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At least 127 records · Page 7Linked to original sources
PubMed1987

Secretion of pancreatic lipase and colipase from rat pancreas.

Rat pancreatic juice was collected from female, anesthetized Sprague-Dawley rats (200-250 g) during basal secretion and after 45-min intravenous infusion for secretin or secretin with cholecystokinin (CCK). The volume of secretion was measured as well as activity of lipase and colipase. It was shown that the basal secretion of pancreatic juice gave a colipase/lipase (C/L) ratio of about 0.5. Stimulation with secretin or addition of CCK to secretin gave a C/L ratio between 0.4 and 0.6. This was not significantly different from the ratio found in basal secretion. The secretion of lipase and colipase from isolated pancreatic acini was also found to parallel a C/L ratio equal to 0.6 in the basal release and to a ratio between 0.5 and 0.6 after stimulation with CCK, secretin, or carbachol. The total activity ratio of C/L in the pancreas was equal to 0.97. It is concluded that lipase and colipase are secreted in parallel both in vivo and in vitro. The reason for a lower ratio of C/L in the secreted juice compared to the C/L ratio of pancreatic gland is not known.

Animals↗
PubMed1981

Stabilization of the C-terminal part of pig and horse colipase by carboxypeptidase and trypsin inhibitors.

Pig and horse colipases have been purified by a common procedure using trypsin and carboxypeptidase inhibitors as stabilizers. Two forms of pig colipase were identified: a predominant A1 form with about 103-105 residues, and a minor slightly degraded A2 form in which the last two C-terminal residues, Asp and Ser, were lacking. This type of degradation is considerably slowed down by carboxypeptidase inhibitors. A total of four forms of the horse cofactor were characterized: two (A1 and B1) were probably isocolipases which differed by only a few substitutions. Both contained the same number of residues (about 96), an N-terminal valine and an Arg-Ser-Glu-(Glx)1,2-ArgC-terminal sequence. A2 and B2 were slightly degraded forms probably resulting from tryptic cleavage of the Arg-Ser bond in the above sequence. The presence of methionine in the horse cofactor allowed fragmentation by cyanogen bromide. The C-terminal fragment was composed of 16 or 17 residues and contained no histidine. The single histidine of horse B1 was found in the intermediary fragment between Met-18 and Met-(n-17). These data show that the C-terminal parts of both pig and horse colipases are still more exposed to proteolytic degradations than the N-terminal parts. Preliminary attempts to crystallize B1 were carried out.

Animals↗
PubMed1990

Isolated lipase and colipase deficiency in two brothers.

Two brothers of Arab origin, aged 15 and 10 years, with isolated congenital lipase and colipase deficiency are described. Both were normally developed with a history of passing greasy stools since early infancy. Both have remarkable steatorrhoea and low serum carotene and vitamin E concentrations. After exocrine pancreatic stimulation, lipase and colipase activities in the duodenal fluid were almost completely absent, while amylase trypsin, bile salt, and pH values were normal. No other aetiology for exocrine pancreatic insufficiency was found. This is the first report of congenital combined lipase and colipase deficiency in two brothers.

Adolescent↗
PubMed1982

Hydrolysis of milk fat globules by pancreatic lipase. Role of colipase, phospholipase A2, and bile salts.

Human milk fat globules require colipase to be hydrolyzed by pancreatic lipase in the presence of bile salts. This is contrary to a recent report in this Journal (J. Clin. Invest. 67: 1748-1752.) according to which inhibition of lipase by bile salt could be overcome by the addition of colipase or phospholipase A2. This latter finding is shown to be due to contamination of commercially available pancreatic phospholipase A2 by colipase.

Animals↗
PubMed1990

The complete digestion of human milk triacylglycerol in vitro requires gastric lipase, pancreatic colipase-dependent lipase, and bile salt-stimulated lipase.

Gastric lipase, pancreatic colipase-dependent lipase, and bile salt-stimulated lipase all have potential roles in digestion of human milk triacylglycerol. To reveal the function of each lipase, an in vitro study was carried out with purified lipases and cofactors, and with human milk as substrate. Conditions were chosen to resemble those of the physiologic environment in the gastrointestinal tract of breast-fed infants. Gastric lipase was unique in its ability to initiate hydrolysis of milk triacylglycerol. Activated bile salt-stimulated lipase could not on its own hydrolyze native milk fat globule triacylglycerol, whereas a limited hydrolysis by gastric lipase triggered hydrolysis by bile salt-stimulated lipase. Gastric lipase and colipase-dependent lipase, in combination, hydrolyzed about two thirds of total ester bonds, with monoacylglycerol and fatty acids being the end products. Addition of bile salt-stimulated lipase resulted in hydrolysis also of monoacylglycerol. When acting together with colipase-dependent lipase, bile salt-stimulated lipase contributed also to digestion of tri- and diacylglycerol. We conclude that digestion of human milk triacylglycerol depends on three lipases with unique, only partly overlapping, functions. Their concerted action results in complete digestion with free glycerol and fatty acids as final products.

Bile Acids and Salts↗
PubMed1984

Isolated congenital lipase-colipase deficiency.

A 5-yr-old child with isolated combined pancreatic lipase and colipase deficiency is described. The patient has a history of passing oily stools since birth. Pancreatic stimulation tests showed that both lipase and colipase activities were less than 2% of normal control values. Despite the total lack of both enzymes, the patient's fat absorption coefficient was 50%. Fat absorption coefficient increased to 82% with pancreatic enzyme supplementation. This is the first report of congenital combined lipase and colipase deficiency.

Child, Preschool↗
PubMed1975

Binding of bile salts to pancreatic colipase and lipase.

The binding of conjugated bile salts to pancreatic colipase and lipase has been studied by equilibrium dialysis and gel filtration. The results indicate that at physiological ionic strength and pH, conjugated bile salts bind as micelles to colipase: 12-15 moles/mole of colipase for the dihydroxy conjugates and 2-4 for the trihydroxy conjugates. No binding of bile salt takes place from monomeric solutions. Under the same experimental conditions, only 1-2 moles of conjugated dihydroxy bile salts bind to pancreatic lipase.

Animals↗
PubMed1995

Rat GP-3 is a pancreatic lipase with kinetic properties that differ from colipase-dependent pancreatic lipase.

The pancreas contains three homologous proteins, colipase-dependent pancreatic lipase (PL) and two recently described pancreatic lipase-related proteins, PLRP1 and PLRP2. Rat (r) PLRP2 was first identified as a zymogen granule membrane protein, GP-3. Subsequently, we showed that rPLRP2 could cleave fatty acids from triglycerides, but the kinetic properties of rPLRP2 have not been further investigated. To further characterize rPLRP2, we expressed the recombinant enzyme in a baculovirus system, purified the secreted protein, and measured its kinetic properties. rPLRP2 had a broad pH optimum and the curve was similar to that of rPL. At pH 7.5, rPLRP2 cleaved short, medium, and long chain triglycerides by a kinetic mechanism that did not include interfacial activation. The activity against these substrates was not affected by bile salts. In particular, rPLRP2 did not show the bile salt inhibition typical of PL. Although colipase increased rPLRP2 activity in the presence of bile salts, the increase was only 2- to 5-fold compared to the absolute requirement for colipase that rPL had under these conditions. Finally, rPLRP2 could hydrolyze phospholipids, a substrate poorly hydrolyzed by PL. Our characterization of rPLRP2 demonstrates clear differences among the kinetic properties of rPLRP2 and rPL, rPLRP2, and PLRP2 homologues isolated from guinea pig and coypu pancreas. These findings have important implications for the physiological function of rPLRP2.

Amino Acid Sequence↗
PubMed1998

A structural homologue of colipase in black mamba venom revealed by NMR floating disulphide bridge analysis.

The solution structure of mamba intestinal toxin 1 (MIT1), isolated from Dendroaspis polylepis polylepis venom, has been determined. This molecule is a cysteine-rich polypeptide exhibiting no recognised family membership. Resistance to MIT1 to classical specific endoproteases produced contradictory NMR and biochemical information concerning disulphide-bridge topology. We have used distance restraints allowing ambiguous partners between S atoms in combination with NMR-derived structural information, to correctly determine the disulphide-bridge topology. The resultant solution structure of MIT1, determined to a resolution of 0.5 A, reveals an unexpectedly similar global fold with respect to colipase, a protein involved in fatty acid digestion. Colipase exhibits an analogous resistance to endoprotease activity, indicating for the first time the possible topological origins of this biochemical property. The biochemical and structural homology permitted us to propose a mechanically related digestive function for MIT1 and provides novel information concerning snake venom protein evolution.

Animals↗
PubMed1985

A colorimetric assay of pancreatic lipase: rapid detection of lipase and colipase separated by gel filtration.

A rapid assay for pancreatic lipase (E.C., glycerol-ester hydrolase 3.1.1.3) is described. The assay is based on the color change of a pH indicator as butyric acid is released from the substrate tributyrin. A mixture made with tributyrin and the water soluble components of the assay is ideally suited for use as a rapid test as, for example, when assaying chromatography fractions. Quantitative data can be obtained by measuring the disappearance of absorbance at 557 nm versus a blank reaction. The assay has been used in the rapid preparation of colipase-free lipase and colipase.

Chromatography, Gel↗
PubMed1981

Isolation and partial structural characterization of chicken pancreatic colipase.

Colipase has been isolated from acidic extracts of chicken pancreatic tissue homogenized with Triton X-100. The cofactor fully activates bile salt inhibited mammalian lipases. The amino terminal sequence of the avian protein has been determined up to position 39 and compared to the homologous region of the mammalian colipases (pig, horse, man) previously studied. From this comparison, it appears that a high degree of homology exists between the proteins.

Amino Acid Sequence↗
PubMed1981

Amino acid sequence of horse colipase B.

The complete sequence of the 96 residues composing horse colipase B has been determined by automated analysis of the intact protein, of two CNBr peptides and two tryptic peptides arising, respectively, from the citraconylated chain and from the unreduced protein. The single histidine of the protein is located at position 29 as in horse colipase A. His86, present in the C-terminal region of the pig cofactor and supposed to play a role in the folding molecule, is not conserved in horse B. Large pieces of the pig and horse B chains were found to be identical or very similar, especially the N-terminal sequence and the central segment Ala49-Cys65 including the three tyrosines of the molecule. The four lysines and the ten half cystines are also conserved.

Amino Acid Sequence↗
PubMed1991

Antigen specificity of anticolipase monoclonal antibodies: characterization of colipase-Fab complexes using gel filtration high-performance liquid chromatography.

The epitope specificity of eight mouse monoclonal antiporcine procolipase antibodies (MAbs) was characterized on the basis of their competitive binding with antigen. Binary and ternary Fab-colipase complexes formed between antibody and porcine procolipase or its trypsin activated derivative were identified using gel filtration HPLC. The eight MAbs were divided in two groups that recognized overlapping epitopes located in distinct antigenic regions on procolipase. The gel filtration HPLC technique allowed to characterize two MAbs which did not react with solid-phase coupled antigen. Three MAbs formed Fab-antigen complexes with procolipase and not with activated colipase which suggests that epitopes recognized by these MAbs involve residues of the N-terminal pentapeptide of procolipase.

Animals↗
PubMed1982

The reaction of porcine colipase a with tetranitromethane. Generation of extrinsic cotton effects in the visible region.

Porcine pancreatic colipase was reacted with a large excess of tetranitromethane in a two-phase system. Modification of tyrosine to produce nitrotyrosine generates extrinsic Cotton effects near 410 nm in the visible region which are not affected by submicellar concentrations of taurodeoxycholate. On the other hand, supramicellar concentrations specifically altered the spectrum near 350 nm. The total reaction products included both inter- and intramolecular cross-links and the initial mixture can be separated into monomers and polymers (dimers). Despite the complicated reactions that have taken place, the monomer has maintained full activity in a tributyrin-taurodeoxycholate assay system and the evidence supports a more indirect role for tyrosine in colipase interface reactions.

Animals↗
PubMed1984

Immunoreactive pancreatic colipase, lipase and phospholipase A2 in human plasma and urine from healthy individuals.

A radioimmunoassay for each of the human pancreatic proteins (colipase, lipase and phospholipase A2) is described. Determinations of the mean concentration of each protein in plasma and urine from healthy individuals were carried out with the radioimmunoassays. The values obtained in plasma were 0.5 nM (5.3 micrograms/l), 0.6 nM (32 micrograms/l) and 0.3 nM (4.3 micrograms/l) for colipase, lipase and phospholipase A2, respectively. In urine, the corresponding values were found to be 0.2 nM (2.4 micrograms/l), 0.09 nM (4.4 micrograms/l) and less than 0.017 nM (0.2 micrograms/l). No physical interaction between any of the three proteins and the lipid particles of plasma was demonstrated by centrifugation experiments or gel filtration. Gel filtration of plasma depleted of fat by centrifugation showed the proteins only in their monomeric form. The corresponding porcine proteins displayed a binding to antibodies against the human proteins, but with a lower affinity than the homologous interactions. The binding was weak but could differentiate between the porcine proforms and activated ones, i.e., procolipase and colipase87.

Adolescent↗
PubMed1979

Proton N.M.R. study of the conformational dynamics of porcine pancreatic colipase. Titration of aromatic residues.

The low-field portion of the 360 MHz proton N.M.R. spectrum of native porcine pancreatic colipase has been studied as a function of pH over the pH range 2-12. Resonances associated with the 26 protons of the aromatic rings of the two histidines, two phenylalanines and three tyrosines have been identified and tentatively assigned to specific residues. Titrations of pH yielded apparent pKa's of 7.9, 6.9, 10.4, 10.3 and 11.3 for His I (His 30), His II (His 86), Tyr I (Tyr 56 or 57), Tyr II (Tyr 56 or 57) and Tyr III (Tyr 53) respectively (tentative assignments). The high pKa value of His 30 is attributed to the vicinity of Asp 31. The mobility of the aromatic ring of Tyr 53 is hindered and an upper bound of 500 s-1 on the rate of rotation can be estimated. The aromatic rings of the 2 other tyrosine residues and of the 2 phenylalanine residues can rotate freely on the N.M.R. time scale. The study of perturbations in titration profiles and chemical shift values reveals a specific interaction of His 86 with Tyr I and, to a lesser extent, Tyr II. The existence of this interaction indicates that the protein folding brings in close spatial vicinity two distant regions of the covalent structure to form a "hydrophobic-aromatic" site which might be involved in the binding of bile salt micelles to pancreatic colipase.

Amino Acid Sequence↗
PubMed1978

Inhibition of lipase adsorption at interfaces. Role of bile salt micelles and colipase.

The effects of bile salts and colipase on the adsorption of lipase at an interface were studied by hydrophobic affinity chromatography on phenyl- and octyl-Sepharose. In the absence of bile salts, lipase or colipase binds separately to the gel. This is unchanged in the presence of adsorbed bile salts, when one bile salt molecule is associated per hydrophobic ligand. The same data are obtained in the presence of monomeric bile salt solutions. In contrast, lipase adsorption is totally prevented in a micellar bile salt solution. These results favor the idea that the formation of a lipase-bile salt complex in solution is responsible for the lack of interfacial lipase adsorption.

Adsorption↗
PubMed1978

Possible roles of bile lipids and colipase in lipase adsorption.

The adsorption isotherms of bile salts, phospholipids, and cholesterol were determined with siliconized glass beads. It was observed that the molar fractions of cholesterol, phospholipid, and bile polypeptide fractions increased simultaneously and considerably on the surface of the beads in comparison to the corresponding fractions found in bile. The composition of the adsorbed film is approximately 1 cholesterol: 2 phospholipid: 3 bile salt molecules. The performed complex of lipase, colipase, and bile lipids behaves as an entity which determines lipase adsorption. The modification of the interface quality of a lipid substrate by a detergent is not perse the reason for the lack of lipase adsorption. A model is proposed according to which lipolysis under physiological conditions would occur in two steps requiring two cofactors. Colipase would be necessary for the formation of the lipase-bile lipoprotein complex, and bile lipids would be required to direct the adsorption of this lipolytic entity toward the emulsified substrate.

Adsorption↗