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Investigations of the mechanism behind the rapid absorption of nano-amorphous abiraterone acetate. Eur J Pharm Sci 2019; 129:79-86. [DOI: 10.1016/j.ejps.2019.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 12/27/2018] [Accepted: 01/01/2019] [Indexed: 11/18/2022]
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Point V, Pavan Kumar KVP, Marc S, Delorme V, Parsiegla G, Amara S, Carrière F, Buono G, Fotiadu F, Canaan S, Leclaire J, Cavalier JF. Analysis of the discriminative inhibition of mammalian digestive lipases by 3-phenyl substituted 1,3,4-oxadiazol-2(3H)-ones. Eur J Med Chem 2012; 58:452-63. [PMID: 23153815 DOI: 10.1016/j.ejmech.2012.10.040] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/05/2012] [Accepted: 10/21/2012] [Indexed: 01/13/2023]
Abstract
We report here the reactivity and selectivity of three 5-Methoxy-N-3-Phenyl substituted-1,3,4-Oxadiazol-2(3H)-ones (MPOX, as well as meta and para-PhenoxyPhenyl derivatives, i.e.MmPPOX and MpPPOX) with respect to the inhibition of mammalian digestive lipases: dog gastric lipase (DGL), human (HPL) and porcine (PPL) pancreatic lipases, human (HPLRP2) and guinea pig (GPLRP2) pancreatic lipase-related proteins 2, human pancreatic carboxyl ester hydrolase (hCEH), and porcine pancreatic extracts (PPE). All three oxadiazolones displayed similar inhibitory activities on DGL, PLRP2s and hCEH than the FDA-approved anti-obesity drug Orlistat towards the same enzymes. These compounds appeared however to be discriminative of HPL (poorly inhibited) and PPL (fully inhibited). The inhibitory activities obtained experimentally in vitro were further rationalized using in silico molecular docking. In the case of DGL, we demonstrated that the phenoxy group plays a key role in specific molecular interactions within the lipase's active site. The absence of this group in the case of MPOX, as well as its connectivity to the neighbouring aromatic ring in the case of MmPPOX and MpPPOX, strongly impacts the inhibitory efficiency of these oxadiazolones and leads to a significant gain in selectivity towards the lipases tested. The powerful inhibition of PPL, DGL, PLRP2s, hCEH and to a lesser extend HPL, suggests that oxadiazolone derivatives could also provide useful leads for the development of novel and more discriminative inhibitors of digestive lipases. These inhibitors could be used for a better understanding of individual lipase function as well as for drug development aiming at the regulation of the whole gastrointestinal lipolysis process.
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Affiliation(s)
- Vanessa Point
- CNRS - Aix-Marseille Université - Enzymologie Interfaciale et Physiologie de Lipolyse - UMR 7282, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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Understanding the lipid-digestion processes in the GI tract before designing lipid-based drug-delivery systems. Ther Deliv 2012; 3:105-24. [PMID: 22833936 DOI: 10.4155/tde.11.138] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Many of the compounds present in lipid-based drug-delivery systems are esters, such as acylglycerols, phospholipids, polyethyleneglycol mono- and di-esters and polysorbate, which can be hydrolyzed by the various lipolytic enzymes present in the GI tract. Lipolysis of these compounds, along with dietary fats, affects the solubility, dispersion and bioavailibity of poorly water-soluble drugs. Pharmaceutical scientists have been taking a new interest in fat digestion in this context, and several studies presenting in vitro gastrointestinal lipolysis models have been published. In most models, it is generally assumed that pancreatic lipase is the main enzyme involved in the gastrointestinal lipolysis of lipid formulations. It was established, however, that gastric lipase, pancreatic carboxyl ester hydrolaze and pancreatic lipase-related protein 2 are the major players involved in the lipolysis of lipid excipients containing acylglycerols and polyethyleneglycol esters. These findings have shown that the lipolysis of lipid excipients may actually start in the stomach and involve several lipolytic enzymes. These findings should therefore be taken into account when testing in vitro the dispersion and bioavailability of poorly water-soluble drugs formulated with lipids. In this review, we present the latest data available about the lipolytic enzymes involved in gastrointestinal lipolysis and suggest tracks for designing physiologically relevant in vitro digestion models.
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Choi JH, Lee MY, Ramakrishna S, Kim Y, Shim JY, Han SM, Kim JY, Lee DH, Choi YK, Baek KH. LCP1 up-regulated by partial pancreatectomy supports cell proliferation and differentiation. MOLECULAR BIOSYSTEMS 2011; 7:3104. [DOI: 10.1039/c1mb05326d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Walters MP, Conway SP. Cholesterol esterase activities in commercial pancreatic enzyme preparations and implications for use in pancreatic insufficient cystic fibrosis. J Clin Pharm Ther 2001; 26:425-31. [PMID: 11722679 DOI: 10.1046/j.1365-2710.2001.00379.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Although clinical symptoms in pancreatic insufficiency are often dramatically improved by pancreatic preparations, these often fail to normalize biochemical indicators of malabsorption. It seemed relevant, therefore, to investigate the amounts of cholesterol esterase in these preparations and, using in-vitro methods, some of the activities of this enzyme. The enzyme is just as physiologically important as lipase in accomplishing lipid digestion and absorption. METHODS Cholesterol esterase was assayed in commercial pancreatic extract preparations, lyophilized pig pancreas and human duodenal fluid. The in-vitro activities of the enzyme were also investigated on single and mixed dietary substrates. RESULTS Other than Creon, the commercial preparations showed negligible cholesterol esterase activities, whereas considerable activities were found in pancreatic tissue and duodenal fluids. In-vitro, pig cholesterol esterase was confirmed to be dependent on 3-hydroxy bile salt concentration for hydrolysis and synthesis and that the rate for hydrolysis greatly exceeds that of synthesis in normal concentrations of bile salts. However, with mixed lipid substrates, no bile salt concentration was found at which hydrolysis or synthesis predominates. CONCLUSIONS When pancreatic or hepato-biliary function is compromised, optimum lipid hydrolysis may not be achieved in therapeutic use, and the pig enzyme may perform differently to the human enzyme. In-vivo trials may reveal whether augmentation of the commercial products with this enzyme would be worthwhile.
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Affiliation(s)
- M P Walters
- Department of Chemical Pathology, United Leeds Teaching Hospital, Britannia House, Britannia Road, Morley, Leeds LS27 0DG, UK.
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8
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Li F, Hui DY. Modified low density lipoprotein enhances the secretion of bile salt-stimulated cholesterol esterase by human monocyte-macrophages. species-specific difference in macrophage cholesteryl ester hydrolase. J Biol Chem 1997; 272:28666-71. [PMID: 9353334 DOI: 10.1074/jbc.272.45.28666] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Reverse transcriptase-polymerase chain reaction was used to study the biosynthesis of two different cholesteryl ester hydrolases by human and mouse macrophages. Oligonucleotide primers for bile salt-stimulated cholesterol esterase yielded positive reactions with RNA isolated from human peripheral blood monocytes, monocyte-derived macrophages, the human monocytic THP-1 cells, and phorbol ester-induced THP-1 macrophages. In contrast, oligonucleotide primers for hormone-sensitive lipase yielded positive reactions only with RNA isolated from non-differentiated human THP-1 monocytic cells and peripheral blood monocytes, but not those obtained from differentiated THP-1 macrophages or monocyte-derived macrophages. Thus, while human monocytes were capable of synthesizing both enzymes, human macrophages synthesized only bile salt-stimulated cholesterol esterase and not the hormone-sensitive lipase. The synthesis of bile salt-stimulated cholesterol esterase by human macrophages was confirmed by detection of bile salt-stimulated cholesteryl ester hydrolytic activity in conditioned media of differentiated THP-1 cells and human peripheral blood monocyte-derived macrophages. Moreover, incubating human macrophages with oxidized low density lipoprotein (LDL) or acetylated LDL increased bile salt-stimulated cholesterol esterase activity in the conditioned media of these cells. These results with human macrophages were contrasted with results of studies with mouse macrophages, which showed the presence of hormone-sensitive lipase mRNA but not the bile salt-stimulated cholesterol esterase mRNA. Taken together, these results demonstrated species-specific differences in expression of cholesteryl ester hydrolytic enzymes in macrophages. The expression of bile salt-stimulated cholesterol esterase by human macrophages, in a process inducible by modified LDL, suggests a role of this protein in atherogenesis.
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Affiliation(s)
- F Li
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0529, USA
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9
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Affiliation(s)
- S R Feaster
- Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC 20307, USA
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Vakos HT, Burton GW, Kaplan H. Taurocholate-induced dimerization of bovine cholesterol esterase in sodium dodecylsulfate. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1342:103-8. [PMID: 9366275 DOI: 10.1016/s0167-4838(97)00101-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Purified bovine cholesterol esterase (CE) showed one major band with an apparent molecular mass of 58 kDa on sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In the presence of taurocholate another major band with an apparent molecular mass of 116 kDa, corresponding to the dimer, appeared. Longer heating times and higher concentrations of CE in SDS-sample buffer increased the relative amount of the dimer. Higher SDS concentration in the sample buffer reduced the amount of dimer. Mercaptoethanol concentration had no effect. The dimer did not contain taurocholate and readily reverted to the monomer. It is concluded that taurocholate mediates the dimerization of CE in SDS by facilitating the formation of hydrophobic interactions between monomeric subunits.
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Affiliation(s)
- H T Vakos
- Department of Chemistry, University of Ottawa, Ontario, Canada
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11
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Tsujita T, Miyazaki T, Tabei R, Okuda H. Coenzyme A-independent monoacylglycerol acyltransferase from rat intestinal mucosa. J Biol Chem 1996; 271:2156-61. [PMID: 8567673 DOI: 10.1074/jbc.271.4.2156] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Rat intestinal mucosa contains high diacylglycerol-synthesizing activity (monoacylglycerol acyltransferase (MGAT) activity) due to monoacylglycerol and fatty acid, independently of coenzyme A and ATP. MGAT activity was purified from rat intestinal mucosa by successive chromatography separations on DEAE-cellulose, CM- Sephadex, and anti-IgG-Sepharose against rat pancreatic lipase. The enzyme was electrophoretically homogeneous, and its molecular weight was 49,000, which is identical with that of rat pancreatic lipase. Immunoblotting analysis with antibody against rat pancreatic lipase showed one immunoreactive protein with an estimated molecular weight of 49,000. The activity of the purified enzyme was completely inhibited by addition of the antibody. Using immunocytochemical techniques, it was found that immunoreactive protein against rat pancreatic lipase was uniformly distributed within the absorptive cells of the intestine but was absent from the microvillar membrane. The MGAT activity of intestinal mucosal homogenate was inhibited by about 65% by addition of antibody against rat pancreatic lipase. Trioleoylglycerol- and dioleoylglycerol-hydrolyzing activities of the purified enzyme and pancreatic lipase were inhibited by addition of intestinal mucosa extract. These results suggest that pancreatic lipase is present in intestinal absorptive cells and that it may contribute to resynthesis of diacylglycerol from monoacylglycerol and fatty acids in these cells.
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Affiliation(s)
- T Tsujita
- Department of Medical Biochemistry, School of Medicine, Ehime University, Ehime, Japan
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Withiam-Leitch M, Rubin RP, Koshlukova SE, Aletta JM. Identification and characterization of carboxyl ester hydrolase as a phospholipid hydrolyzing enzyme of zymogen granule membranes from rat exocrine pancreas. J Biol Chem 1995; 270:3780-7. [PMID: 7876119 DOI: 10.1074/jbc.270.8.3780] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Salt-washed (0.6 m NaCl) zymogen granule membranes (ZGM) of rat pancreatic acinar cells were utilized to identify and characterize membrane protein(s) responsible for phospholipase and lysophospholipase activities. Five major bands were identified in salt-washed ZGM by Coomassie Brilliant Blue. A 70-kDa protein with enzymatic activity was retained in significant quantities after several washes with 0.6 M NaCl but could be displaced from ZGM by 2 m NaCl or by 100 mg/ml heparin. By contrast, GP2, an integral membrane protein, was not displaced under these conditions. These findings suggest that the enzyme is a peripheral membrane protein of ZGM. Renaturation of ZGM proteins following electrophoresis revealed that the 70-kDa protein possessed phospholipase activity. Identification of the 70-kDa protein as a membrane-associated carboxyl ester hydrolase was based upon: (a) the use of a specific polyclonal antiserum, (b) N-terminal sequence, (c) two-dimensional gel analysis, (d) enzymatic characterization, and (e) co-localization to an area of a non-reducing gel containing significant phospholipase activity. Other ZGM proteins, namely GP2 and GP3, could not be demonstrated to possess phospholipase activity under the experimental conditions employed. Our finding that carboxyl ester hydrolase from ZGM exhibits PLA1 and lysophospholipase activities represents the first identification and characterization of a protein responsible for phospholipase activity in secretory granule membranes.
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Affiliation(s)
- M Withiam-Leitch
- Department of Pharmacology and Toxicology, State University of New York, School of Medicine and Biomedical Sciences, Buffalo 14214
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Gjellesvik DR, Lorens JB, Male R. Pancreatic carboxylester lipase from Atlantic salmon (Salmo salar). cDNA sequence and computer-assisted modelling of tertiary structure. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:603-12. [PMID: 8001575 DOI: 10.1111/j.1432-1033.1994.tb20086.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We report the isolation and characterization of a 1795-bp cDNA fragment encoding Atlantic salmon pancreatic carboxylester lipase from salmon pancreas mRNA. The nearly full-length cDNA contained a 540-amino-acid open-reading frame, encompassing the mature protein (by similarity to mammalian carboxylester lipase enzymes). The salmon carboxylester lipase primary structure shared 58% identity with mammalian carboxylester lipases, lacking the proline-rich C-terminal repeats found in human and rat carboxylester lipases. Congruent with other esterase B type enzymes, the salmon carboxylester lipase contained a canonical serine-esterase catalytic triad motif consisting of serine, histidine and aspartic acid. Computer-assisted modelling of the tertiary structure for salmon carboxylester lipase was conducted using acetylcholine esterase (Torpedo californica) as a template structure. The model, in conjunction with sequence comparisons and available enzymological data, has been used to locate putative bile-salt-binding and lipid-binding sites. The carboxylester lipase enzymes contain a unique, highly conserved insert region that may be associated with bile-salt binding. In the model structure, this region is located close to the active site, and contains a tyrosine residue with an adjacent carboxylester-lipase-conserved arginine. These traits have previously been predicted for the non-specific (regarding bile-salt hydroxylation) bile-salt-binding site in carboxylester lipase enzymes. At this site, a dihydroxy or trihydroxy bile-salt molecule may bind the tyrosine via hydrophobic interactions, the anionic bile-salt head group may bind the arginine, while hydrogen bonding between the bile-salt 12 alpha hydroxy group and an adjacent aspargine residue is possible. The model does not contain an active site 'lid' structure as found in other lipases. The carboxylester lipase structural homolog to the 'flap' of the lipases from Geotrichum candidum and Candida rugosa contains a carboxylester-lipase-conserved deletion that renders this region unable to cover the active site. Instead, the shortening of this loop leads to solvent exposure of the carboxylester lipase insert region, an additional indication of the functional importance of this region.
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Affiliation(s)
- D R Gjellesvik
- Laboratory for Marine Molecular Biology, University of Bergen, Norway
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Tsujita T, Okuda H. The synthesis of fatty acid ethyl ester by carboxylester lipase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 224:57-62. [PMID: 8076651 DOI: 10.1111/j.1432-1033.1994.tb19994.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Carboxylester lipase obtained from pig pancreas is associated with fatty acid ethyl ester synthase as judged by their elution in the same fraction from a heparin-Sepharose column, coprecipitations by antibody against purified carboxylester lipase and identical profiles of inhibition by diisopropyl fluorophosphate. Only one polypeptide of molecular mass 74-kDa in purified carboxylester lipase was labeled by immunostaining and affinity labeling with [3H]diisopropyl fluorosphate. Bovine serum albumin decreased the fatty-acid-ethyl-ester-synthesizing activity in a concentration-dependent manner. On incubation of purified carboxylester lipase with trioleylglycerol in an ethanol/water mixture, fatty acid ethyl ester was formed in the presence of a high concentration of bovine serum albumin. The acyltransfer activities from trioleylglycerol to ethanol (ethanolysis) were approximately 25-30 times higher than the acyltransfer activities to water (hydrolysis). When cholesterol was used as an acceptor, acyltransfer activity from trioleylglycerol to cholesterol (cholesterolysis) was also observed. We propose the following mechanism of fatty acid ethyl ester formation from triacyl glycerol. The enzyme attacks triacyl glycerol forming an acyl-enzyme intermediate, and during the deacylation process, alcohol binds to fatty acid as an acceptor. These results suggest that during lipid (triacyl glycerol) degradation, carboxylester lipase contributes to non-oxidative ethanol metabolism in the intestinal lumen.
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Affiliation(s)
- T Tsujita
- Department of Medical Biochemistry, School of Medicine, Ehime University, Japan
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15
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Wilson MD, Rudel LL. Review of cholesterol absorption with emphasis on dietary and biliary cholesterol. J Lipid Res 1994. [DOI: 10.1016/s0022-2275(20)40109-9] [Citation(s) in RCA: 181] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Bile salt-dependent lipase biosynthesis in rat pancreatic AR 4-2 J cells. Essential requirement of N-linked oligosaccharide for secretion and expression of a fully active enzyme. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74454-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Sugo T, Mas E, Abouakil N, Endo T, Escribano MJ, Kobata A, Lombardo D. The structure of N-linked oligosaccharides of human pancreatic bile-salt-dependent lipase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 216:799-805. [PMID: 8404898 DOI: 10.1111/j.1432-1033.1993.tb18200.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study describes the structure of the N-linked oligosaccharide chains of bile-salt-dependent lipase isolated from the pancreatic juice of a normal donor. After hydrazinolysis, neutral sugar chains were separated from acidic chains by paper electrophoresis and were fractionated using serial column chromatography with immobilized lectins and Bio-Gel P-4 filtration. Structural analysis was performed by means of sequential glycosidase digestion and revealed that the neutral sugar chains are mainly of the biantennary complex type. Fucose residues were identified for some trimannosyl core structures and were alpha(1-6) or alpha(1-2) linked to the innermost GlcNAc residue and a terminal Gal residue, respectively. Sialyl residues were also involved in the oligosaccharide structures. Most of these structures have no linear N-acetyllactosamine repeats. Evidence from several approaches suggests that the sugar chains of the human pancreatic bile-salt-dependent lipase possess a blood-group-related antigenic determinant.
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Affiliation(s)
- T Sugo
- Institute of Medical Science, University of Tokyo, Japan
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Wang CS, Hartsuck JA. Bile salt-activated lipase. A multiple function lipolytic enzyme. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1166:1-19. [PMID: 8431483 DOI: 10.1016/0005-2760(93)90277-g] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- C S Wang
- Protein Studies Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Richmond W. Analytical reviews in clinical biochemistry: the quantitative analysis of cholesterol. Ann Clin Biochem 1992; 29 ( Pt 6):577-97. [PMID: 1489157 DOI: 10.1177/000456329202900601] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- W Richmond
- Department of Chemical Pathology, St Mary's Hospital, London, UK
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Gjellesvik DR, Lombardo D, Walther BT. Pancreatic bile salt dependent lipase from cod (Gadus morhua): purification and properties. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1124:123-34. [PMID: 1543734 DOI: 10.1016/0005-2760(92)90088-d] [Citation(s) in RCA: 183] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The enzymatic basis for cod digestive lipolysis has been investigated. Lipase activity was found in aqueous extracts from pyloric caeca as well as in pancreatic tissue surrounding the caeca and the bile duct. A bile salt-dependent lipase (BSDL) was purified from either defatted powder of cod pyloric caeca or aqueous pancreatic extracts by combined affinity chromatography on cholate-Sepharose and gel filtration on Sephacryl S-200 HR. By SDS-PAGE analysis the molecular weight of purified cod BSDL was estimated to 60 kDa. The enzyme was totally dependent on bile salts for hydrolysis of insoluble fatty acid esters. Antiserum raised against purified cod BSDL reacted specifically with selected mammalian pancreatic BSDLs by Western blot analysis. Results presented in this paper strongly suggest that the bile salt-dependent lipase is the only pancreatic enzyme involved in lipid digestion in cod. The enzyme has been characterized and compared to human pancreatic BSDL with respect to substrate specificity, temperature- and pH-dependence and inhibitors. Both soluble and insoluble fatty acid esters were hydrolysed and the enzyme was 1,3-specific in hydrolysis of triolein. The enzyme was inhibited by di-isopropyl fluorophosphate and phenyl boronic acid, but not significantly by phenyl methyl sulfonyl fluoride. The cod BSDL is probably homologous to mammalian pancreatic BSDLs.
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Affiliation(s)
- D R Gjellesvik
- Department of Biochemistry, University of Bergen, Norway
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Muderhwa JM, Schmid PC, Brockman HL. Regulation of fatty acid 18O exchange catalyzed by pancreatic carboxylester lipase. 1. Mechanism and kinetic properties. Biochemistry 1992; 31:141-8. [PMID: 1731866 DOI: 10.1021/bi00116a021] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The exchange of 18O between H2O and long-chain free fatty acids is catalyzed by pancreatic carboxylester lipase (EC 1.1.1.13). For palmitic, oleic, and arachidonic acid in aqueous suspension and for 13,16-cis,cis-docosadienoic acid (DA) in monomolecular films, carboxyl oxygens were completely exchanged with water oxygens of the bulk aqueous phase. With enzyme at either substrate or catalytic concentrations in the argon-buffer interface, the exchange of DA oxygens obeyed a random sequential mechanism, i.e., 18O,18O-DA in equilibrium with 18O,16O-DA in equilibrium with 16O,16O-DA. This indicates that the dissociation of the enzyme-DA complex is much faster than the rate-limiting step in the overall exchange reaction. Kinetic analysis of 18O exchange showed a first-order dependence on surface enzyme and DA concentrations, i.e., the reaction was limited by the acylation rate. The values of kcat/Km, 0.118 cm2 pmol-1 s-1, for the exchange reaction was comparable to that for methyl oleate hydrolysis and 5-fold higher than that for cholesteryl oleate hydrolysis in monolayers [Bhat, S., & Brockman, H. L. (1982) Biochemistry 21, 1547]. Thus, fatty acids are good "substrates" for carboxylester lipase. With substrate levels of carboxylester lipase in the interfacial phase, the acylation rate constant kcat/Km was 200-fold lower than that obtained with catalytic levels of enzyme. This suggests a possible restriction of substrate diffusion in the protein-covered substrate monolayer.
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Affiliation(s)
- J M Muderhwa
- Hormel Institute, University of Minnesota, Austin 55912
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Negre-Salvayre A, Abouakil N, Lombardo D, Salvayre R. Hydrolysis of fluorescent pyrene-acyl esters by human pancreatic carboxylic ester hydrolase and bile salt-stimulated lipase. Lipids 1990; 25:428-34. [PMID: 2215086 DOI: 10.1007/bf02538084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Fluorescent esters containing pyrenedecanoic acid (P10) or pyrenebutanoic (P4) acid (P4cholesterol, P10cholesterol, P4- and P10-containing triacylglycerols) were synthesized and used as substrates for human pancreatic carboxylic ester hydrolase and bile salt-stimulated lipase from human milk. Both enzymes were purified by immunoaffinity chromatography. All fluorescent pyrene derivatives were hydrolyzed by pancreatic carboxylic ester hydrolase and bile salt-stimulated lipase, but at different rates. The hydrolytic rates of the "short" acyl esters (P4-containing esters) were higher than those of the "long" ones (P10-containing esters). Conditions were optimized for sensitivity of the assay using fluorescent cholesteryl esters. The pH optimum was 7.5-8.0. Sodium cholate exhibited a stronger activating effect than taurocholate or taurodeoxycholate (maximal activation was achieved with 5 mmol/L cholate and with a molar ratio cholesteryl ester/cholate around 1:10). Both pancreatic carboxylic ester hydrolase and bile salt-stimulated lipase from milk were strongly inhibited by the other amphiphiles tested, namely phosphatidylcholine and Triton X-100, and were inactivated by low concentrations (10 mumol/L) of the serine-reactive diethyl-paranitrophenyl phosphate (E600). Both enzymes were strongly inhibited by relatively low concentrations of plasma low density lipoproteins. These studies indicate that the fluorescent esters containing pyrene fatty acids can be used as substrates for assaying and investigating the properties of pancreatic carboxylic ester hydrolase as well as bile salt-stimulated lipase from milk.
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Chen Q, Sternby B, Nilsson A. Hydrolysis of triacylglycerol arachidonic and linoleic acid ester bonds by human pancreatic lipase and carboxyl ester lipase. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 1004:372-85. [PMID: 2503032 DOI: 10.1016/0005-2760(89)90086-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The hydrolysis of polyenoic fatty acid ester bonds with pure human colipase-dependent lipase, with carboxyl ester lipase (CEL) and with these enzymes in combination was studied, using [3H]arachidonic- and [14C]linoleic acid-labelled rat chylomicrons as a model substrate. During the hydrolysis with colipase-dependent lipase, the amount of 3H appearing in 1,2-X-diacylglycerol (DG) markedly exceeded that of 14C. When CEL was added in addition this [3H]DG was efficiently hydrolyzed. CEL alone hydrolyzed the triacylglycerol (TG) at a low rate. The hydrolysis pattern with human duodenal content was similar to that seen with colipase-dependent lipase and CEL in combination. Increasing the concentration of taurodeoxycholate (TDC) and taurocholate (TC) or of TDC alone stimulated the hydrolysis of [3H]- and [14C]TG, but increased the accumulation of labelled DG that could act as substrate for CEL. It is suggested that very-long-chain polyenoic fatty acids of DG formed during the action of the colipase-dependent lipase on TG containing these fatty acids may be a physiological substrate for CEL.
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Affiliation(s)
- Q Chen
- Department of Medicine, University of Lund, Sweden
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Stephens TW, Schroepfer GJ. Inhibitors of sterol synthesis. Oleate ester of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one as a substrate for pancreatic cholesterol esterase. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 963:395-400. [PMID: 3196743 DOI: 10.1016/0005-2760(88)90307-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
5 alpha-Cholest-8(14)-en-3 beta-yl-15-one oleate (15-ketosteryl oleate), the oleate ester of a compound with the capacity to lower serum cholesterol, was effectively hydrolyzed by partially purified porcine pancreatic cholesterol esterase with an apparent Km of 0.28 +/- 0.01 mM and a Vmax of 0.62 +/- 0.01 mumol/min per mg protein compared to an apparent Km of 0.19 +/- 0.02 mM and a Vmax of 0.37 +/- 0.02 mumol/min per mg protein for cholesteryl oleate. The 15-ketosteryl oleate was also hydrolyzed by highly purified rat pancreatic cholesterol esterase with an apparent Km of 0.20 +/- 0.01 mM and a Vmax of 86.7 +/- 3.0 mumol/min per mg protein compared to an apparent Km of 0.43 +/- 0.01 mM and a Vmax of 119.8 +/- 2.6 mumol/min per mg protein for cholesteryl oleate. 15-Ketosteryl oleate is, therefore, a good substrate for pancreatic cholesterol esterase from either source. The 15-ketosterol is a weak competitive inhibitor of partially purified porcine pancreatic cholesterol esterase when cholesteryl oleate is the substrate.
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Affiliation(s)
- T W Stephens
- Department of Biochemistry, Rice University, Houston, TX
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Seki K, Horie S, Watanabe T, Suga T. Influence of 5-tridecylpyrazole-3-carboxylic acid, a new hypolipidaemic agent, on cholesteryl ester formation in rabbit intestinal mucosa. J Pharm Pharmacol 1988; 40:473-7. [PMID: 2904986 DOI: 10.1111/j.2042-7158.1988.tb05280.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The comparative effects of 5-tridecylpyrazole-3-carboxylic acid (TDPC), beta-sitosterol and melinamide on the esterification of cholesterol (CH) have been investigated in rabbit intestinal microsomes and cytosol in-vitro. The three agents did not show an effect on cholesteryl ester formation by cholesterol esterase (CEase). TDPC and beta-sitosterol did not affect cholesteryl oleate formation from oleoyl CoA by microsomal acyl CoA:cholesterol acyltransferase (ACAT), whereas melinamide significantly inhibited cholesteryl oleate formation. TDPC significantly inhibited the incorporation of oleic acid into cholesteryl oleate, which is associated with acyl CoA synthetase (ACS) plus ACAT in mucosal microsomes, at a concentration of 20-100 microM. On the other hand, 5-tridecylpyrazole-3-carbinol (TDPC-OH) a congener of TDPC, and beta-sitosterol did not show any effect. From these results, it is demonstrated that carboxylic moiety of TDPC is necessary to inhibit ACS in-vitro. According to the kinetic analytical results, it is suggested that TDPC acts as a competitive inhibitor of ACS. These results suggest that the inhibitory effect of TDPC on cholesteryl ester formation may be mediated by an inhibition of ACS activity. It is apparent from the data presented that there are substantial differences between TDPC, beta-sitosterol and melinamide with respect to their action on cholesteryl ester formation in rabbit intestinal mucosa.
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Affiliation(s)
- K Seki
- Department of Development, Morishita Pharmaceutical Co. Ltd, Tokyo, Japan
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Lechêne de la Porte P, Abouakil N, Lafont H, Lombardo D. Subcellular localization of cholesterol ester hydrolase in the human intestine. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 920:237-46. [PMID: 3607078 DOI: 10.1016/0005-2760(87)90100-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Immunocytochemistry and subcellular fractionation were used to localize the cholesterol ester hydrolase in the human small intestine. A positive immunoreaction, when using antibodies directed against pancreatic cholesterol ester hydrolase, was mainly found in endocytotic vesicles. Moreover, a label by gold particles was observed in intercellular spaces where lymphatic tissue merges. No specific immunoreactivity was obtained with the mucosa when sera directed against human pancreatic chymotrypsinogen and human pancreatic lipase were used. Conventional subcellular fractionation was performed after extensive washing of enterocytes to rule out any possible contamination by pancreatic enzymes. In these conditions a bile salt-dependent cholesterol ester hydrolase activity was detected in the soluble fraction of cells. Data agree with the concept that the intestinal cholesterol ester hydrolase may have a pancreatic origin. The absorption, if any, of this enzyme by enterocytes seems specific since other pancreatic (pro)enzymes tested (lipase, chymotrypsinogen) are not detected in these cells.
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Rudd EA, Mizuno NK, Brockman HL. Isolation of two forms of carboxylester lipase (cholesterol esterase) from porcine pancreas. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 918:106-14. [PMID: 3828371 DOI: 10.1016/0005-2760(87)90184-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Carboxylester lipase (cholesterol esterase, EC 3.1.1.13) has been purified to homogeneity from porcine pancreas. The enzyme is isolated in two molecular mass forms, a monomer of 74 kDa and a dimer of 167 kDa. The dimer consists of two catalytically-active subunits which have molecular masses approximately 9 kDa greater than the monomers. The difference in size was not attributable to carbohydrate or lipid content. The catalytic properties of the two forms are comparable on a weight basis, the amino acid compositions are quite similar, and the N-terminal sequences are nearly identical for 24 residues. These similarities suggest a possible precursor-product relationship between the two carboxylester lipase forms.
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Affiliation(s)
- F J Leinweber
- Department of Drug Metabolism, Hoffmann-La Roche Inc., Nutley, New Jersey 07110
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Hosie L, Sutton LD, Quinn DM. p-Nitrophenyl and cholesteryl-N-alkyl carbamates as inhibitors of cholesterol esterase. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75920-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Klemets R, Lundberg B. Substrate specificity of lysosomal cholesteryl ester hydrolase isolated from rat liver. Lipids 1986; 21:481-5. [PMID: 3762320 DOI: 10.1007/bf02535632] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The effect of various physicochemical forms of substrate on the activity of acid cholesteryl ester hydrolase isolated from rat liver lysosomes was studied. The amount of sodium taurocholate was varied in the substrate mixture which contained constant amounts of egg phosphatidylcholine (PC) and cholesteryl oleate. The resulting substrate forms produced were PC vesicles, PC vesicles with incorporated sodium taurocholate, mixed micelles, and mixed micelles together with free bile salt micelles. Gradually increasing amounts of sodium taurocholate activated cholesteryl oleate hydrolysis until the molar sodium taurocholate/PC ratio of ca. 0.6; thereafter hydrolytic activity decreased rapidly. The presence of sodium taurocholate micelles clearly inhibits cholesteryl oleate hydrolysis. We therefore propose that the activation observed at low bile salt concentrations depends on bile salt interaction with the substrate vehicle, whereas the inhibition observed at high bile salt concentrations depends on sodium taurocholate interacting with the enzyme. When comparing different phospholipid components in the supersubstrate, the enzyme activity was highest in the presence of dioleoyl PC and decreased when present with dipalmitoyl PC and egg PC. Egg lysoPC completely inhibited the enzyme activity. A net negative charge on the surface of the vesicle substrate increased cholesteryl ester hydrolase activity while a net positive charge on the surface inhibited the enzyme activity. Only part of the product inhibition of cholesteryl oleate hydrolase caused by Na-oleate was reversible when tested with bovine serum albumin present in the incubation mixture.
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Ponz de Leon M, Carubbi F, Di Donato P, Carulli N. Cholesterol esterase activity of human intestinal mucosa. Dig Dis Sci 1985; 30:1053-64. [PMID: 4053916 DOI: 10.1007/bf01315603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
It has been suggested that cholesterol absorption in humans is dependent on bile acid pool composition and that expansion of the cholic acid pool size is followed by an increase of the absorption values. Similar observations were reported in rats, where the increase of cholesterol absorption, after trihydroxy bile acid feeding, seems to be due to the stimulatory effect of cholic acid on the intestinal cholesterol esterase. In the present study, therefore, we investigated some general properties of human intestinal cholesterol esterase, with particular emphasis to the effect of bile acids on this enzymatic activity. Twenty-nine segments of small intestine were taken during operations; the enzymatic activity was studied by using mucosal homogenate as a source of enzyme and oleic acid, cholesterol, and 14C-labeled cholesterol as substrates. The time-activity relationship was linear within the first two hours; optimal pH for esterification ranged between 5 and 6.2. There was little difference between the esterifying activity of the jejunal and ileal mucosa. Esterification of cholesterol was observed with all the investigated fatty acids but was maximal with oleic acid. Bile acids did not affect cholesterol esterase activity when present in the incubation mixture at 0.1 and 1.0 mM; the enzymatic activity, however, was significantly inhibited when bile acids were added at 20 mM. In conclusion, this study has shown that the human intestinal mucosa possesses a cholesterol esterase activity; at variance with the rat, however, the human enzyme does not seem to be stimulated by trihydroxy bile acids. Thus, the stimulatory effect of cholic acid on cholesterol absorption induced by the administration of this bile acid does not seem to be simply due to changes of cholesterol esterase activity of the small bowel mucosa.
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Albro PW, Hall RD, Corbett JT, Schroeder J. Activation of nonspecific lipase (EC 3.1.1.-) by bile salts. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 835:477-90. [PMID: 4016142 DOI: 10.1016/0005-2760(85)90117-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The enzyme nonspecific lipase (EC 3.1.1.-) from rat pancreas has been isolated and its amino acid composition determined. The amino acid composition confirms more indirect evidence that nonspecific lipase is not the same enzyme as cholesteryl ester hydrolase. Activation of the enzymatic activity by bile salts has been studied by equilibrium dialysis, gel filtration, light scattering, circular dichroism and fluorescence polarization. The binding of bile salt by the enzyme is saturable and is associated with a conformational change. Upon binding cholate, the protein experiences a decrease in beta-structure with no significant change in alpha-helix content, an increase in apparent Stokes radius, a decrease in light scattering properties, and a slight decrease in polarization of the intrinsic tryptophan fluorescence. Attachment of bile salt is associated with decreased reactivity of essential sulfhydryl groups, but no detectable change in reactivity of amino groups. A change to a more nearly spherical shape upon binding bile salt would be consistent with the experimental observations, but the exact sites of binding remain uncertain.
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Roberts IM. Hydrolysis of 4-methylumbelliferyl butyrate: A convenient and sensitive fluorescent assay for lipase activity. Lipids 1985. [DOI: 10.1007/bf02534195] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Chapter 14 Roles of bile acids in intestinal lipid digestion and absorption. STEROLS AND BILE ACIDS 1985. [DOI: 10.1016/s0167-7306(08)60690-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Malavolti NL, Pilosof D, Nieman TA. Determination of cholesterol with a microporous membrane chemiluminescence cell with cholesterol oxidase in solution. Anal Chim Acta 1985. [DOI: 10.1016/s0003-2670(00)81743-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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37
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Buckley JT, McLeod R, Frohlich J. Action of a microbial glycerophospholipid:cholesterol acyltransferase on plasma from normal and LCAT-deficient subjects. J Lipid Res 1984. [DOI: 10.1016/s0022-2275(20)37729-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Field FJ. Intestinal cholesterol esterase: intracellular enzyme or contamination of cytosol by pancreatic enzymes? J Lipid Res 1984. [DOI: 10.1016/s0022-2275(20)37813-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Clark SB, Tercyak AM. Reduced cholesterol transmucosal transport in rats with inhibited mucosal acyl CoA:cholesterol acyltransferase and normal pancreatic function. J Lipid Res 1984. [DOI: 10.1016/s0022-2275(20)37835-4] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Labow RS, Adams KA, Lynn KR. Porcine cholesterol esterase, a multiform enzyme. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 749:32-41. [PMID: 6639954 DOI: 10.1016/0167-4838(83)90147-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cholesterol esterase (sterol-ester acylhydrolase, EC 3.1.1.13) has been purified from porcine pancreas by two methods, one of which was previously reported by Momsen, W.E. and Brockman, H.L. (Biochim. Biophys. Acta. 486 (1977) 102-113). Multiple forms of the enzyme were demonstrated throughout the course of both purification procedures. These forms hydrolyzed both p-nitrophenyl acetate as well as cholesteryl oleate. Isoelectric focusing was used to select one form of cholesterol esterase having a pI of 4.3 for further study. Using high-pressure liquid chromatography on a TSK Spherogel column this apparently homogeneous preparation of cholesterol esterase was separated into two components having molecular weights equal to 90 000 (peak I) and 45 000 (peak II). The number of each amino acid residue in peak I was double that of the corresponding residue in peak II, suggesting a dimer-monomer relationship. The N-terminal analyses showed that the first five amino acid residues were the same in peak I and peak II. The enzyme is a glycoprotein containing glucosamine, glucose, galactose, mannose and rhamnose; it is inhibited by diisopropyl fluorophosphate.
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4 Glyceride Digestion. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/s1874-6047(08)60302-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Billheimer JT, Tavani DM, Ritter KS. Acyl coenzyme A: Cholesterol acyltransferase activity in fat body and intestinal microsomes of heliothis zea. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/0305-0491(83)90183-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Karmanskii IM, Pichugin AL, Yusupova GI, Sysoev YA. Isolation of cholesterol esterase from dog's pancreatic juice. Bull Exp Biol Med 1981. [DOI: 10.1007/bf00839369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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46
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Bhat S, Brockman H. Enzymatic synthesis/hydrolysis of cholesteryl oleate in surface films. Inhibition by lecithin and its reversal by bile salts. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69717-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Lombardo D, Guy O. Effect of alcohols on the hydrolysis catalyzed by human pancreatic carboxylic-ester hydrolase. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 657:425-37. [PMID: 7213755 DOI: 10.1016/0005-2744(81)90328-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transfer reactions catalyzed by human pancreatic carboxylic-ester hydrolase (EC 3.1.1.1) were studied in the presence of methanol and butanol as nucleophiles. The addition of alcohols produced an increase in the total rate of 4-nitrophenyl acetate and n-propylthiol acetate disappearance and a concomitant slow decrease of the hydrolysis rate. These results indicate a competitive partitioning of an acyl-enzyme intermediate between water and nucleophile. Moreover, a strong inhibition of the rates of hydrolysis of methyl butyrate and triacetin by nucleophiles is in agreement with a rate-limiting acylation step. The kinetic data and a trans-ester characterization argue in favor of the formation of an acyl-enzyme intermediate and a two-step reaction mechanism, acylation and deacylation both being rate-limiting. The experiments performed with 4-nitrophenyl acetate show the existence of a nucleophile binding site.
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Abstract
Two electrophoretically different forms of sterol ester hydrolase (EC 3.1.1.13) were obtained from the cytoplasmic extract of the mycelia of Fusarium oxysporum. The entities, estimated at 60,000 (I) and 15,000 (II) molecular weights, were obtained in Sephadex G100 column chromatography of the ammonium sulfate precipitate from the cytoplasmic extract. A third form III, 75,000 MW, was obtained from the culture filtrate. The activity of the enzyme was increased by Triton X-100 and was not inhibited by p-chloromercuribenzoate (PCMB), a sulfhydryl reagent. The enzymes I and II were inhibited differentially by NaCl. The optimal activities of forms I, II and III occurred at pH 4.8, pH 8.0 and pH 7.0, respectively. The apparent Km values of 7.7 X 10(-5), 8.3 X 10(-5) and 10.5 X 10(-5), respectively, indicate a similar order of affinity for cholesteryl oleate at pH 7.1. The rate of hydrolysis of cholesteryl esters were in the order: linoleate greater than oleate greater than valerate greater than butyrate greater than acetate. Cholesteryl benzoate and palmitate were not hydrolyzed. The properties of the microbial enzyme are discussed in relation.
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Optimization and validation of assays to estimate pancreatic esterase activity using well-characterized micellar solutions of cholesteryl oleate and tocopheryl acetate. J Lipid Res 1981. [DOI: 10.1016/s0022-2275(20)34754-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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