Showing papers on "Lipase published in 1976"
TL;DR: The mean activity of post-heparin plasma lipo-protein lipase was significantly lower in subjects with hyperprebetalipoproteinaemia than in normal individuals, however, many hypertriglyceridaemic patients had lipoprotein lipase within the normal range and there was no correlation between serum triglyceride concentration and the activity ofPost- heparin lipases.
Abstract: 1. A selective immunochemical method was used to measure post-heparin plasma lipoprotein lipase and hepatic lipase activity in eighty-two normal subjects and in twenty patients with type IIb, IV or V hypertriglyceridaemia. In twenty-six normal subjects the activity of post-heparin plasma lipases was compared with the kinetic parameters of endogenous plasma triglyceride metabolism. 2. The activity of post-heparin lipoprotein lipase was significantly higher in normal females than in males, whereas the activity of hepatic lipase showed an opposite sex ratio. The activity of lipoprotein lipase decreased with age both in males and females, whereas no significant age variation was observed in the activity of hepatic lipase. 3. In normal subjects a highly significant negative correlation was present in both sexes between the activity of post-heparin plasma lipoprotein lipase and fasting serum triglyceride concentration, but not between the activity of post-heparin hepatic lipase and serum triglycerides. 4. The fractional removal rate of endogenous triglycerides was positively correlated to the activity of lipoprotein lipase but not to the activity of hepatic lipase. No relationship was found between the activities of post-heparin plasma lipases and the absolute turnover of serum triglycerides. 5. The mean activity of post-heparin plasma lipoprotein lipase was significantly lower in subjects with hyperprebetalipoproteinaemia than in normal individuals. However, many hypertriglyceridaemic patients had lipoprotein lipase within the normal range and there was no correlation between serum triglyceride concentration and the activity of post-heparin lipases. 6. All three patients with fasting chylomicronaemia had low post-heparin lipoprotein lipase activity. Several subjects with high post-heparin plasma hepatic lipase activity were present in the group with hyperprebetalipoproteinaemia, but the mean value of the hepatic lipase was not significantly different from normal.
225 citations
TL;DR: Data indicate that following insulin treatment, increased lipoprotein lipase activity in adipose tissue results from enhanced enzyme secretion by the fat cell and subsequent accumulation in the tissue, thus implicating the adipocyte secretory mechanism as a major site of regulation of lipop protein lipaseActivity in adiposes tissue.
159 citations
TL;DR: It is found that the enzyme catalyzed hydrolysis of long chain triglycerides by pancreatic lipase from one species is activated by the addition of colipase from other species.
154 citations
TL;DR: Hormone-sensitive lipase and lipoprotein lipase, functionally distinct enzymes, have been physically resolved and immunochemically distinguished and seem to be regulated, at least directly, by cAMP-dependent protein kinase.
132 citations
TL;DR: It is suggested that a part of the activation of lipase at interfaces may be due to a conformational change resulting from adsorption of dissolved p-nitrophenyl esters.
Abstract: Hydrolysis of dissolved p-nitrophenyl acetate by pancreatic lipase follows the classical acyl enzyme pathway already proposed for other esterases. Kinetic parameters of the hydrolysis have been determined. The turnover rate of the reaction is many orders of magnitude slower than that for the natural emulsified substrates. Nevertheless, several arguments are in favor of the specificity of this hydrolysis: (1) triacetin, which resembles the usual substrates for the enzyme, is also hydrolyzed very slowly in solution; (2) dissolved triacetin and tripropionin are competitive inhibitors for the p-nitrophenyl acetate hydrolysis; (3) the same chemical structural features which are required in the case of emulsified substrates are also necessary to promote hydrolysis of dissolved p-nitrophenyl esters. This suggests that the same active site (or part of the same active site) is responsible for hydrolysis of both p-nitrophenyy acetate and specific emulsified substrates. Since deacylation is the rate-limiting step in the catalysis of p-nitrophenyl acetate, the intermediate acetyl enzyme can be isolated by trapping it at pH 5.0. Kinetic competence of this intermediate has been demonstrated. Hydrolysis by pancreatic lipase of dissolved monomeric p-nitrophenyl acetate and triacetin is considerably enhanced (100- to 500-fold) by various interfaces. This suggests that at least the deacylation step, which is rate limiting in absence of interface, is accelerated by the presence of inert interfaces. Siliconized glass beads were directly shown to accelerate the deacylation of isolated [3H]acetyl lipase by at least a hundred times. This step does not directly involve the ester substrate.Thus, it is suggested that a part of the activation of lipase at interfaces may be due to a conformational change resulting from adsorption.
124 citations
TL;DR: The complete inhibition of triglyceride removal by an antiserum prepared against adipose tissue LPL demonstrates that the NaCl-inhibited, serum-activated lipase prepared by affinity chromatography on heparin-Sepharose and concanavalin A-SepHarose columns is the enzyme responsible in vivo for the catabolism of VLDL triglyceride.
111 citations
TL;DR: The studies emphasize the necessity for differentiating between triglyceride lipase activity of hepatic and extrahepatic origin in evaluating patients with impaired triglyceride metabolism.
109 citations
TL;DR: From this study with monolayers, it is concluded that activity of lipolytic enzymes used as tools for probing biological membranes will be greatly influenced by the physiochemical nature of the membrane-water interface.
101 citations
TL;DR: Taurodeoxycholate enables the adsorption of lipase in the presence of bile salt, thereby reversing the inhibition of lipolysis, and colipase exerts small positive effects on lipase stability and catalytic activity.
91 citations
TL;DR: Findings clearly indicate the potential applicability of acylthioester analogs of substrates for phospholipase, lysophospholipases, and lipases in continuous spectrophotometric assays for lipolytic enzymes.
87 citations
TL;DR: Since DP-lipase is still fully active on dissolved p-nitrophenyl acetate, the serine residue is more likely implicated in the recognition and the binding to interfaces, as confirmed by the inability of DP- lipase to be adsorbed on siliconized glass beads.
Abstract: Reaction of lipase with diethyl pyrocarbonate results in the modification of three histidine residues. One is highly reactive, although without affecting the activity, while the two others react more slowly with a concomitant loss of activity on both dissolved and emulsified substrates. As previously shown, lipase can also be modified either by reaction of five carboxyl groups with carbodiimide (5N-lipase) or by esterification of one serine residue with diethyl p-nitrophenyl phosphate (DP-lipase). In the three cases, the activity on emulsified substrates is abolished. The modification of histidine residues results also in a loss of activity on dissolved substrates, suggesting that the essential histidine is at (or close to) the active site. The ability of lipase to be adsorbed on siliconized glass beads is not impaired in this reaction. By contrast, 5N-lipase is still able to hydrolyze dissolved monomeric substrates and to adsorb on siliconized glass beands. Therefore, the essential carboxyl group is assumed to play an important role in the interfacial activation. Finally, since DP-lipase is still fully active on dissolved p-nitrophenyl acetate, the serine residue, which has been previously suggested to be the acylable one, is more likely implicated in the recognition and the binding to interfaces, as confirmed by the inability of DP-lipase to be adsorbed on siliconized glass beads.
TL;DR: Lipases from Aspergillus niger and Rhizopus delemar hydrolyzed triolein and produced l,2 (2,3)-diolein and 2-monoolein, while lipases from Geotrichum candidum Link and Penicillium cyclopium Westring attacked the fatty acid chains regardless of their positions.
Abstract: Lipases from Aspergillus niger and Rhizopus delemar hydrolyzed triolein and produced l,2 (2,3)-diolein and 2-monoolein. These two lipases appears to have strong specificity towards the outer chains of the triglyceride. Comparing the proportions of fatty acids in position 1 (3) of cocoa butter with proportions of fatty acids liberated after limited hydrolysis of cocoa butter, it becomes clear that these two lipases do not hydrolyze the ester bond in position 2 of the triglyceride.On the other hand, lipases from Geotrichum candidum Link and Penicillium cyclopium Westring attacked the fatty acid chains regardless of their positions. Geotrichum candidum lipase liberated oleic acid and palmitic acid in preference to stearic acid from cocoa butter.
TL;DR: In this article, a two-phase reaction system with taurodexycholate prevents the adsorption of pancreatic lipase B to the nonaqueous phase, and the protein cofactor reverses the inhibitory effects of bile salt by providing a high affinity binding site at the interface for the lipase-(bile salt)4 complex.
TL;DR: The activity of lipop protein lipase isolated from rat postheparin plasma has been determined with synthetic lipids, in the presence and absence of apoprotein of the natural substrate very low density lipoprotein, as a function of medium ion-pair concentration of a number of different inorganic salts.
TL;DR: The results of subcellular fractionation studies showed that there was no significant enrichment of the acid lipase in any fraction and the microsomes showed three lipolytic activities, optimal at pH 8.0-8.6, which catalyzed the hydrolysis of both diacylglycerol and monoacyl Glycerol.
TL;DR: A galactolipid lipase from primary bean (Phaseolus vulgaris) leaves has been used to partially deplete spinach chloroplast inner membranes of their galactsolipids, and electron microscopy of chloroplasts treated with the lipase in the presence of bovine serum albumin showed that membrane stacking was partially maintained.
Abstract: A galactolipid lipase from primary bean ( Phaseolus vulgaris ) leaves has been used to partially deplete spinach chloroplast inner membranes of their galactolipids. Chloroplasts treated with the lipase in the absence of bovine serum albumin lost 91% of their monogalactosyl diglyceride, 83% of their digalactosyl diglyceride, all of their phosphatidyl choline, but none of their sulfolipid. Electron microscopy of this sections revealed that the treated chloroplasts were greatly enlarged and lacked membrane stacking. Linolenic acid had similar effects on the structure of the chloroplasts. Chlorophyll, carotenoids, and coupling factor 1 remained bound to the treated membranes. To minimize the inhibition of phosphorylation and electron flow by fatty acids released by the lipase, bovine serum albumin (15-24 mg/ml) was added to the lipase incubation mixtures. Bovine serum albumin inhibited the extent, but not the initial rate, of fatty acid release by the lipase. Electron microscopy of chloroplasts treated with the lipase in the presence of bovine serum albumin showed that membrane stacking was partially maintained. Chloroplasts treated with lipase under these conditions retained about 30% of their monogalactosyl diglyceride, 50% of their digalactosyl diglyceride and phosphatidyl choline. The sulfolipid and phosphatidyl glycerol contents were unchanged. Electron flow through photosystems I and II with artificial electron donors and acceptors was not affected by lipase treatment in the presence of bovine serum albumin. In contrast, oxygen evolution and phosphorylation were partially inhibited. These reactions are also very sensitive to fatty acids and it is possible that the inhibition is the result of interaction of fatty acids with the membrane prior to their binding to bovine serum albumin. In view of the irreversible inactivation of electron flow and phosphorylation by fatty acids, it is difficult to assess the role of galactolipids in these processes when a specfic lipase is used to deplete the membrane.
TL;DR: Human milk contains a serum stimulated lipoprotein lipase with many of the characteristics of the enzyme in bovine milk, as well as an enzyme stimulated by bile salts which resembles the sterol ester hydrolase of rat pancreatic juice.
TL;DR: In this paper, a 1:1 mixture of cis - and trans -3,5-diacetoxycyclopent-1-ene (1) was asymmetrically hydrolysed by baker's yeast to give trans-3(R )-acetoxy-5( R )-hydroxycyclopent -1-en-en.
TL;DR: Three distinct potato (Solanum tuberosum) lipid acyl-hydrolases have been isolated and characterized and may reasonably be considered an esterase.
Abstract: Three distinct potato (Solanum tuberosum) lipid acyl-hydrolases have been isolated and characterized. Nonfluorescent esters of the fluorescent alcohols, N-methylindoxyl and N-methylumbelliferone, have been used as convenient substrates for lipid acyl-hydrolase estimation. Enzyme I has been shown to be a neutral lipase which favors glyceryl triolein over the di- and monoolein, which shows no activity with phospho- and galactolipids and which favors long chain fatty acid esters of N-methylindoxyl over the butyrate ester. Enzyme II, while attacking glyceryl mono- and diolein, as well as favoring the butyrate ester of N-methylindoxyl over the myristate ester, is basically a phospholipid and galactolipid acyl-hydrolase. Enzyme III may reasonably be considered an esterase, since it hydrolyzes glyceryl monoolein exclusively among the neutral lipids, shows minimal activity on phospho- and galactolipids, and hydrolyzes N-methylindoxylbutyrate exclusively compared with N-methylindoxyl-myristate.
TL;DR: In substrate specificity, the enzyme exhibited a high specificity toward triglycerides having short-carbon chain fatty acids, although it was capable of hydrolyzing the ester bonds in the rice and olive oil.
Abstract: A species of rice bran lipase (lipase II) was purified by ammonium sulfate precipitation, followed by successive chromatographies on DEAE-cellulose, Sephadex G–75 and CH-Sephadex C–50. Both polyacrylamide disc electrophoresis and ultracentrifugation demonstrated that the enzyme protein is homogeneous. The isoelectric point of the enzyme was 9.10 by ampholine electrophoresis. The sedimentation coefficient of the enzyme was evaluated to be 2.60 S, and the molecular weight to be 33,300 according to Archbald’s method. The enzyme showed the optimum pH between 7.5 and 8.0, and the optimum temperature at about 27°C. It was stable over the pH range from 5 to 9.5 and below 30°C. In substrate specificity, the enzyme exhibited a high specificity toward triglycerides having short-carbon chain fatty acids, although it was capable of hydrolyzing the ester bonds in the rice and olive oil.
TL;DR: A modification of this new medium enables a search to be made for lipolytic bacteria in soil to demonstrate the lipase activity of bacteria in foods.
Abstract: A medium containing tributyrin stabilized with polyvinyl alcohol was used to demonstrate the lipase activity of bacteria in foods. A modification of this new medium enables a search to be made for lipolytic bacteria in soil.
TL;DR: The data presented in this report suggest that the decreased C-II activated lipoprotein lipase may be further aggravated by increased ApoE levels, since this enzyme is involved in the catabolism and removal of lipoproteins.
Abstract: Apolipoprotein E (ApoE; “arginine-rich” polypeptide) strongly inhibited both C-I and C-II activated lipoprotein lipases but not the protamine insensitive triglyceride lipase. Inhibition of lipoprotein lipases by ApoE in contrast to inhibition by C-III was not reversed to any significant extent by either increased concentration of activator or triglyceride in the substrate. Our previous studies have shown that in a type III hyperlipoproteinemia (broad-β-disease) a post-heparin plasma lipoprotein lipase activated by C-II polypeptide of lipoprotein C is decreased in enzyme activity and exhibits an impaired ability to hydrolyze triglycerides in very low density lipoproteins. Type III patients are characterized by elevated concentrations of ApoE in the serum. The data presented in this report suggest that the decreased C-II activated lipoprotein lipase may be further aggravated by increased ApoE levels. Since this enzyme is involved in the catabolism and removal of lipoproteins, decreased activity of C-II activated lipoprotein lipase may presumably be responsible for increased ApoE.
TL;DR: A totally enzymatic method for determination of serum triglycerides (triacylglycerols) specifically adaptable to the CentrifiChem system is described, unaffected by phosphatase and a considerably simplified reagent is used.
Abstract: We describe a totally enzymatic method for determination of serum triglycerides (triacylglycerols) specifically adaptable to the CentrifiChem system. The method involves lipolysis with lipase from Rhizopus arrhizus alone and quantitation of the resulting glycerol with glycerol dehydrogenase in a kinetic, fixed-time mode. Hydrolysis by the lipase is complete, for concentrations up to at least 5.0 g/liter, in 10 min at room temperature. The unfavorable equilibrium for the oxidation of glycerol is overcome by increasing the pH and adding excess NAD+. Under these conditions the glycerol determination is linear to at least 4.0 g of glycerol per liter, as triglyceride. The test exhibits acceptable accuracy and precision, and results correlate well with those by an alternative totally enzymatic procedure. The present method is unaffected by phosphatase and a considerably simplified reagent is used.
TL;DR: Chylomicrons isolated form rat intestinal lymph were incubated with plasma to determine protein transfer, reaction rate with purified lipoprotein lipase, and content of lipase cofactor, and results are discussed in the light of recent concepts of the regulation of lipop protein lipase activity.
TL;DR: In this paper, a model emulsion composed of butteroil emulsified with crude soy lecithin was used to investigate the effect of pseudomonas fluorescens hydrolyzed phospholipids adsorbed to fat globules.
TL;DR: The occurrence of lipase in serum and cells suggests that suitable substrates could be degraded by hydrolysis extracellularly as well as within phagocytes.
01 Jan 1976
TL;DR: Efficient fat absorption requires the rapid flux of poorly soluble and insoluble molecules through the very thick unstirred water layer coating the absorptive mucosa of the small intestine.
Abstract: Efficient fat absorption requires the rapid flux of poorly soluble and insoluble molecules through the very thick unstirred water layer coating the absorptive mucosa of the small intestine. Fat digestion involves a chemical event — the hydrolysis of ester lipids by lipase and a non-specific esterase; and a physical event — the micellar dispersion of these lipolytic products by bile acids. For some lipids, e.g. trioctanoin, only chemical hydrolysis is necessary since the digestive products are water soluble. Other insoluble lipids, such as cholesterol, are not altered chemically during digestion, but micellar solubilization is required for absorption.
TL;DR: A proteinous inhibitor of lipase was purified from soybean cotyledons by the procedures of ammonium sulfate fractionation, gel-filtration on Sephadex G–150 column, DEAE-cellulose column chromatography and isoelectric focusing and the mode of inhibition is discussed.
Abstract: A proteinous inhibitor of lipase was purified from soybean cotyledons by the procedures of ammonium sulfate fractionation, gel-filtration on Sephadex G–150 column, DEAE-cellulose column chromatography and isoelectric focusing. The inhibitor obtained by gelfiltration was separated into three active components, D–1, D–2 and D–3, by DEAE-cellulose column chromatography. The D–3 fraction after isoelectric focusing was homogeneous judged from disc electrophoresis. The inhibitory activity was more stable against treatments of heating and Pronase when the D–3 fraction was preincubated with substrate than without substrate. The extent of inhibition was varied by changing the order of addition of reactants and condition of substrate. From these results, the mode of inhibition is discussed.
TL;DR: It was elucidated that the hydrophobic bond play a major role in the adsorption of the lipase on substrate or hydrophilic surface and was treated in the Lineweaver-Burk's plot.
Abstract: The lipase from Chromobacterium was adsorbed on glass beads which was coated with olive oil, liquid paraffin or silicone oil. These adsorption was treated in the Lineweaver-Burk's plot and characters of the adsorption were similar each other regardless of their chemical structure of hydrophobic materials. On the other hand, esterase from porcine liver was not adsorbed on hydrophobic glass beads. The interaction between the lipase and hydrophobic surface conformed to the Langmuir's adsorption isotherm with a dissociation constant K=1.4×10-7M. At saturation of the surface with the lipase each protein molecule occupies an average area of 4500 A2 per molecule. The lipase adsorbed on hydrophobic surface did not inactivated but activated about 3-fold. It was elucidated that the hydrophobic bond play a major role in the adsorption of the lipase on substrate or hydrophobic surface.