Showing papers on "Lipase published in 1981"
TL;DR: The need to investigate further the effects of dietary fiber on digestion and absorption in the small intestine to understand fully its effects on metabolism is emphasized.
169 citations
TL;DR: It is suggested that intragastric lipolysis is probably of major importance in the newborn and especially in the premature infant where it compensates not only for low pancreatic lipase, but in addition, helps to overcome the temporary bile salt deficiency through the formation of amphiphilic reaction products.
Abstract: We have measured lipolytic activity in gastric aspirates obtained at birth in a group of 142 infants. The infants ranged in gestational age from 26 to 41 wk. Lipolytic activity, measured by the hydrolysis of long chain triglyceride ([tri-(3)H]oleate), and expressed as nanomoles FFA per milliliter gastric aspirate per minute was 333+/-66 in 55 small premature infants (gestational age 26-34 wk and body wt 750-2,000 g) and 558+/-45 in a group of 87 larger infants (gestational age 35-41 wk and body wt 2,020-4,000 g). No activity was detected in seven infants with an unusually low pH in the gastric aspirate, 2.88+/-0.44 (compared with a mean pH level of 5.59+/-0.22 in the other 135 infants). Attempts to characterize this lipase showed that it has a molecular weight of 44-48,000, pH optimum of 3.0-5.0, that FFA acceptors (albumin) stimulate activity, whereas bile salts, taurocholate and glycocholate, cause marked inhibition at concentration >3 mM. Our survey shows that enzyme activity is present as early as 26 wk of gestation, increases with gestational age, and has the same characteristics throughout gestation. The data show that the lipase in gastric aspirates differs from pancreatic lipase, but closely resembles human and rat lingual lipase. Because the lipase has a low pH optimum and does not require bile salts, it can act in the stomach where it initiates the hydrolysis of dietary fat. We suggest that intragastric lipolysis is probably of major importance in the newborn and especially in the premature infant where it compensates not only for low pancreatic lipase, but in addition, helps to overcome the temporary bile salt deficiency through the formation of amphiphilic reaction products.
163 citations
TL;DR: It was concluded that the rigidity of the aromatic ring in the CPE chains strongly influenced their susceptibility to hydrolysis by this lipase.
Abstract: Copolyesters (CPEs) prepared by the transesterification reaction between aromatic and aliphatic polyesters were hydrolyzed by Rhizopus delemar lipase. The susceptibility of CPEs to hydrolysis by this lipase dropped off rapidly during the initial stage of the transesterification reaction and increased gradually as the reaction proceeded. The susceptibility to hydrolysis decreased with increase in aromatic polyester content. It was concluded that the rigidity of the aromatic ring in the CPE chains strongly influenced their susceptibility to hydrolysis by this lipase.
157 citations
TL;DR: The complete primary structure of a lipase (triacylglycerol hydrolase; EC 3.1.3) is presented for the first time and few similarities which might be significant were detected between the environment and relative position of certain half cystines in lipase and colipase, as well as between two tyrosine-rich regions existing in both proteins.
150 citations
TL;DR: The bile-salt-stimulated lipase was purified from human whey by chromatography on heparin-Sepharose and Affi-Gel blue and was inhibited by diisopropylfluorophosphate, which bound to the purified enzyme in a molar ratio of 0.85 mol/mol.
Abstract: The bile-salt-stimulated lipase was purified from human whey by chromatography on heparin-Sepharose and Affi-Gel blue. The purified enzyme gave a single band with a molecular weight of 90000 on dodecylsulphate/polyacrylamide gels and this band accounted for at least 98% of the protein on the gel. An antiserum to the purified lipase completely inhibited the enzyme activity and gave a single precipitate against human whey and purified lipase. The bile-salt-stimulated lipase was inhibited by diisopropylfluorophosphate, which bound to the purified enzyme in a molar ratio of 0.85 mol/mol. The lipase is a glycoprotein with a high content of acidic amino acid residues and an isoelectric point of around 4. Proline constitutes more than 10% of the total amino acid residues. The purified lipase has a turnover number of around 150 s−1.
131 citations
TL;DR: The ultramicro (1-microL samples) assay of serum or plasma triglycerides that is potentially applicable to 1-nL samples and to isolated cells is described, and performance characteristics compare well with those of traditional triglyceride assays.
Abstract: The ultramicro (1-microL samples) assay of serum or plasma triglycerides that we describe here is potentially applicable to 1-nL samples and to isolated cells. This technically simple method involves only three reactions: (a) enzymic hydrolysis with lipase and alpha-chymotrypsin; (b) conversion by glycerol kinase of the liberated glycerol and of adenosine triphosphate added in excess to glycerol-1-phosphate and to adenosine diphosphate; and (c) assay of the residual adenosine triphosphate by the luciferin-luciferase reaction. The assay was optimized with respect to glycerol kinase, buffer, pH, temperature, and adenosine triphosphate. Performance characteristics compare well with those of traditional triglyceride assays.
118 citations
TL;DR: The immunochemical, molecular and kinetic properties of bile salt-stimulated lipase and carboxyl ester hydrolase are compared and it is concluded that the 2 enzymes are very similar but not identical.
111 citations
TL;DR: The results suggest that the decrease of HDL cholesterol observed during treatment with progestins is related to the androgenic activity of the steroid used, and that the change in HDL (HDL2) is caused by androgen-induced increase of hepatic lipase activity.
90 citations
TL;DR: It is proposed that a principal pathway for degradation of phosphatidylcholine, particularly during brain ischemia, is by reversal of cholinephosphotransferase, followed by hydrolysis of diacylglycerols by the lipase.
89 citations
TL;DR: The presence of NaCl-resistant, neutral triacylglycerol hydrolase (lipase) activity in rat adrenal gland, ovary and testis was studied and indicated that the lipase is extracellularly located and is similar to 'liver' lipase.
Abstract: The presence of NaCl-resistant, neutral triacylglycerol hydrolase (lipase) activity in rat adrenal gland, ovary and testis was studied Both adrenals and ovaries but not testes were found to contain such a lipase The activity of the enzyme in the adrenal gland was lowered during cortisol treatment and hypothyroidism An elevated adrenal lipase activity was found during hyperthyroidism Pseudo-pregnant and lactating rats had higher ovarian lipase activities than cyclic rats Ovarian lipase activity in lactating rats was positively correlated with the serum concentrations of progesterone and of 20 alpha-hydroxyprogesterone and negatively correlated with the high-density-lipoprotein non-esterified cholesterol concentration The lipase activity of adrenals and of ovaries was largely releasable from these organs by heparin and could be inhibited by an antibody against heparin-releasable liver lipase This indicated that the lipase is extracellularly located and is similar to ‘liver’ lipase A possible role of this lipase in adrenals and ovaries is discussed
84 citations
TL;DR: Hormone-sensitive lipase, the most characteristic and functionally important enzyme of adipose tissue, has been characterized in differentiated 3T3-L1 cells and should be a valuable model system in which to study regulation of hormone-sensitivelipase, particularly its long-term regulation.
Abstract: Differentiation of 3T3-L1 fibroblasts to adipocyte-like cells was accompanied by a 19-fold increase in neutral triglyceride lipase activity, a 12-fold increase in diglyceride lipase activity, a 10-fold increase in monoglyceride lipase activity, and a 280-fold increase in cholesterol esterase activity. In contrast, acid acylhydrolase activities did not increase during differentiation. The rate of glycerol release from unstimulated intact cells increased by more than 1 order of magnitude upon differentiation. Isoproterenol (1 microM) and 1-methyl-3-isobutylxanthine (0.1 mM) further stimulated this rate of glycerol release 3-fold. The neutral triglyceride lipase activity in cell-free preparations of differentiated cells was activated 105% by cyclic AMP-dependent protein kinase. Neutral cholesterol esterase, diglyceride lipase, and monoglyceride lipase were also activated (117%, 10%, and 37+, respectively) by cyclic AMP-dependent protein kinase. In contrast, protein kinase had no effect on any of the four lysosomal acid acylhydrolase activities. Thus, hormone-sensitive lipase, the most characteristic and functionally important enzyme of adipose tissue, has been characterized in differentiated 3T3-L1 cells. The 3T3-L1 cell should be a valuable model system in which to study regulation of hormone-sensitive lipase, particularly its long-term regulation.
TL;DR: The position in porcine pancreatic lipase of the serine reacting specifically with emulsified or micellar diethyl p-nitrophenyl phosphate has been investigated and this serine which appears to be involved in lipase adsorption to insoluble triglyceride interfaces is at position 152 in the enzyme chain.
TL;DR: Using doubly labelled phosphatidylcholine, a specificity, A1, was described for the two cationic lipases, which are unaffected by N-ethylmaleimide, diisopropylfluorophosphate and p-bromophenacylbromide, and are insensitive to EDTA and slightly inhibited by CaCl2 and MgCl2, whereas sodium deoxycholate is required for maximal activity.
Journal Article•
TL;DR: It was concluded that determination of serum amylase activity without knowledge of serum lipase activity was of little value to diagnose pancreatitis and that high values were often, but not always, diagnostic for pancreatitis.
Abstract: To determine the usefulness of information provided by measurement of serum amylase activity in the evaluation of dogs for pancreatitis, the relationship of amylase activity to lipase activity in 713 paired serum samples was investigated by statistical analysis. Little change in mean amylase concentration was found until lipase values exceeded 800 U/L. The ranges of amylase activity (mean +/- 2 SD) were essentially the same for dogs with no pancreatitis (0 to 100 U of lipase activity/L) as for dogs with a high probability for the disease (700 to 799 U of lipase activity/L), 0 to 4,029 U/L and 857 to 4,869 U/L, respectively. Pathologic findings from biopsy and necropsy reports from 92 dogs for which serum lipase determinations were done indicated that serum lipase increased not only with pancreatitis, but also with other medical problems, such as renal and hepatic disease. It was concluded that determination of serum amylase activity without knowledge of serum lipase activity was of little value to diagnose pancreatitis. High amylase activity was not specific for pancreatitis and low amylase activity could not rule out the disease. The results of this study also showed that low serum lipase values almost always eliminated the possibility of pancreatitis and that high values were often, but not always, diagnostic for pancreatitis.
TL;DR: The results taken together suggest that colipase binds to certain bile salt-PC associations independent of whether the aggregates are located at the surface of a triglyceride particle as a monolayer or in the bulk aqueous phase as mixed micelles.
Abstract: Mixed dihydroxy bile salt-phosphatidylcholine (PC) micelles can inhibit the hydrolysis of gum arabic-stabilized long-chain triglyceride emulsions by 10(-8) to 10(-9) M concentrations of human pancreatic lipase and colipase. Trypsin treatment of this colipase preparation did not reverse the inhibition, suggesting that procolipase, as a possible contaminant, was not the inhibitory factor. Human biliary phospholipid-cholesterol liposomes, isolated by gel filtration and redissolved in bile salt solutions, inhibited lipolysis to the same degree as solutions of bile salt containing purified PC. The degree of inhibition depended principally on the species of bile salt present (e.g., taurochenodeoxycholate greater than taurodeoxycholate greater than tauroursodeoxycholate greater than taurocholate). In the absence of bile salt, PC (0.4 mM) liposomes alone were not inhibitory over the physiological time range studied. Bile salt solutions of phosphatidylethanolamine or sphingomyelin also inhibited lipase activity, whereas those containing oleyl alcohol, oleyl aldehyde, oleic acid, and lyso-PC did not. PC molecules were found to partition between the triglyceride emulsion interface and the bulk aqueous phase. Full reversal of inhibition occurred in the presence of phospholipase A2, which hydrolyzed the phospholipids to lysolecithin and fatty acids. Mixed bile salt-phospholipid micelles caused marked decrease in the binding of lipase and colipase to the triglyceride substrate and displaced the proteins into the aqueous phase. The results taken together suggest that colipase binds to certain bile salt-PC associations independent of whether the aggregates are located at the surface of a triglyceride particle as a monolayer or in the bulk aqueous phase as mixed micelles.
TL;DR: Kinetic studies indicated the formation of an enzyme-activator-substrate ternary complex through a random pathway and the enzyme reaction was demonstrated to follow a rapid equilibrium random uni bi mechanism.
TL;DR: Analysis of the reaction products from the hydrolysis of triolein by P. acnes lipase did not demonstrate an accumulation of 2-monoolein which suggested that the enzyme did not exhibit a positional specificity for the 1-position of the triacylglycerol.
Abstract: Lipase from Propionibacterium acnes has been purified 4800-fold from crude culture supernatant. The purified enzyme preparation had no assayable protease, hyaluronate lyase or acid phosphatase activities. The molecular weight of the lipase was 46,770 as determined by gel filtration. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed a major protein component (mol. wt 41,190) together with two minor protein components (mol. wt 67,000 and 125,900). The lipase had a pH optimum of 6.8, was most stable in the pH range 5.0 to 6.0 and was completely inactivated after 30 min at 60 degrees C. The lipase hydrolysed trilaurin, triolein, trimyristin and tripalmitin at decreasing rates and did not exhibit phospholipase activity. Analysis of the reaction products from the hydrolysis of triolein by P. acnes lipase did not demonstrate an accumulation of 2-monoolein which suggested that the enzyme did not exhibit a positional specificity for the 1-position of the triacylglycerol. Crude lipase preparations contained an aggregated high molecular weight form of the enzyme which was eluted with the void volume from Sephadex G-200. This aggregated form was dissociated to produce the lower molecular weight lipase species by subsequent dialysis and elution from Sephadex G-200 using buffer with a higher ionic strength.
TL;DR: In this article, a packed bed reactor containing 1 g of mycelia fed at 1 mL/min with a solution of 2.5% (w/v) olive oil in di-isopropyl ether gave a fatty acid yield of 45% at 30°C.
Abstract: Continuous hydrolysis of triglyceride in organic solvent systems using Rhizopus arrhizus mycelia as a source of insolubilized lipase has been studied in packed-bed and stirred-tank reactors. Typically a packed bed reactor containing 1 g of mycelia fed at 1 mL/min with a solution of 2.5% (w/v) olive oil in di-isopropyl ether gave a fatty acid yield of 45% at 30°C. The optimum water concentration was found to be 0.17% (w/v) except under conditions of high oil feed concentration and high yield where no optimum was established. No temperature optimum was observed over the range 20–55°C. Calculated activation energies of 13–20 kJ/mol, depending on temperature, were lower, while Km(app) values of 0.1–0.3M were higher than those for hydrolysis in conventional aqueous emulsion systems. No evidence of any significant diffusional limitation, which could account for these values, was obtained. The mycelia showed a loss of activity of 0.6–1.0%h at 30°C. The packed bed proved markedly superior to the stirred tank for this system.
TL;DR: Results support non-random stereochemical fatty acid and molecular species distribution for all TG's analyzed and show loss of medium chain fatty acids during digestion, producing a shift to a larger average molecular weight TG than present in milk.
TL;DR: Human serum is measured and the rate of phospholipase A activity of purified human heparin-releasable liver lipase with isolated HDL-2 and HDL-3 is measured, providing further evidence for a role of liverlipase in the degradation of HDL- 2.
TL;DR: Tetracycline, declomycin and erythromycin, in concentrations lower than the minimal inhibitory dosages, were shown to inhibit lipase production by Propionibacterium acnes in vitro.
Abstract: Summary
Tetracycline, declomycin and erythromycin, in concentrations lower than the minimal inhibitory dosages, were shown to inhibit lipase production by Propionibacterium acnes in vitro.
TL;DR: Kinetic studies of the inhibition of horse lipase activity by bile salts and of reactivation by pure colipase from three species allowed to calculate the apparent dissociation constant of the lipase-colipase complex in the presence of the substrate (triolein).
TL;DR: It was found that bile salts, even at high concentrations, stimulated triglyceride hydrolysis of such phospholipase-treated globules by pancreatic lipase also in the absence of colipase.
Abstract: Human milk fat globules were used to explore how dietary triglycerides are hydrolyzed by pancreatic lipase. These triglycerides were hydrolyzed very slowly by lipase alone as if the surface layer of proteins and phospholipids impeded the action of the enzyme. The inhibition of lipase activity could be overcome by addition either of colipase or of pancreatic phospholipase A2. Colipase enhanced triglyceride hydrolysis in a dose-dependent manner whether bile salts were present or not. Bile salts had no effect on the activity of pancreatic lipase alone but further enhanced the activity at all concentrations of colipase tested. Bile salts were a prerequisite to relieve inhibition of lipase activity by phospholipase A2. Human milk fat globules exposed to phospholipase A2 should be representative of a physiological substrate for pancreatic lipase. A major new observation was that bile salts, even at high concentrations, stimulated triglyceride hydrolysis of such phospholipase-treated globules by pancreatic lipase also in the absence of colipase.
TL;DR: This chapter discusses assay of enzymes of lipid metabolism with colored and fluorescent derivatives of natural lipids, using a solubilized preparation of enzyme from a lysosome-enriched preparation of rat brain and extracts of skin fibroblasts of normal humans and Niemann-Pick patients and of amniotic cells.
Abstract: Publisher Summary This chapter discusses assay of enzymes of lipid metabolism with colored and fluorescent derivatives of natural lipids. Fatty acid containing the colored or fluorescent probe was condensed with cholesterol, or glycerol, or deacylated sphingolipid, or glycerophospholipid. The colored or fluorescent lipid product was then isolated from the reaction mixture and purified by column or by thin-layer chromatography. The yellow substrates are dispersed and incubated with lipase. The reaction is terminated with alkaline ethylene glycol, and the unreacted neutral substrate is extracted into benzene. Acid is then added, the fatty acid produced by enzymatic hydrolysis is extracted into benzene, and its absorbance is determined spectrophotometrically. The activity of the lysosomal sphingomyelinase was determined at pH 5.0 using a solubilized preparation of enzyme from a lysosome-enriched preparation of rat brain, as well as extracts of skin fibroblasts of normal humans and Niemann-Pick patients and of amniotic cells. Fluorescent sphingomyelin and nonfluorescent sphingomyelin are mixed in the molar ratio used in the assay procedure, and the concentration is estimated by determining the phosphorus content.
TL;DR: The present results indicate that a special site on the lipoprotein lipase might be involved in the facilitation of cellular uptake of cholesteryl ester, which could contribute to the atherogenic potential of dietary chylomicrons, as has been proposed by the Zilversmit hypothesis.
TL;DR: The in vivo cleavage of medium and long-chain triacylglycerol substrates in the stomach of newborn rats with ligated pylorus and oesophagus and excised pancreas and lingual glands indicates that gastric lipase is a separate enzyme entity which may participate in fat digestion during the postnatal period in the moderately acid stomach milieu and then in the duodenum, upon activation with bile salts.
TL;DR: The ability of the enzymes used to degrade the appropriate substrate was confirmed by incubating each lipase with a mixture of phosphatidylcholine, phosph atidylethanolamine, phosphAtidylserine, and sphingomyelin for 15 min at 37 OC.
TL;DR: The results indicated that these three procedures are equally suitable for the determination of I and II from normolipidemic subjects, and the column-chromatographic procedure is the preferred method for measuring lipase concentrations in post-heparin plasma of hyperlipidemic patients.
Abstract: A modified heparin-Sepharose affinity chromatography procedure (Boberg et al., J. Lipid Res. 18:544-547, 1977) was developed to determine two different triglyceride lipase activities in human post-heparin plasma: hepatic triglyceride lipase (I) and lipoprotein lipase (II). With this procedure, lipoproteins were separated from the eluted lipases. The total lipolytic activity of II was eluted from heparin-Sepharose by heparin. The use of heparin as eluting agent prevents the partial inhibition of II, in contrast to the procedure based on elution of II with a high concentration of NaCl. In a comparative study with the modified heparin-Sepharose affinity column chromatography, the immunochemical and protamine sulfate inhibition procedures, the results indicated that these three procedures are equally suitable for the determination of I and II from normolipidemic subjects. However, because of possible interference by plasma, the column-chromatographic procedure is the preferred method for measuring lipase concentrations in post-heparin plasma of hyperlipidemic patients. The II activity of post-heparin plasma from normolipidemic subjects was not significantly age-(20-39 and 40-60 years) or sex-related. I activity was also not significantly different with respect to age, but was significantly greater in men than in women.
Journal Article•
TL;DR: The results demonstrate that these hormones regulate the activity of the hormone-sensitive lipase, ie the rate of lipolysis in the adipocytes, by changes of the degree of phosphorylation of the enzyme.
Abstract: Hormone-sensitive lipase has been purified from rat adipose tissue to almost 50 per cent protein purity and partially characterized. The isolated enzyme can be phosphorylated by ATP-Mg2+ in the presence of the catalytic subunit of cyclic AMP-dependent protein kinase from the same tissue. Its activity towards emulsified triglyceride is thereby increased two-fold. The enzyme is phosphorylated also in the intact adipocyte, verifying the physiological relevance of the findings with the isolated enzyme. Noradrenaline causes a rapid increase in phosphorylation of the enzyme in intact adipocytes, immediately followed by a marked increase of its activity. Addition of dibutyryl-cyclic AMP to the adipocytes causes the same effects. The extent of phosphorylation of the enzyme after maximal noradrenaline stimulation of the adipocytes is rapidly decreased by insulin addition in close association with inhibition of the lipase activity. The results demonstrate that these hormones regulate the activity of the hormone-sensitive lipase, ie the rate of lipolysis in the adipocytes, by changes of the degree of phosphorylation of the enzyme.