Triacylglycerol Lipase Activity Research Articles

A polylactic acid degrading lipase from Bacillus safensis: Characterization and structural analysis

A polylactic acid degrading triacylglycerol lipase (TGL) was identified from Bacillus safensis based on genome annotation and validated by real-time quantitative PCR. TGL displayed optimal activity at pH 9.0 and 55 °C. It maintained stability at pH 9.0 and temperatures 45 °C. The activity of TGL was found to benefit from the presence of potassium sodium ions, and low concentrations of Triton X-100. The TGL could erode the surface of polylactic acid films and increase its hydrophilicity. The hydrolysis products of polylactic acid by TGL were lactate monomer and dimer. TGL contains a classical catalytic triad structure of lipase (Ser77, Asp133, and His156) and an Ala-X-Ser-X-Gly sequence. Compared with some lipases produced by the same genus Bacillus, TGL is highly conserved in its amino acid sequence, mainly reflected in the amino acid residues that exercise the enzyme activity, including the catalytic activity center and the substrate binding sites.

Examination of the effects of triacylglycerol lipase on astaxanthin conversion in the black tiger prawn Penaeus monodon

The enzyme triacylglycerol lipase (TGL) catalyses the hydrolysis of triacylglycerols, and is characterized by catalytic esterification and ester exchange functionality. However, at present, there is comparatively little information regarding the sequences and functional validation of TGLs in crustaceans. In this study, we cloned the TGL1 gene of the black tiger prawn Penaeus monodon. The full-length cDNA of PmTGL1 comprises 1807 base pairs (bp), including an 80-bp 5′-untranslated region (UTR), a 149-bp 3′-UTR, and a 1578-bp open-reading frame (ORF), and encodes a putative 525-amino acid protein of 58.71 kDa with a theoretical isoelectric point of 4.81. Homology and phylogenetic tree analyses revealed that PmTGL1 is most closely related to the TGL of Penaeus chinensis, with which it clusters in a single group (similarity of up to 97.52%). Quantitative real-time PCR analysis further revealed that PmTGL1 is most highly expressed in the shrimp hepatopancreas. Although the expression of PmTGL1 was not significantly influenced by the differences in the background colour of the rearing pond, it was significantly promoted in response to dietary supplementation with astaxanthin. As an adipokinetic hormone in P. monodon, PmRPCH (red pigment-concentrating hormone) plays an important role in body colour changes and lipid metabolism. Based on our findings, we speculate that the PmTGL1 facilitates astaxanthin metabolism in P. monodon via the hydrolysis of esterified astaxanthin to yield free astaxanthin and that the activity of TGL in these shrimps is regulated via an adipokinetic hormone cascade.

Effect of Exposure to Soot on Activities of Alanine Transaminase, Gamma Glutamyl Transferase and Lipase among Cooks in Nnewi

Exposure to soot can lead to hepatic and pancreatic dysfunction. This study determined serum alanine transaminase (ALT), gamma-glutamyl transferase (GGT), and triacylglycerol lipase activities of cooks exposed to soot. Thirty (30) participants (cooks) were exposed to soot (test group), and thirty (30) participants not exposed to soot (control group) were recruited. Ethical approval was obtained from the Ethics committee of the Faculty of Health Sciences and Technology, Nnamdi Azikiwe University, and informed consent from the participants was obtained. Alanine transaminase, gamma-glutamyl transferase, and triacylglycerol lipase activities were determined using the spectrophotometric method while the Body mass index (BMI) was calculated using weight (kg)/height2 (m2). An Independent t-test was used for statistical analysis. The results showed that the mean serum activities of alanine transaminase (14.69±1.84), of cooks exposed to soot, were significantly higher compared with the control(12.83±0.94)(p<0.05). The mean serum activities of gamma-glutamyl transferase (7.81±4.08), of cooks exposed to soot, were significantly higher when compared with the control (3.54±2.00)(p<0.05). The mean serum activities of triacylglycerol lipase of cooks exposed to soot were significantly low compared with the control (p<0.05), while there was no significant difference in the BMI, systolic pressure, and diastolic pressure levels respectively in the test group, compared to the control. This study observed higher serum activities of alanine transaminase, gamma-glutamyl transferase, and low serum activity of triacylglycerol lipase among cooks exposed to soot, this suggests a predisposition to hepatic and pancreatic dysfunction in the cooks
 Keywords: Soot, alanine transaminase, gamma-glutamyl transferase, lipase enzymes

High Drying Temperature Accelerates Sunflower Seed Deterioration by Regulating the Fatty Acid Metabolism, Glycometabolism, and Abscisic Acid/Gibberellin Balance.

Sunflower seed storage is accompanied by the loss of seed vigor. Seed drying is a key link between seed harvest and seed storage; however, to date, the effect of seed drying on sunflower seed deterioration during storage remains unclear. The present study performed hot air drying for sunflower seeds with an initial moisture content of 30% to examine the manner in which drying temperature (35, 40, 45, 50, and 55°C) affects the drying performance and seed vigor following storage process (6 and 12 months). A drying temperature of 40°C was evidently safe for sunflower seeds, whereas the high drying temperatures (HTD, 45, 50, and 55°C) significantly lowered sunflower seed vigor by regulating the fatty acid metabolism, glycometabolism, and abscisic acid (ABA)/gibberellin (GA) balance. HDT significantly increased the seed damage rate and accelerated sunflower seed deterioration during natural and artificial aging process. Further biochemical analysis indicated that HDT significantly increased lipoxygenase and dioxygenase activities, leading to malonaldehyde and reactive oxygen species over-accumulation during storage. During early seed germination, HDT significantly inhibited fatty acid hydrolysis and glycometabolism by decreasing triacylglycerol lipase, CoA-SH oxidase, and invertase activities. Moreover, HDT remarkably increased ABA levels but reduced GA levels by regulating gene expressions and metabolic enzyme activities during early imbibitions. Cumulatively, the seed drying effect on sunflower seed vigor deterioration during the storage process may be strongly related to fatty acid oxidation and hydrolysis metabolism, toxic substance accumulation, and ABA/GA balance.

Molecular modeling, docking and dynamics analysis of lipid droplet associated enzyme Ypr147cp from Saccharomyces cerevisiae.

Ypr147cp of Saccharomyces cerevisiae was localized to lipid droplets. The recombinant Ypr147cp showed both triacylglycerol lipase and ester hydrolase activities. Knock out of YPR147C led to accumulation of TAG in ypr147cΔ when compared to wild type (WT). Transmission electron microscopic analysis of ypr147cΔ cells show increased lipid bodies. Moreover, the lipid profiling confirmed the accumulation of fatty acids derived from neutral and phospholipids in ypr147cΔ cells. Sequence analysis of Ypr147cp show the presence of an a/b hydrolase domain with the conserved GXSXG lipase motif. The YPR147c homology model was built and the modeled protein was analysed using RMSD and root mean square fluctuation (RMSF) for a 100 ns simulation trajectory. Docking the acetate, butyrate and palmitate ligands with the model confirmed covalent binding of ligands with the Ser207 of the GXSXG motif. Thus, Ypr147cp is a lipid droplet associated triacylglycerol lipase having short chain ester hydrolyzing capacity.

Screening and Analysis of Hypolipidemic Components from Shuangdan Capsule Based on Pancreatic Lipase

Background: Some natural pancreatic lipase inhibitors with fewer side effects are proposed. As a traditional Chinese medicine, Shuangdan Capsule (SDC) has been used for the treatment of higher lipid in blood, which is mainly composed by Radix Salviae and Peony skin. Objective: This work is aimed to investigate the molecular mechanism of the constituents from this SDC against metabolic disorders, the molecular flexibility and intermolecular interactional characteristics of these components in the active sites. Methods: The small molecules were obtained from the Traditional Chinese Medicine Database TCM database, the systems-level pharmacological database for Traditional Chinese Medicine TCMSP server was used to calculate the ADME-related properties. Autodock Vina was used to perform virtual screening of the selected molecules and to return energy values in several ligand conformations. The network parameters were calculated using the network analyzer plug-in in Cytoscape. Results: The most active six molecules are all enclosed by amino acids ASP79, TYR114, GLU175, PRO180, PHE215, GLY216 and LUE264, among which, hydrophobic interaction, hydrogen bond and repulsive forces play extremely important roles. It is worth noting that most of the local minima of molecular electrostatic potentials on van der Waals (vdW) surface are increased while the maxima negative ones are decreased simultaneously, implying that the electrostatic potential tends to be stable. From the topological analysis of the Protein-Protein Interaction (PPI) network, PNLIP related genes are also proved to be pivotal targets for hyperlipidemia, such as LPL, AGK, MGLL, LIPE, LIPF and PNPLA2. Further GO analysis indicated that lipophilic terpenoid compounds may reduce the blood lipid by taking part in the lipid catabolic process, the extracellular space and the cellular components of the extracellular region part and the triacylglycerol lipase activity. Conclusion: This study provides some useful information for the development and application of natural hypolipidemic medcines. Further pharmacologically active studies are still needed both in vivo and in vitro.

Effects of coated cysteamine on growth performance, carcass characteristics, meat quality and lipid metabolism in finishing pigs

This study was conducted to evaluate the effects of coated cysteamine (CCS) on growth performance, carcass characteristics, meat quality, and lipid metabolism in finishing pigs. A total of 160 pigs (62.12 ± 1.43 kg body weight) were randomly divided into 4 groups, with 4 pens per group and 10 pigs (5 gilts and 5 barrows) per pen. Pigs were fed a basal diet supplemented with 0, 100, 200, or 400 mg/kg CCS, corresponding to 0, 27, 54, or 108 mg/kg cysteamine, respectively. All pigs were given free access to feed and water for forty days. Average daily gain, average daily feed intake and feed to gain ratio were not affected by the CCS treatment. Supplemental CCS increased carcass lean ratio linearly (P < 0.05) and longissmus muscle area quadratically (P < 0.05), and the water-holding capacity as measured by 24 h drip loss was quadratically affected (P < 0.05) by CCS supplementation. The activity of hormone-sensitive lipase in subcutaneous adipose tissue was linearly increased (P < 0.001), while fatty acid synthase activity was linearly decreased (P < 0.05). Pigs fed CCS had a lower serum triacylglycerol (P < 0.001) level and lipase activity (P < 0.001), lower total cholesterol (P < 0.05) level, and a higher total protein (P < 0.001) and free fatty acids (P < 0.01) levels. In addition, CCS quadratically increased serum growth hormone (GH) (P < 0.001) level and quadratically affected somatostatin (SS) (P < 0.05) level. Consistently, significant effects of dietary CCS were observed on the mRNA expression of GH and SS in the anterior pituitary gland and the hypothalamus, respectively, where the intermediate CCS level showed the highest GH mRNA level and lowest SS mRNA level. The results indicate that dietary supplementation of CCS has beneficial effects on carcass characteristics and meat quality, and affects lipid metabolism in finishing pigs.

DAGL-Beta Functions as a PUFA-Specific Triacylglycerol Lipase in Macrophages

Here, we apply quantitative chemical proteomics and untargeted lipidomics to assign a polyunsaturated fatty acid (PUFA)-specific triacylglycerol (TAG) lipase activity for diacylglycerol lipase-beta (DAGLβ) in macrophages. We demonstrate that DAGLβ but not DAGLα is expressed and active in bone marrow-derived macrophages (BMDMs) as determined by activity-based protein profiling analysis of SILAC BMDMs. Genetic disruption of DAGLβ resulted in accumulation of cellular TAGs composed of PUFA but not saturated/low unsaturated fatty acid counterparts, which is recapitulated in wild-type macrophages treated with a DAGLβ-selective inhibitor. Biochemical assays with synthetic substrates confirm PUFA-TAGs as authentic DAGLβ substrates. In summary, our findings identify DAGLβ as a PUFA-specific TAG lipase in primary macrophages.

DAGL-Beta Functions as a PUFA-Specific Triacylglycerol Lipase in Macrophages

Here, we apply chemical proteomics and untargeted lipidomics to assign a novel polyunsaturated fatty acid (PUFA)-specific triacylglycerol (TAG) lipase activity for diacylglycerol lipase-beta (DAGLβ) in macrophages. We demonstrate that DAGLβ but not DAGLα is expressed and active in bone marrow-derived macrophages (BMDMs) as determined by DAGL-directed activity-based protein profiling (ABPP). Genetic disruption of DAGLβ resulted in accumulation of cellular TAGs composed of PUFA but not saturated/low unsaturated FA counterparts, which is recapitulated in wild-type macrophages treated with a DAGLβ-selective inhibitor. Biochemical assays with synthetic substrates confirm PUFA-TAGs as authentic DAGLβ substrates. In summary, our findings identify DAGLβ as a PUFA-specific TAG lipase in primary macrophages.

Saccharomyces cerevisiae lipid droplet associated enzyme Ypr147cp shows both TAG lipase and ester hydrolase activities.

Saccharomyces cerevisiae Ypr147cp was found localized to lipid droplets but the physiological role of Ypr147cp remains unknown. Sequence analysis of Ypr147cp revealed an α/β hydrolase domain along with the conserved GXSXG lipase motif. Recombinant Ypr147cp showed both triacylglycerol lipase and ester hydrolase activities. Knock out of YPR147C led to accumulation of TAG in ypr147cΔ when compared to wild type (WT). In addition, transmission electron microscopic analysis of ypr147cΔ cells revealed a greater number of lipid bodies, justifying the increase in TAG content, and the phenotype was rescued upon overexpression of YPR147C in ypr147cΔ. Moreover, the lipid profiling confirmed the accumulation of fatty acids derived from neutral and phospholipids in ypr147cΔ cells. Based on these results, Ypr147cp is identified as a lipid droplet associated triacylglycerol lipase along with an ester hydrolyzing capacity.

Effect of Teucrium polium (Lamiaceae) essential oil on digestive enzyme activities and energy reserves of Ephestia kuehniella (Lepidoptera: Pyralidae)

In the current study, the effects of Teucrium polium L. (Lamiaceae) essential oil (Tp EO) and α-pinene as a major component of this essential oil, were tested against Ephestia kuehniella Z. (Lep.: Pyralidae) for larvicidal activity, digestive enzymes and non-enzymatic (amount of macromolecules) responses. Concentrations of 4.91 and 10.66 μl/ml were determined as LC50 values for Tp EO and α-pinene, respectively. The activities of α-amylase, triacylglycerol lipase, general protease, serine proteases (trypsin and chymotrypsin-like), carboxy- and aminopeptidases significantly decreased when the larvae fed on the diet supplemented with Tp EO and α-pinene but significant increases were observed in elastase-like proteinase. The amount of protein, glycogen and triglyceride decreased in the treated larvae by both treatments. The results showed that the digestive enzymes and non enzymatic activities of the treated larvae were decreased compared to the control. Therefore, Tp EO and α-pinene are suggested as botanicals for controlling flour moth larvae.

Label-free measurement of the yeast short chain TAG lipase activity by ESI-MS after one-step esterification

Triacylglycerol (TAG) lipases hydrolyze ester bonds in TAG and release diacylglycerol (DAG), monoacylglycerol (MAG), and FA. We present a one-step chemical derivatization method for label-free quantification of a mixture of TAG, DAG, and MAG following lipase assay by ESI-MS. Because the ionization efficiencies of TAG, DAG, and MAG are not identical, lipase reaction products, DAG and MAG, are derivatized to TAG species by esterifying their hydroxyl groups using acyl chloride, whose acyl chain contains one less (or one more) -CH2 group than that of substrate TAG. This resulted in three TAG species that were separated by 14 Da from one another and exhibited similar ion responses representing their molar amounts in the mass spectra. A good linear correlation was observed between peak intensity ratios and molar ratios in calibration curve. This method enables simultaneous quantification of TAG, DAG, and MAG in lipase assay and, in turn, allows stoichiometric determination of the concentrations of FAs released from TAG and DAG separately. By applying this strategy to measure both TAG and DAG lipolytic activities of the yeast Tgl2 lipase, we demonstrated its usefulness in studying enzymatic catalysis, as lipase enzymes often show dissimilar activities toward these lipids.

Molecular characterization of human ABHD2 as TAG lipase and ester hydrolase.

Alterations in lipid metabolism have been progressively documented as a characteristic property of cancer cells. Though, human ABHD2 gene was found to be highly expressed in breast and lung cancers, its biochemical functionality is yet uncharacterized. In the present study we report, human ABHD2 as triacylglycerol (TAG) lipase along with ester hydrolysing capacity. Sequence analysis of ABHD2 revealed the presence of conserved motifs G205XS207XG209 and H120XXXXD125. Phylogenetic analysis showed homology to known lipases, Drosophila melanogaster CG3488. To evaluate the biochemical role, recombinant ABHD2 was expressed in Saccharomyces cerevisiae using pYES2/CT vector and His-tag purified protein showed TAG lipase activity. Ester hydrolase activity was confirmed with pNP acetate, butyrate and palmitate substrates respectively. Further, the ABHD2 homology model was built and the modelled protein was analysed based on the RMSD and root mean square fluctuation (RMSF) of the 100 ns simulation trajectory. Docking the acetate, butyrate and palmitate ligands with the model confirmed covalent binding of ligands with the Ser207 of the GXSXG motif. The model was validated with a mutant ABHD2 developed with alanine in place of Ser207 and the docking studies revealed loss of interaction between selected ligands and the mutant protein active site. Based on the above results, human ABHD2 was identified as a novel TAG lipase and ester hydrolase.

α/β-Hydrolase domain-6 and saturated long chain monoacylglycerol regulate insulin secretion promoted by both fuel and non-fuel stimuli.

Objectiveα/β-Hydrolase domain-6 (ABHD6) is a newly identified monoacylglycerol (MAG) lipase. We recently reported that it negatively regulates glucose stimulated insulin secretion (GSIS) in the β cells by hydrolyzing lipolysis-derived MAG that acts as a metabolic coupling factor and signaling molecule via exocytotic regulator Munc13-1. Whether ABHD6 and MAG play a role in response to all classes of insulin secretagogues, in particular various fuel and non-fuel stimuli, is unknown.MethodsInsulin secretion in response to various classes of secretagogues, exogenous MAG and pharmacological agents was measured in islets of mice deficient in ABHD6 specifically in the β cell (BKO). Islet perifusion experiments and determinations of glucose and fatty acid metabolism, cytosolic Ca2+ and MAG species levels were carried out.ResultsDeletion of ABHD6 potentiated insulin secretion in response to the fuels glutamine plus leucine and α-ketoisocaproate and to the non-fuel stimuli glucagon-like peptide 1, carbamylcholine and elevated KCl. Fatty acids amplified GSIS in control and BKO mice to the same extent. Exogenous 1-MAG amplified insulin secretion in response to fuel and non-fuel stimuli. MAG hydrolysis activity was greatly reduced in BKO islets without changes in total diacylglycerol and triacylglycerol lipase activity. ABHD6 deletion induced insulin secretion independently from KATP channels and did not alter the glucose induced rise in intracellular Ca2+. Perifusion studies showed elevated insulin secretion during second phase of GSIS in BKO islets that was not due to altered cytosolic Ca2+ signaling or because of changes in glucose and fatty acid metabolism. Glucose increased islet saturated long chain 1-MAG species and ABHD6 deletion caused accumulation of these 1-MAG species at both low and elevated glucose.ConclusionABHD6 regulates insulin secretion in response to fuel stimuli at large and some non-fuel stimuli by controlling long chain saturated 1-MAG levels that synergize with other signaling pathways for secretion.

Conjugated linoleic acid alters growth performance, tissue lipid deposition, and fatty acid composition of darkbarbel catfish (Pelteobagrus vachelli).

Fatty liver syndrome is a prevalent problem of farmed fish. Conjugated linoleic acid (CLA) has received increased attention recently as a fat-reducing fatty acid to control fat deposition in mammals. Therefore, the aim of the present study was to determine whether dietary CLA can reduce tissue lipid content of darkbarbel catfish (Pelteobagrus vachelli) and whether decreased lipid content is partially due to alterations in lipid metabolism enzyme activities and fatty acid profiles. A 76-day feeding trial was conducted to investigate the effect of dietary CLA on the growth, tissue lipid deposition, and fatty acid composition of darkbarbel catfish. Five diets containing 0 % (control), 0.5 % (CLA0.5), 1 % (CLA1), 2 % (CLA2), and 3 % (CLA3) CLA levels were evaluated. Results showed that fish fed with 2-3 % CLA diets showed a significantly lower specific growth rate and feed conversion efficiency than those fed with the control diet. Dietary CLA decreased the lipid contents in the liver and intraperitoneal fat with the CLA levels from 1 to 3 %. Fish fed with 2-3 % CLA diets showed significantly higher lipoprotein lipase and hepatic triacylglycerol lipase activities in liver than those of fish fed with the control, and fish fed with 1-3 % CLA diets had significantly higher pancreatic triacylglycerol lipase activities in liver than those of fish fed with the control. Dietary CLA was incorporated into liver, intraperitoneal fat, and muscle lipids, with higher percentages observed in liver compared with other tissues. Liver CLA deposition was at the expense of monounsaturated fatty acids (MUFA). In contrast, CLA deposition appeared to be primarily at the expense of MUFA and n-3 polyunsaturated fatty acids (PUFA) in the intraperitoneal fat, whereas in muscle it was at the expense of n-3 PUFA. Our results suggested that CLA at a 1 % dose can reduce liver lipid content without eliciting any negative effect on growth rate in darkbarbel catfish. This lipid-lowering effect could be in part due to an increment in the activity of lipid metabolism enzymes and an extensive interconversion of fatty acids. Although CLA deposition in muscle (0.66-3.19 % of total fatty acids) are higher than presented in natural sources of CLA, EPA (C20:5n-3) in fish muscle appears simultaneously expendable, when the fish fed with 2-3 % CLA.

Metabolic profiling reveals that PNPLA3 induces widespread effects on metabolism beyond triacylglycerol remodeling in Huh-7 hepatoma cells.

PNPLA3 was recently associated with the susceptibility to nonalcoholic fatty liver disease, a common cause of chronic liver disease characterized by abnormal triglyceride accumulation. Although it is established that PNPLA3 has both triacylglycerol lipase and acylglycerol O-acyltransferase activities, is still unknown whether the gene has any additional role in the modulation of the human liver metabolome. To uncover the functional role of PNPLA3 on liver metabolism, we performed high-throughput metabolic profiling of PNPLA3 siRNA-silencing and overexpression of wild-type and mutant Ile148Met variants (isoleucine/methionine substitution at codon 148) in Huh-7 cells. Metabolomic analysis was performed by using GC/MS and LC/MS platforms. Silencing of PNPLA3 was associated with a global perturbation of Huh-7 hepatoma cells that resembled a catabolic response associated with protein breakdown. A significant decrease in amino- and γ-glutamyl-amino acids and dipeptides and a significant increase in cysteine sulfinic acid, myo-inositol, lysolipids, sphingolipids, and polyunsaturated fatty acids were observed. Overexpression of the PNPLA3 Met148 variant mirrored many of the metabolic changes observed during gene silencing, but in the opposite direction. These findings were replicated by the exploration of canonical pathways associated with PNPLA3 silencing and Met148 overexpression. Overexpression of the PNPLA3 Met148 variant was associated with a 1.75-fold increase in lactic acid, suggesting a shift to anaerobic metabolism and mitochondrial dysfunction. Together, these results suggest a critical role of PNPLA3 in the modulation of liver metabolism beyond its classical participation in triacylglycerol remodeling.

Olive seed protein bodies store degrading enzymes involved in mobilization of oil bodies.

The major seed storage reserves in oilseeds are accumulated in protein bodies and oil bodies, and serve as an energy, carbon, and nitrogen source during germination. Here, the spatio-temporal relationships between protein bodies and several key enzymes (phospholipase A, lipase, and lipoxygenase) involved in storage lipid mobilization in cotyledon cells was analysed during in vitro seed germination. Enzyme activities were assayed in-gel and their cellular localization were determined using microscopy techniques. At seed maturity, phospholipase A and triacylglycerol lipase activities were found exclusively in protein bodies. However, after seed imbibition, these activities were shifted to the cytoplasm and the surface of the oil bodies. The activity of neutral lipases was detected by using α-naphthyl palmitate and it was associated mainly with protein bodies during the whole course of germination. This pattern of distribution was highly similar to the localization of neutral lipids, which progressively appeared in protein bodies. Lipoxygenase activity was found in both the protein bodies and on the surface of the oil bodies during the initial phase of seed germination. The association of lipoxygenase with oil bodies was temporally correlated with the appearance of phospholipase A and lipase activities on the surface of oil bodies. It is concluded that protein bodies not only serve as simple storage structures, but are also dynamic and multifunctional organelles directly involved in storage lipid mobilization during olive seed germination.

Olive oil improves the intestinal absorption and bioavailability of lutein in lutein-deficient mice

To investigate the influence of olive (OO), groundnut (GNO), soybean (SBO), sunflower (SFO), rice bran (RBO), corn (CO), palm (PO) oil or mixed micelle (control) on absorption kinetics and bioavailability of lutein in lutein-deficient mice. Additional aim was to correlate the activity of intestinal triacylglycerol lipase with intestinal and plasma lutein levels. After induction of lutein deficiency, mice (n = 165) were divided into eight groups (OO, SFO, GNO, RBO, PO, CO, SBO and control; n = 20/group) and the remaining (n = 5) were used as baseline (0 h). Groups were further divided into four subgroups (n = 5/subgroup) and were intubated with lutein (200 μM) dispersed in different vegetable oils. Plasma and tissue (intestine, liver and eyes), lutein, triglycerides, intestinal triacylglycerol lipases and fatty acid profile of plasma and tissues were measured at different time intervals. The percentage area under the curve value for plasma lutein in OO and GNO was higher by 41.8 and 5.1 %, while it was lower in other groups (18.2-53.3 %), when compared to control. Similarly, the percentage area under the curve for eye lutein in OO and GNO groups was higher by 35.2 and 4.8 %, whereas in other groups it was lower (5.4-69 %) than in control. Results show that olive oil facilitates the lutein absorption more compared to other vegetable oils, which may be due to the difference in fatty acid composition and higher activity of intestinal triacylglycerol lipase. Dietary olive oil rich in oleic acid improves the bioavailability and accumulation of lutein in lutein-deficient mice by modifying the intestinal triacylglycerol lipase activity.

APOC3 and PNPLA3 in non‐alcoholic fatty liver disease: Need to clear the air

See article in J. Gastroenterol. Hepatol. 2012; 27: 951–956.

Crystal structure of the predicted phospholipase LYPLAL1 reveals unexpected functional plasticity despite close relationship to acyl protein thioesterases

Sequence homology indicates the existence of three human cytosolic acyl protein thioesterases, including APT1 that is known to depalmitoylate H- and N-Ras. One of them is the lysophospholipase-like 1 (LYPLAL1) protein that on the one hand is predicted to be closely related to APT1 but on the other hand might also function as a potential triacylglycerol lipase involved in obesity. However, its role remained unclear. The 1.7 Å crystal structure of LYPLAL1 reveals a fold very similar to APT1, as expected, but features a shape of the active site that precludes binding of long-chain substrates. Biochemical data demonstrate that LYPLAL1 exhibits neither phospholipase nor triacylglycerol lipase activity, but rather accepts short-chain substrates. Furthermore, extensive screening efforts using chemical array technique revealed a first small molecule inhibitor of LYPLAL1.