Understanding structural features of microbial lipases--an overview

Biochemical study and digestion profile of olive oil by LipBK: Revealing the potential applications of a new acid/broad thermal range true lipase

This study characterized a novel bacterial lipase with high biotechnological potential, focusing on industrial and environmental applications. Bacterial isolates were screened using olive oil as a substrate, and the strain with the highest hydrolytic halo was identified as Burkholderia sp. via 16S rRNA analysis. The secreted lipase was purified and exhibited high hydrolytic activity, specifically targeting long-chain fatty acids. Gas chromatography analyses confirmed its ability to hydrolyze fatty acids present in olive oil, while kinetic parameters and substrate preferences were assessed using synthetic substrates. Optimal activity was observed at pH 4.5 and temperatures between 40 and 60 °C. The enzyme demonstrated remarkable thermal stability, retaining over 78 % residual activity after 24 h at 30, 40, 60, and even 70 °C. It also displayed broad pH stability, with increased relative activity at pH 6.5 over time. LipBK showed resilience in the presence of metallic ions, salts, EDTA, and non-ionic detergents, with enhanced activity in the presence of additives like KCl, CaCl₂, and Triton X-100. These properties highlight its robustness and suitability for applications in acidic and thermally variable environments, such as biodiesel production, waste treatment, and sustainable industrial processes, contributing to global sustainability goals.

Use of genomics & proteomics in studying lipase producing microorganisms & its application

In biotechnological applications, lipases are recognized as the most widely utilized and versatile enzymes, pivotal in biocatalytic processes, predominantly produced by various microbial species. Utilizing omics technology, natural sources can be meticulously screened to find microbial flora which are responsible for oil production. Lipases are versatile biocatalysts. They are used in a variety of bioconversion reactions and are receiving a lot of attention because of the quick development of enzyme technology and its usefulness in industrial operations. This article offers recent insights into microbial lipase sources, including fungi, bacteria, and yeast, alongside traditional and modern methods of purification such as precipitation, immunopurification and chromatographic separation. Additionally, it explores innovative methods like the reversed micellar system, aqueous two-phase system (ATPS), and aqueous two-phase flotation (ATPF). The article deals with the use of microbial lipases in a variety of sectors, including the food, textile, leather, cosmetics, paper, detergent, while also critically analyzing lipase-producing microbes. Moreover, it highlights the role of lipases in biosensors, biodiesel production, tea processing, bioremediation, and racemization. This review provides the concept of the use of omics technique in the mechanism of screening of microbial species those are capable of producing lipase and also find the potential applications.

Thiol-selective native grafting from polymerization for the generation of protein-polymer conjugates

Protein-polymer conjugates combine properties of biopolymers and synthetic polymers, such as specific bioactivity and increased stability, with great benefits for various applications from catalysis to biomedicine. Furthermore, polymer conjugation can mimic important posttranslational modifications of proteins such as glycosylation. There are typically two approaches to create protein-polymer conjugates: the protein is functionalized in advance with an initiator for a grafting-from method or a previously produced polymer is conjugated to the protein via a grafting-to method. In this study, we present a new approach that uses native proteins and allows for direct grafting-from using a thiol-induced, light-activated controlled radical polymerization (TIRP) that is initiated at thiols from specific cysteine residues of the protein. This straightforward method is employed to introduce polymers onto proteins and enzymes without any prior protein modifications, it works in aqueous buffer and maintains the protein's native structure and activity. The resulting protein-polymer conjugates exhibit high molar masses and low dispersities. We demonstrate the versatility of this approach by introducing different types of polymers such as hydrophilic poly(2-hydroxyethyl acrylate) (pHEAA), temperature-responsive poly(N-isopropylacrylamide) (pNIPAM) as well as glycopolymers mimicking the natural protein glycosylation and enabling selective interactions. We present successful combinations of the protein and polymer functions e.g., temperature-induced aggregation leading to an increase in enzyme activity and the introduction of artificial glycosylation inducing specific protein-protein cluster formation and giving straightforward access to glycosurfaces. Based on this straightforward, potentially scalable yet highly controlled synthesis of protein-polymer conjugates, various areas of applications are envisioned ranging from biomedicine to material sciences.

Ultrasensitive Nanofiber Biosensor: Rapid In Situ Chromatic Detection of Bacteria for Healthcare Innovation

Rapid detection of bacterial presence in skin wounds is crucial to prevent the transition from acute to chronic wounds and the onset of systemic infections. Current methods for detecting infections, particularly at low concentrations (<1.0 × 105 CFU/cm2), often require complex technologies and direct sampling, which can be invasive and time-consuming. Addressing this gap, we introduce a colorimetric nanofibrous biosensor enabling real-time in situ monitoring of bacterial concentrations in wounds. This biosensor employs a colorimetric hemicyanine dye (HCy) probe, which changes color in response to bacterial lipase, a common secretion in infected wounds. To enhance the biosensor's sensitivity, we incorporated two key materials science strategies: aligning the nanofibers to promote efficient bacterial attachment and localization and integrating Tween 80, a surfactant, within the nanofiber matrix. This combination of physical and chemical cues results in a notable increase in lipase activity. The cross-aligned core-shell nanofibers, embedded with Tween 80 and HCy, demonstrate an immediate and distinct color change when exposed to as low as 3.0 × 104 CFU/cm2 of common pathogens such as Pseudomonas aeruginosa and MRSA. Significantly, the presence of Tween 80 amplifies the colorimetric response, making visual detection more straightforward and four times more pronounced. Our nanobiosensor design facilitates the detection of low-concentration bacterial infections in situ without the need to remove wound dressings. This advancement marks a significant step forward in real-time wound monitoring, offering a practical tool for the early detection of clinical bacterial infections.

Artificial Intelligence Aided Lipase Production and Engineering for Enzymatic Performance Improvement

With the development of artificial intelligence (AI), tailoring methods for enzyme engineering have been widely expanded. Additional protocols based on optimized network models have been used to predict and optimize lipase production as well as properties, namely, catalytic activity, stability, and substrate specificity. Here, different network models and algorithms for the prediction and reforming of lipase, focusing on its modification methods and cases based on AI, are reviewed in terms of both their advantages and disadvantages. Different neural networks coupled with various algorithms are usually applied to predict the maximum yield of lipase by optimizing the external cultivations for lipase production, while one part is used to predict the molecule variations affecting the properties of lipase. However, few studies have directly utilized AI to engineer lipase by affecting the structure of the enzyme, and a set of research gaps needs to be explored. Additionally, future perspectives of AI application in enzymes, including lipase engineering, are deduced to help the redesign of enzymes and the reform of new functional biocatalysts. This review provides a new horizon for developing effective and innovative AI tools for lipase production and engineering and facilitating lipase applications in the food industry and biomass conversion.

Comprehensive sequence and structure analysis of algal lipid catabolic enzyme Triacylglycerol lipase: an in silico study to vitalize the development of optimum engineered strains with high lipid productivity

Microalgae as an alternative renewable resource for biofuel production have captured much significance. Nonetheless, its economic viability is a field of major concern for researchers. Unraveling the lipid catabolic pathway and gaining insights into the sequence-structural features of its primary functioning enzyme, Triacylglycerol lipase, will impart valuable information to target microalgae for augmented lipid content. In the present study, a genome-wide comparative study on putative Triacylglycerol lipase (TAGL) enzyme from algal species belonging to varied phylogenetic lineages was performed. The comprehensive sequence analysis revealed that TAGL comprises of three distinct conserved domains, such as, Patatin, Class III Lipase, and Abhydro_lipase, and also confirmed the ubiquitous presence of GXSXG motif in the sequences analyzed. In the absence of a crystal structure of algal TAGL till date, we developed the first 3D model of patatin domain of TAGL from an oleaginous microalga, Phaedactylum tricornutum, employing homology modeling, docking and molecular dynamic simulations methods. The domain-substrate complex having the low-ranking docking score revealed the binding of palmitic acid to the TAGL patatin domain surface with strong hydrogen bond interactions. The simulation results implied that the substrate-complexed patatin domain and the free enzyme adopted a more stable conformation after 40 ns. This is the first ever attempt to provide in-silico insights into the structural and dynamical insights on catalytic mechanism of the TAGL patatin domain. Subsequently, these findings aided our understanding on their structural stability, folding mechanism and protein-substrate interactions, which could be further utilized to design site-specific mutagenic experiments for engineering microalgal strains.Communicated by Ramaswamy H. Sarma.

Bioinformatic characterization of a triacylglycerol lipase produced by Aspergillus flavus isolated from the decaying seed of Cucumeropsis mannii

Lipases are enzymes of industrial importance responsible for the hydrolysis of ester bonds of triglycerides. A lipolytic fungus was isolated and subsequently identified based on the ITS sequence analysis as putative Aspergillus flavus with accession number LC424503. The gene coding for extracellular triacylglycerol lipase was isolated from Aspergillus flavus species, sequenced, and characterised using bioinformatics tools. An open reading frame of 420 amino acid sequence was obtained and designated as Aspergillus flavus lipase (AFL) sequence. Alignment of the amino acid sequence with other lipases revealed the presence GHSLG sequence which is the lipase consensus sequence Gly-X1-Ser-X2-Gly indicating that it a classical lipase. A catalytic active site lid domain composed of TYITDTIIDLS amino acids sequence was also revealed. This lid protects the active site, control the catalytic activity and substrate selectivity in lipases. The 3-Dimensional structural model shared 34.08% sequence identity with a lipase from Yarrowia lipolytica covering 272 amino acid residues of the template model. A search of the lipase engineering database using AFL sequence revealed that it belongs to the class GX-lipase, superfamily abH23 and homologous family abH23.02, molecular weight and isoelectric point values of 46.95 KDa and 5.7, respectively. N-glycosylation sites were predicted at residues 164, 236 and 333, with potentials of 0.7250, 0.7037 and 0.7048, respectively. O-glycosylation sites were predicted at residues 355, 358, 360 and 366. A signal sequence of 37 amino acids was revealed at the N-terminal of the polypeptide. This is a short peptide sequence that marks a protein for transport across the cell membrane and indicates that AFL is an extracellular lipase. The findings on the structural and molecular properties of Aspergillus flavus lipase in this work will be crucial in future studies aiming at engineering the enzyme for biotechnology applications.Communicated by Ramaswamy H. Sarma.

Utilization of Clay Materials as Support for Aspergillus japonicus Lipase: An Eco-Friendly Approach

Lipase is an important group of biocatalysts, which combines versatility and specificity, and can catalyze several reactions when applied in a high amount of industrial processes. In this study, the lipase produced by Aspergillus japonicus under submerged cultivation, was immobilized by physical adsorption, using clay supports, namely, diatomite, vermiculite, montmorillonite KSF (MKSF) and kaolinite. Besides, the immobilized and free enzyme was characterized, regarding pH, temperature and kinetic parameters. The most promising clay support was MKSF that presented 69.47% immobilization yield and hydrolytic activity higher than the other conditions studied (270.7 U g−1). The derivative produced with MKSF showed high stability at pH and temperature, keeping 100% of its activity throughout 12 h of incubation in the pH ranges between 4.0 and 9.0 and at a temperature from 30 to 50 °C. In addition, the immobilized lipase on MKSF support showed an improvement in the catalytic performance. The study shows the potential of using clays as support to immobilized lipolytic enzymes by adsorption method, which is a simple and cost-effective process.

Metaproteomic Discovery and Characterization of a Novel Lipolytic Enzyme From an Indian Hot Spring

Lipolytic enzymes are produced by animals, plants and microorganisms. With their chemo-, regio-, and enantio-specific characteristics, lipolytic enzymes are important biocatalysts useful in several industrial applications. They are widely used in the processing of fats and oils, detergents, food processing, paper and cosmetics production. In this work, we used a new functional metaproteomics approach to screen sediment samples of the Indian Bakreshwar hot spring for novel thermo- and solvent-stable lipolytic enzymes. We were able to identify an enzyme showing favorable characteristics. DS-007 showed high hydrolytic activity with substrates with shorter chain length (C10, significantly less hydrolytic activity was observed. A preference for short chain acyl groups is characteristic for esterases, suggesting that DS-007 is an esterase. Consistent with the high temperature at its site of isolation, DS-007 showed a temperature optimum at 55°C and retained 80% activity even after prolonged exposure to temperatures as high as 60°C. The enzyme showed optimum activity at pH 9.5, with more than 50% of its optimum activity between pH 8.0 and pH 9.5. DS-007 also exhibited tolerance toward organic solvents at a concentration of 1% (v/v). One percent of methanol increased the activity of DS-007 by 40% in comparison to the optimum conditions without solvent. In the presence of 10% methanol, DMSO or isopropanol DS-007 still showed around 50% activity. This data indicates that DS-007 is a temperature- and solvent-stable thermophilic enzyme with reasonable activity even at lower temperatures as well as a catalyst that can be used at a broad range of pH values with an optimum in the alkaline range, showing the adaptation to the habitat's temperature and alkaline pH.

Microbial lipase production: A deep insight into the recent advances of lipase production and purification techniques

Importance of enzymes is ever-rising particularly microbial lipases holding great industrial worth owing to their potential to catalyze a diverse array of chemical reactions in aqueous as well as nonaqueous settings. International lipase market is anticipated to cross USD 797.7 million till 2025, rising at a 6.2% compound annual growth rate from 2017 to 2025. The recent breakthrough in the field of lipase research is the generation of new and upgraded versions of lipases via molecular strategies. For example, integration of rational enzyme design and directed enzyme evolution to attain desired properties in lipases. Normally, purification of lipase with significant purity is achieved through a multistep procedure. Such multiple step approach of lipase purification entails both conventional and novel techniques. The present review attempts to provide an overview of different aspects of lipase production including fermentation techniques, factors affecting lipase production, and purification strategies, with the aim to assist researchers to pick a suitable technique for the production and purification of lipase.

Advances in Recombinant Lipases: Production, Engineering, Immobilization and Application in the Pharmaceutical Industry

Lipases are one of the most used enzymes in the pharmaceutical industry due to their efficiency in organic syntheses, mainly in the production of enantiopure drugs. From an industrial viewpoint, the selection of an efficient expression system and host for recombinant lipase production is highly important. The most used hosts are Escherichia coli and Komagataella phaffii (previously known as Pichia pastoris) and less often reported Bacillus and Aspergillus strains. The use of efficient expression systems to overproduce homologous or heterologous lipases often require the use of strong promoters and the co-expression of chaperones. Protein engineering techniques, including rational design and directed evolution, are the most reported strategies for improving lipase characteristics. Additionally, lipases can be immobilized in different supports that enable improved properties and enzyme reuse. Here, we review approaches for strain and protein engineering, immobilization and the application of lipases in the pharmaceutical industry.

Low-resolution molecular shape, biochemical characterization and emulsification properties of a halotolerant esterase from Bacillus licheniformis

Bacterial esterases are highly versatile enzymes, currently widely used in detergents, biosurfactants, bioemulsifiers and as biocatalysts in paper and food industries. Present work describes heterologous expression, purification, and biophysical and biochemical characterization of a halotolerant esterase from Bacillus licheniformis (BlEstA). BlEstA preferentially cleaves pNP-octanoate and both activity and stability of the enzyme increased in the presence of 2 M NaCl, and also with several organic solvents (ethanol, methanol and DMSO). Furthermore, BlEstA has considerable emulsifying properties, particularly with olive oil as substrate. Our studies also show that the enzyme is monomeric in solution and its small-angle X-ray scattering low-resolution molecular envelope fits well its high-resolution homology model.

Enzymatic reactions in the production of biomethane from organic waste

Enzymatic reactions refer to organic reactions catalyzed by enzymes. This review aims to enrich the documentation relative to enzymatic reactions occurring during the anaerobic degradation of residual organic substances with emphasis on the structures of organic compounds and reaction mechanisms. This allows to understand the displacement of electrons between electron-rich and electron-poor entities to form new bonds in products. The detailed mechanisms of enzymatic reactions relative to the production of biomethane have not yet been reviewed in the scientific literature. Hence, this review is novel and timely since it discusses the chemical behavior or reactivity of different functional groups, thereby allowing to better understand the enzymatic catalysis in the transformations of residual proteins, carbohydrates, and lipids into biomethane and fertilizers. Such understanding allows to improve the overall biomethanation efficiency in industrial applications.

Surface-Displayed Thermostable Candida rugosa Lipase 1 for Docosahexaenoic Acid Enrichment

Yeast surface display has emerged as a viable approach for self-immobilization enzyme as whole-cell catalysts. Herein, we displayed Candida rugosa lipase 1 (CRL LIP1) on the cell wall of Pichia pastoris for docosahexaenoic acid (DHA) enrichment in algae oil. After a 96-h culture, the displayed CRL LIP1 achieved the highest activity (380 ± 2.8 U/g) for hydrolyzing olive oil under optimal pH (7.5) and temperature (45 °C) conditions. Additionally, we improved the thermal stability of displayed LIP1, enabling retention of 50% of its initial bioactivity following 6 h of incubation at 45 °C. Furthermore, the content of DHA enhanced from 40.61% in original algae oil to 50.44% in glyceride, resulting in a 1.24-fold increase in yield. The displayed CRL LIP1 exhibited an improved thermal stability and a high degree of bioactivity toward its native macromolecule substrates algae oil and olive oil, thereby expanding its potential for industrial applications in fields of food and pharmaceutical. These results suggested that surface display provides an effective strategy for simultaneous convenient expression and target protein immobilization.

Characterization of ML-005, a Novel Metaproteomics-Derived Esterase

A novel gene encoding for a lipolytic enzyme, designated ML-005, was recently identified using a functional metaproteomics approach. We heterologously expressed this protein in Escherichia coli and biochemically characterized it. ML-005 exhibited lipolytic activity toward short-chained substrates with the preferred substrate being p-nitrophenyl-butyrate, suggesting that ML-005 is an esterase. According to homology analysis and site-directed mutagenesis, the catalytic triad of the enzyme was identified as Ser-99, Asp-164, and His-191. Its optimal pH was determined to be at pH 8. Optimal activity was observed at 45°C. It also exhibited temperature, pH and salt tolerance. Residual relative activity after incubating at 50–60°C for 360 min was above 80% of its initial activity. It showed tolerance over a broad range of pH (5–12) and retained most of its initial activity. Furthermore, incubating ML-005 in 1 – 5M NaCl solution had negligible effect on its activity. DTT, EDTA, and ß-mercaptoethanol had no significant effect on ML-005’s activity. However, addition of PMSF led to almost complete inactivation consistent with ML-005 being a serine hydrolase. ML-005 remains stable in the presence of a range of metal ions, but addition of Cu²⁺ significantly reduces its relative activity. Organic solvents have an inhibitory effect on ML-005, but it retained 21% of activity in 10% methanol. SDS had the most pronounced inhibitory effect on ML-005 among all detergents tested and completely inactivated it. Furthermore, the V_max of ML-005 was determined to be 59.8 μM/min along with a K_m of 137.9 μM. The k_cat of ML-005 is 26 s^-1 and k_cat/K_m is 1.88 × 10⁵ M^-1 s^-1.

Evolution of the diacylglycerol lipases

Diacylglycerol lipases (DGLs) mainly catalyze "on-demand" biosynthesis of bioactive monoacylglycerols (MAGs) with different long fatty acyl chains, including 2-arachidonoylglycerol (2-AG), 2-linoleoylglycerol (2-LG), 2-oleoylglycerol (2-OG) and 2-palmitoylglycerol (2-PG). Enzymatic characterization of DGLs, their expression and distribution, and functional features has been elucidated from microorganisms to mammals in some extent. In mammals, biosynthesis, degradation and metabolism of these bioactive lipids intertwine and form a complicated biochemical pathway to affect the mammal neuromodulation of central nervous system and also other physiological processes in most peripheral organs and non-nervous tissue cells, and yet we still do not know if the neuromodulatory role of mammal DGL and MAGs is similar to invertebrates. Tracing the evolutionary history of DGLs from microorganisms to vertebrates will be an essential method to infer DGL and MAG research in organisms. In this review, we give an exhaustive explanation of the ancestral origin, divergence and evolutionary pattern through systemic searching of DGL orthologs in different species. Finally, we also summarize our recent work on the structural and functional studies of DGL in order to explore usage of DGLs in industry and the development of inhibitors for clinical intervention.

Specific Inter-residue Interactions as Determinants of Human Monoacylglycerol Lipase Catalytic Competency: A ROLE FOR GLOBAL CONFORMATIONAL CHANGES

The serine hydrolase monoacylglycerol lipase (MGL) functions as the main metabolizing enzyme of 2-arachidonoyl glycerol, an endocannabinoid signaling lipid whose elevation through genetic or pharmacological MGL ablation exerts therapeutic effects in various preclinical disease models. To inform structure-based MGL inhibitor design, we report the direct NMR detection of a reversible equilibrium between active and inactive states of human MGL (hMGL) that is slow on the NMR time scale and can be modulated in a controlled manner by pH, temperature, and select point mutations. Kinetic measurements revealed that hMGL substrate turnover is rate-limited across this equilibrium. We identify a network of aromatic interactions and hydrogen bonds that regulates hMGL active-inactive state interconversion. The data highlight specific inter-residue interactions within hMGL modulating the enzymes function and implicate transitions between active (open) and inactive (closed) states of the hMGL lid domain in controlling substrate access to the enzymes active site.

A combined bioinformatics and functional metagenomics approach to discovering lipolytic biocatalysts

The majority of protein sequence data published today is of metagenomic origin. However, our ability to assign functions to these sequences is often hampered by our general inability to cultivate the larger part of microbial species and the sheer amount of sequence data generated in these projects. Here we present a combination of bioinformatics, synthetic biology, and Escherichia coli genetics to discover biocatalysts in metagenomic datasets. We created a subset of the Global Ocean Sampling dataset, the largest metagenomic project published to date, by removing all proteins that matched Hidden Markov Models of known protein families from PFAM and TIGRFAM with high confidence (E-value > 10^-5). This essentially left us with proteins with low or no homology to known protein families, still encompassing ~1.7 million different sequences. In this subset, we then identified protein families de novo with a Markov clustering algorithm. For each protein family, we defined a single representative based on its phylogenetic relationship to all other members in that family. This reduced the dataset to ~17,000 representatives of protein families with more than 10 members. Based on conserved regions typical for lipases and esterases, we selected a representative gene from a family of 27 members for synthesis. This protein, when expressed in E. coli, showed lipolytic activity toward para-nitrophenyl (pNP) esters. The K_m-value of the enzyme was 66.68 μM for pNP-butyrate and 68.08 μM for pNP-palmitate with k_cat/K_m values at 3.4 × 10⁶ and 6.6 × 10⁵ M^-1s^-1, respectively. Hydrolysis of model substrates showed enantiopreference for the R-form. Reactions yielded 43 and 61% enantiomeric excess of products with ibuprofen methyl ester and 2-phenylpropanoic acid ethyl ester, respectively. The enzyme retains 50% of its maximum activity at temperatures as low as 10°C, its activity is enhanced in artificial seawater and buffers with higher salt concentrations with an optimum osmolarity of 3,890 mosmol/l.

A gene encoding a new cold-active lipase from an Antarctic isolate of Penicillium expansum

Cold-active lipases are of significant interest as biocatalysts in industrial processes. We have identified a lipase that displayed activity towards long carbon-chain-p-nitrophenyl substrates (C12-C18) at 25 °C from the culture supernatant of an Antarctic Penicillium expansum strain assigned P. expansum SM3. Zymography revealed a protein band of around 30 kDa with activity towards olive oil. DNA fragments of a lipase gene designated as lipPE were isolated from the genomic DNA of P. expansum SM3 by genomic walking PCR. Subsequently, the complete genomic lipPE gene was amplified using gene-specific primers designed from the 5'- and 3'-regions. Reverse transcription PCR was used to amplify the lipPE cDNA. The deduced amino acid sequence consisted of 285 residues that included a predicted signal peptide. Three peptides identified by LC/MS/MS analysis of the proteins in the culture supernatant of P. expansum were also present in the deduced amino acid sequence of the lipPE gene suggesting that this gene encoded the lipase identified by initial zymogram activity analysis. Full analysis of the nucleotide and the deduced amino acid sequences indicated that the lipPE gene encodes a novel P. expansum lipase. The lipPE gene was expressed in E. coli for further characterization of the enzyme with a view of assessing its suitability for industrial applications.

Crystal structure of a mono- and diacylglycerol lipase from Malassezia globosa reveals a novel lid conformation and insights into the substrate specificity

Most lipases contain a lid domain to shield the hydrophobic binding site from the water environment. The lid, mostly in helical form, can undergo a conformational change to expose the active cleft during the interfacial activation. Here we report the crystal structures of Malassezia globosa LIP1 (SMG1) at 1.45 and 2.60 Å resolution in two crystal forms. The structures present SMG1 in its closed form, with a novel lid in loop conformation. SMG1 is one of the few members in the fungal lipase family that has been found to be strictly specific for mono- and diacylglycerol. To date, the mechanism for this substrate specificity remains largely unknown. To investigate the substrate binding properties, we built a model of SMG1 in open conformation. Based on this model, we found that the two bulky hydrophobic residues adjacent to the catalytic site and the N-terminal hinge region of the lid both may act as steric hindrances for triacylglycerols binding. These unique structural features of SMG1 will provide a better understanding on the substrate specificity of mono- and diacylglycerol lipases and a platform for further functional study of this enzyme.

Enzyme replacement therapy for pancreatic insufficiency: present and future

Pancreatic enzyme replacement therapy is currently the mainstay of treatment for nutrient malabsorption secondary to pancreatic insufficiency. This treatment is safe and has few side effects. Data demonstrate efficacy in reducing steatorrhea and fat malabsorption. Effective therapy has been limited by the ability to replicate the physiologic process of enzyme delivery to the appropriate site, in general the duodenum, at the appropriate time. The challenges include enzyme destruction in the stomach, lack of adequate mixing with the chyme in the duodenum, and failing to deliver and activate at the appropriate time. Treatment is begun when clinically significant malabsorption occurs resulting in steatorrhea and weight loss. Treatment failure is addressed in a sequential fashion. Current research is aimed at studying new enzymes and delivery systems to improve the efficiency of action in the duodenum along with developing better means to monitor therapy.