h with GIP, the release of lipoprotein lipase activity into the culture medium and the total cellular activity present in acetone-ether powders of cells were measured. GIP stimulated significant increases in the lipoprotein lipase activity released into the culture medium and in cells. A dose response relationship was strongest for the effect of GIP on the enzyme activity in extracts of acetone-ether powders of the cells. The increased lipoprotein lipase activity produced by GIP could provide a mechanisms for clearance of chylomicron triglyceride after feeding in man.

Localization of the heparin-releasable lipase in situ in the rat liver

Abstract: Immunofluorescence and immuno-electron microscopy were used for the localization of the heparin-releasable lipase in situ in the rat liver. The lipase is located exclusively on the liver endothelial cells. No labelling could be detected on the parenchymal of Kupffer cells, or in the livers of heparin-pretreated animals. The physiological significance of the endothelial localization of the hepatic lipase is discussed.

Synthesis of copolyamide–esters and some aspects involved in their hydrolysis by lipase

Abstract: Copolyamide–esters (CPAEs) were synthesized by the amide–ester interchange reaction. The change of intrinsic viscosity during CPAE synthesis was negligible. Polyamide blocks were shortened with increasing reaction time and polyester content. The polymerization degree of nylon 12 blocks on CPAE was smaller than that of nylon 6 blocks. CPAEs were hydrolyzed by Rhizopus delemar lipase. The biodegradability decreased with the shortening of the polyamide blocks and with increasing polyamide content. It was concluded that the amount and distribution of the hydrogen bonds, based on the amide group, in the CPAE chains strongly influenced their biodegradation by this lipase.

The effects of streptozotocin diabetes on hepatic triglyceride lipase activity in the rat

Abstract: The function of the hepatic triglyceride lipase (H-TGL) is not yet clear. The purpose of the present study was to investigate the possible hormonal regulation of H-TGL. Postheparin plasma was obtained 3 min after the intravenous injection of 50 U/250 g body weight of heparin into male Wistar rats. The lipase activities were measured using substrate containing [ 14 C] triolein emulsified with gum arabic and were expressed in μmoles of free fatty acid released/ml/hour (mean ± SD). H-TGL was the lipase activity remaining after inhibition of lipoprotein lipase (LPL) by 1.0 M NaCl. Diabetic rats were prepared by intravenous injection of streptozotocin (STZ), 65 mg/kg body weight. The contributions of H-TGL and LPL to the total plasma triacylglycerol hydrolase (TGH) activity depend on the amount of heparin injected and the time of blood withdrawal after heparin injection. H-TGL was maximally released at higher heparin (50 U/250 g body weight) concentrations, compared to LPL which was maximally released at lower heparin (5 U/250 g body weight) concentrations. H-TGL was significantly higher at 3 min after the injection of 50 U of heparin/250 g body weight than at 20 min. Twenty-four-hour fasting produced a significant fall in H-TGL compared to H-TGL in fed rats. Total TGH was significantly lower in diabetic rats 3 days after STZ injection. In diabetic rats 3, 5, and 7 days after STZ injection, H-TGL were significantly lower than those in control rats. H-TGL and H-TGL/total TGH were 9.49 ± 0.99 and 0.551 ± 0.071, respectively, in rats 3 days after STZ injection, compared to H-TGL (13.46 ± 0.69) and H-TGL/total TGH (0.739 ± 0.052) in control nondiabetic rats. When diabetic rats were treated with insulin, total TGH (14.37 ± 3.01) and H-TGL (6.77 ± 4.12) rose to 25.16 ± 1.02 (total TGH) and 16.46 ± 1.13 (H-TGL), that were comparable to activities in control nondiabetic rats. Separation of H-TGL and LPL was performed using heparin-Sepharose affinity chromatography of postheparin plasma. The enzyme activity of peak I from STZ rats, which is eluted by 0.72 M NaCl-Veronal buffer, pH 7.4 and corresponds to H-TGL, was approximately half the activity from control rats. TGH released by heparin from isolated rat liver parenchymal cells was investigated. The enzyme activities released from isolated liver parenchymal cells prepared from STZ rats was approximately half that from control rats. The role of insulin in the regulation of LPL has been well documented. Our findings suggest that H-TGL also is under hormonal regulation by insulin in rats.

Porcine pancreatic lipase. Sequence of the first 234 amino acids of the peptide chain.

Abstract: The single polypeptide chain of about 460 amino acids of porcine pancreatic lipase (EC 3.1.1.3) has been fragmented into five peptides by cyanogen bromide cleavage [Rovery, M., Bianchetta, J. & Guidoni, A. (1973) Biochim. Biophys. Acta, 328, 391--395]. The sequence of the first three cyanogen bromide peptides (CNI, CNII, CNIII), including a total of 234 amino acids, was fully elucidated. Automatic or manual Edman degradation was performed on the different peptides. Fragmentations of the CN peptides were accomplished by digestions with trypsin (after citraconylation or 1,2-cyclohexanedione treatment), chymotrypsin and Staphylococcus aureus external protease. Hydrolysis of unreduced material by pepsin and thermolysin, performed in order to determine the S-S bridge positions, provided useful overlapping peptides. The glycan moiety of lipase is bound to Asn-166. The non-essential tyrosine specifically blocked by diisopropylphosphorofluoridate is Tyr-49 in a cluster of asparagine and glutamine residues. The existence of a highly hydrophobic sequence (206--217) at the C terminus of the CNII fragment is noteworthy.

Colipase enhances hydrolysis of dietary triglycerides in the absence of bile salts.

Abstract: This study explores how dietary lipids are digested when intraduodenal bile salts are low or absent. Long-chain triglycerides emulsified with phosphatidylcholine were found to be hydrolyzed very slowly by pancreatic lipase alone, as if the surface layer of phospholipids enveloping the triglycerides impeded the action of the enzyme. Colipase enhanced triglyceride hydrolysis severalfold, both when added before or after the lipase. Hydrolysis became even more rapid when the emulsion was first incubated with pancreatic phospholipase. Hydrolysis of long-chain triglycerides was also severely impeded when other proteins were added to the system, probably because they adsorbed to the oil-water interface of the emulsion droplets. It was previously known that bile salts can relieve such inhibition, presumably by desorbing the adsorbed proteins. Colipase was found to enhance hydrolysis severalfold in a dose-dependent manner even in the absence of bile salts, i.e., it could partially or completely relieve the inhibition depending upon the amount and the type of inhibitory protein added to the system. Prior exposure of a protein-coated triglyceride emulsion to another lipase also enhanced the rate at which pancreatic lipase could then hydrolyze the lipids. Most dietary triglycerides are probably presented for intestinal digestion in emulsions covered by proteins and/or phospholipids. These emulsions would be hydrolyzed slowly by pancreatic lipase alone. However, through the action of the lipase in stomach contents and of pancreatic phospholipase and through the lipolysis-promoting effects of collipase, these triglycerices can be rather efficiently hydrolyzed, even in the absence of bile salts.

An enteric-coated pancreatic enzyme preparation that works.

Abstract: A new enteric-coated pancreatic enzyme preparation (microspheres) was compared with traditional enzyme tablets in six subjects with severe exocrine pancreatic insufficiency. The microspheres were found to be as effective as traditional enzyme supplements. In most patients in balance studies, the lowest fecal fat values were obtained with microsphere therapy in spite of a smaller amount of lipase administered (6015 vs 10,800–43,200 lipase units per meal). In contrast to enteric-coated tablets, microspheres can be recommended in the treatment of pancreatic steatorrhea.

Method for producing cacao butter substitute

Abstract: There is provided a method for producing a cacao butter substitute by transesterification of fats and oils containing glycerides rich in the oleyl moiety at the 2-position with an alcohol ester of stearic acid and/or palmitic acid in the presence of a lipase having reaction specificity to the 1,3-position of triglycerides and not more than 018% by weight of water based on the total weight of the reaction mixture By this method, a cacao butter substitute, rich in 1,3-distearyl-2-oleyl compound and 1-palmityl-2-oleyl-3-stearyl compound is obtained, in a high reaction yield with few by-products

Heparin-Released Plasma Lipases in Chronic Renal Failure and after Renal Transplantation

Abstract: 1. Post-heparin plasma from normal subjects, patients with chronic renal failure and recipients of renal allografts were subjected to affinity chromatography on heparin—agarose (Sepharose 4B) columns to separate two fractions representing hepatic lipase and lipoprotein lipase respectively. 2. The optimum conditions for assay of each fraction were determined for both normal and uraemic plasma. 3. Normal males had activities of hepatic lipase which were higher, and activities of lipoprotein lipase which were lower, than normal females. There was no consistent relationship to age for either enzyme. 4. Thirty patients with chronic renal failure untreated by dialysis had significantly elevated serum triacylglycerol concentrations, and significantly lowered lipoprotein lipase activities when compared with control groups with similar ages for each sex. However, only in uraemic males was hepatic lipase activity significantly reduced. 5. In a study of female patients with chronic renal failure, there were no significant differences in activities of hepatic lipase or lipoprotein lipase or concentrations of serum triacylglycerols between eight patients receiving dialysis treatment and eight untreated by dialysis. 6. Although serum triacylglycerol concentrations were raised in the group of 15 renal transplant recipients, lipase activities were not diminished. The only significant change was elevation of hepatic lipase activity in female graft recipients. 7. No relationship was found between the enzyme activities and fasting serum triacylglycerol concentrations in any group. However, there was a weak inverse correlation between serum creatinine and hepatic lipase in female patients from both renal failure and transplant groups. 8. Similar results were obtained when the enzymes were assayed with, as substrate, a laboratory-prepared emulsion of 14 C-labelled triolein in water with soya-bean lecithin as emulsifier, or commercially prepared soya-bean oil in water, emulsified with egg-yolk lecithin and containing glycerol (Intralipid).

Exocrine pancreatic function after total gastrectomy.

Abstract: The secretion of bicarbonate, lipase, and chymotrypsin into the duodenum in response to exogenous stimulation with secretin, 1 CU/kg-h, plus caerulein, 100 ng/kg-h, was investigated in 12 patients, on an average, 20.7 months after total gastrectomy and in 14 control subjects. The secretion of bicarbonate and lipase was significantly lower in patients than in controls. The reduction in outputs compared with the control values was 47.9%, 38.7%, and 24.2% respectively for bicarbonate, lipase, and chymotrypsin. Eight of the 12 patients (67%) had steatorrhoea. No significant correlation was found between this parameter and lipase output. It is concluded that the exocrine pancreatic function is impaired in the majority of patients subjected to total gastrectomy. The impairment, which particularly affects bicarbonate and lipase, is generally mild to moderate.

The role of gastric lipolysis on fat absorption and bile acid metabolism in the rat.

Abstract: In vivo studies were carried out in young Sprague-Dawley rats to examine the role of gastric lipolysis on fat absorption and bile acid metabolism. When fed by gastric perfusion 5 times (corn oil, 4 g/day) their usual dietary intake of fat, rats deprived of lingual lipase by the creation of an esophageal fistula had a significant degree of fat and bile acid malabsorption as well as a shortened bile acid halflife when compared to animals with a gastrostomy. The % fat absorption, bile acid loss and bile acid pool were normal in 2 groups of esophageal fistula rats fed the same quantity of corn oil or twice (8 g/day) that amount as a fine emulsion. In view of a negligible gastric lipase activity in animals with an esophageal fistula and of decreased hydrolysis of a triglyceride test meal, these data suggest that gastric lipolysis is of physiological importance in situations where lipolytic mechanisms are stressed by a large fat intake. Its principal role is to potentiate intestinal lipolysis by facilitating the emulsification of dietary lipids through its formed products and, therefore, the contact of pancreatic lipase with its substrates.

Diet composition and insulin effect on amylase to lipase ratio in pancreas of diabetic rats

Abstract: In man and in rat, the diabetic state is associated with diseases of exocrine pancreatic function. In this work, streptozotocin diabetes was shown to lead to a 95% decrease in the amylase to lipase ra

Properties of salt-resistant lipase and lipoprotein lipase purified from human post-heparin plasma.

Abstract: Lipoprotein lipase and salt-resistant lipase were isolated from human post-heparin plasma. The proteins of human post-plasma lipoprotein lipase and salt-resistant lipase were identified and demonstrated to be immunologically different. Significant differences between the two enzymes in their relative amino acid composition were demonstrated, which indicates that the two enzymes are different proteins. When analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the enzymes seemed to have monomer molecular weights similar to that of lipoprotein lipase purified from bovine milk.

Method of producing improved glyceride by lipase

Abstract: A glyceride product is prepared by interesterifying a glyceride mixture in the presence of a lipase as a catalyst with a dihydric alcohol, a trihydric alcohol, or mixture thereof, said glyceride mixture being composed of at least two different glycerides or at least one glyceride and at least one fatty acid.

Adaptation of the lipase-colipase system to dietary lipid content in pig pancreatic tissue

Abstract: This report studies the evolution of some enzymatic activities, i. e. mainly of the lipase-colipase system, in pig pancreatic tissue in response to a change in dietary lipid content. Twenty pigs were divided into two lots of ten each. One lot was fed a diet containing 5 p. 100 of peanut oil and the other a diet containing 25 p. 100 of peanut oil. Lipase and colipase activities in the tissue increased when dietary lipids were augmented. However, colipase increased less (-!37.7 p. 100) than lipase (+ 82.6 p. 100). The choice of a technique for studying the evolution of colipase activity is discussed.

Role of Lipoprotein Lipase in Plasma Triglyceride Removal

Abstract: Intravenous injections of anti-lipoprotein lipase serunis quantitatively block the catabolism of very low density lipoprotein (VLDL) and portomicron triglyceride and specifically inhibit triglyceride transport into ovarian follicles. The immunological studies presented provide information on the site of action of lipoprotein lipase (LPL). In the anti-LPL serum-treated animals initial plasma triglyceride accumulation occurs at the time of antiserum injection. This instantaneous inhibition of triglyceride removal provides direct evidence that the functional LPL responsible for VLDL and portomicron triglyceride hydrolysis is located in sites within the plasma compartment readily accessible to immunoglobulins. In vitro immunological studies show that the adipose, heart, ovarian, and liver LPL share common immunological determinants. Biochemical studies on highly purified heart and adipose LPL suggest that these enzymes have identical protein moieties.

Low resolution crystal structure of lipase from Geotrichum candidum (ATCC34614).

Abstract: Lipase from Geotrichum candidum (ATCC34614) is a glycerol ester hydrolase which has a molecular weight of 55,000 with about 7% carbohydrate, displaying a high affinity for triolein. The enzyme was crystallized from more than 2% protein solution without using any salt or organic solvent. The crystals were cross-linked by soaking in 0.37% glutaraldehyde solution (0.1 M acetate buffer solution, pH 5.6). The structure was determined by X-ray diffraction using the isomorphous replacement technique. Two heavy-atom derivatives [K2PtCl4 and UO2(CH3COO)2] were obtained by the soaking method. The electron density map calculated at 5 A resolution clearly showed the molecular boundary. A balsa wood model was made on the basis of the 6 A electron density map. The molecular has an ellipsoidal shape with dimensions of 70 A X 50 A X 50 A. Several columns of density corresponding to alpha-helix and a few clefts were found in the molecule. The active site is presumably located in the vicinity of one of the Pt sites in the Pt-derivative crystal, judging from the inactivation of the enzyme by K2PtCl4.