Purification and biochemical characterization of pancreatic phospholipase A2 from the common stingray Dasyatis pastinaca

Effective Soybean Oil Degumming by Immobilized Phospholipases A2 from Walterinnesia aegyptia Venom

Enzymatic degumming utilizing phospholipase enzymes could be used in ecologically friendly procedures with enhanced oil recovery yields. In this study, two phospholipases A2 of group I and II, WaPLA2-I and WaPLA2-II, from the snake venom of Saudi Walterinnesia aegyptia were evaluated for soybean oil degumming after being immobilized on three different support materials (calcium alginate (CA), CA-gelatin (CAG), and CA-chitosan (CAC), and cross-linked with glutaraldehyde). Higher yields of CAC-immobilized PLA2-I (85 ± 3%) and PLA2-II (87 ± 3.6%) compared to CAG (77.3 ± 2.1 and 79 ± 2.6%, respectively) and CA beads (55.7 ± 2.5% and 57.3 ± 3.1%, respectively) were observed. In addition, the optimal temperature of immobilized WaPLA2-I and WaPLA2-II increased from 45 to 55 °C and from 55 to 65 °C, respectively. Their stability at high temperatures was also significantly enhanced covering a larger range (70-80 °C). Likewise, the pH/activity profile of WaPLA2 was greatly expanded upon immobilization with the pH-optima being shifted by 0.5 to 1 pH unit to the basic side. Similarly, the stability of WaPLA2s in the presence of organic solvents was also significantly improved, while the affinity for calcium and bile salt was the same for both free and immobilized enzymes. Interestingly, the remaining activity of immobilized WaPLA2 onto different supports was more than 50 or 60% after eight recycles or 120 days of storage at 4 °C, respectively. CAC-WaPLA2-II was the best immobilized enzyme complex for the oil degumming process by reducing its final residual phosphorus content from 168 mg/kg to less than 10 mg/kg in only 4 h. Overall, CAC-WaPLA2-II showed the most attractive profiles of temperature, pH, and reaction duration as well as significant storage stability and reusability.

Development of aqueous two-phase systems-based approaches for the selective recovery of metalloproteases and phospholipases A2 toxins from Crotalus molossus nigrescens venom

Snake venoms are rich sources of proteins with potential biotechnological and pharmaceutical applications. Among them, metalloproteases (MPs) and phospholipases A2 (PLA2) are the most abundant. Their isolation involves a multistep chromatographic approach, which has proven to be effective, however implies high operating costs and long processing times. In this study, a cost-effective and simple method based on aqueous two-phase systems (ATPS) was developed to recover MPs and PLA2 from Crotalus molossus nigrescens venom. A system with PEG 400 g mol-1, volume ratio (VR) 1, tie line length (TLL) 25% w/w and pH 7 showed the best performance for PLA2 recovery. In systems with PEG 400 g mol-1, VR 1, TLL 15% w/w, pH 7 and 1 and 3% w/w of NaCl, selective recovery of MP subtype P-III was achieved; whereas, in a system with PEG 400 g mol-1, VR 1, TLL 25% w/w and pH 8.5, MP subtypes P-I and P-III were recovered. Due to their low costs, ethanol-salt systems were also evaluated, however, failed to differentially partition PLA2 and MPs. The use of ATPS could contribute to the simplification and cost reduction of protein isolation processes from snake venoms and other toxin fluids, as well as potentially aid their biochemical, proteomic and biological analyses.

Hematology and blood biochemistry profile of the freshwater stingray Potamotrygon magdalenae as a tool for population assessment in artificial environments

Hematological and blood biochemical reference information is important to establish physiological status of freshwater stingray populations and improve care and management protocols in artificial environments. Here, we used a commercial freshwater stingray with high mortality rates in the market (Potamotrygon magdalenae), as an example to understand how artificial environments and handling protocols influence physiological status of captive freshwater stingrays. To this purpose, blood from five adult males and six adult females was collected to perform complete blood counts and blood chemistry analyses. All sampled animals showed good body condition with no differences between sexes. Differences between sexes were only found for the differential count of lymphocytes. Red blood results were consistent with previously studied potamotrygonids while white blood results showed higher values of leukocytes, thrombocytes, heterophils and lymphocytes in P. magdalenae compared to other Potamotrygonids. All types of leukocytes described for elasmobranchs were found except neutrophils and basophils. Blood metabolites showed an influence of ex situ diet in total protein, triglycerides and cholesterol. Glucose results were consistent while urea showed lower levels than those recorded for other freshwater stingrays. These results highlight the importance of physical, physiological and health analysis in freshwater stingrays as a part of welfare assessment to improve monitoring protocols and survival rates in public or private aquaria.

Phospholipase A2 enzyme from the venom of Egyptian honey bee Apis mellifera lamarckii with anti-platelet aggregation and anti-coagulation activities

Background

Honey bee venom contains various enzymes with wide medical and pharmaceutical applications.

Results

The phospholipase A2 (PLA2) has been apparently purified from the venom of Egyptian honey bee (Apis mellifera lamarckii) 8.9-fold to a very high specific activity of 6033 U/mg protein using DEAE–cellulose and Sephacryl S-300 columns. The purified bee venom PLA2 is monomeric 16 kDa protein and has isoelectric point (pI) of 5.9. The optimal activity of bee venom PLA2 was attained at pH 8 and 45 °C. Cu²⁺_, Ni²⁺, Fe²⁺_, Ca²⁺, and Co²⁺ exhibited a complete activating effect on it, while Zn²⁺, Mn²⁺, NaN₃, PMSF, N-Methylmaleimide, and EDTA have inhibitory effect.

Conclusions

The purified bee venom PLA2 exhibited anti-platelet aggregation and anti-coagulation activities which makes it promising agent for developing novel anti-clot formation drugs in future.

Cytotoxic, Antioxidant, and Metabolic Enzyme Inhibitory Activities of Euphorbia cyparissias Extracts

Plants of the Euphorbia genus present a wide range of therapeutic applications. This study is aimed at investigating new antidigestive enzyme agents from Euphorbia cyparissias through inhibition of lipid and carbohydrate absorption, to evaluate their potential applications for the treatment of metabolic syndrome. Lipase, phospholipase, protease, α-amylase, β-glucosidase, and xanthine oxidase activities under treatment with aqueous and ethanolic extracts of Euphorbia cyparissias were observed to evaluate the inhibitory effect of these extracts, as well as their antioxidant and cytotoxic effects. Results showed that ethanolic and aqueous extracts exhibited important inhibitory activity in a concentration-related manner on digestive enzymes, which is more effective than the commercial drugs used as controls. Results also showed that, out of the two extracts tested, the ethanolic extract presented the most promising results in inhibiting the activities of all digestive enzymes used. Moreover, the two extracts displayed a higher reducing power than that of the positive control used. The obtained results, together with previous reports in the literature, strongly suggest that Euphorbia cyparissias extracts may be natural inhibitors of the digestive enzymes and thus a potential new drug for metabolic syndrome treatment.

A novel bactericidal homodimeric PLA2 group-I from Walterinnesia aegyptia venom

A novel non-toxic phospholipase A₂ was purified to homogeneity in a single chromatography step from the venom of Walterinnesia aegyptia, a monotypic elapid snake caught in Saudi Arabia, and its antimicrobial and hemolytic properties were evaluated as well. This enzyme, namely WaPLA₂, is a homodimer with an estimated molecular mass of 30 kDa, and its NH₂-terminal sequence exhibits a significant degree of similarity with PLA₂ group-I. At optimal pH (8.5) and temperature (45 °C), the purified PLA₂ exhibited a specific activity of 2100 U/mg, and it requires bile salts and Ca²⁺ for its activity. However, other cations such as Cd²⁺ and Hg²⁺ diminished the enzyme activity remarkably, thereby suggesting that the catalytic site arrangement has an exclusive structure for Ca²⁺ binding. Furthermore, WaPLA₂ maintained almost 100% and 60% of its full activity in a pH range of 6.0-10 after 24 h incubation or after 60 min treatment at 70 °C, respectively. In the biological activity assays, WaPLA₂ displayed potent indirectly hemolytic and antimicrobial activities that were strongly correlated. These promising findings encourage further in-depth research to understand the molecular mechanism of WaPLA₂'s antimicrobial properties for its possible use as a potential therapeutic lead molecule for treating infections.

Functional and Structural Characterization of a Thermostable Phospholipase A2 from a Sparidae Fish (Diplodus annularis)

Novel phospholipase (PLA₂) genes from the Sparidae family were cloned. The sequenced PLA₂ revealed an identity with pancreatic PLA₂ group IB. To better understand the structure/function relationships of these enzymes and their evolution, the Diplodus annularis PLA₂ (DaPLA₂) was overexpressed in E. coli. The refolded enzyme was purified by Ni-affinity chromatography and has a molecular mass of 15 kDa as determined by MALDI-TOF spectrometry. Interestingly, unlike the pancreatic type, the DaPLA₂ was active and stable at higher temperatures, which suggests its great potential in biotechnological applications. The 3D structure of DaPLA₂ was constructed to gain insights into the functional properties of sparidae PLA₂. Molecular docking and dynamic simulations were performed to explain the higher thermal stability and the substrate specificity of DaPLA₂. Using the monolayer technique, the purified DaPLA₂ was found to be active on various phospholipids ranging from 10 to 20 mN·m^-1, which explained the absence of the hemolytic activity for DaPLA₂.

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications

Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

Anti-bactericidal properties of stingray Dasyatis pastinaca groups V, IIA, and IB phospholipases A2: a comparative study

Group IIA secreted phospholipase A2 (group IIA sPLA2) is known to display potent Gram-positive bactericidal activity in vitro and in vivo. We have analyzed the bactericidal activity of the full set of native stingray and dromedary groups V, IIA, and IB sPLA2s on several Gram-positive and Gram-negative strains. The rank order potency among both marine and mammal sPLA2s against Gram-positive bacteria is group IIA > V > IB, whereas Gram-negative bacteria exhibited a much higher resistance. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2.The bactericidal efficiency of groups V and IIA sPLA2s was shown to be dependent upon the presence of calcium ions and to a less extent Mg(2+) ions and then a correlation could be made to its hydrolytic activity of membrane phospholipids. Importantly, we showed that stingray and dromedary groups V, IIA, and IB sPLA2s present no cytotoxicity after their incubation with MDA-MB-231cells. stingray groups V and IIA sPLA2s, like mammal ones, may be considered as future therapeutic agents against bacterial infections.

Enzymatic properties of stingray Dasyatis pastinaca group V, IIA and IB phospholipases A(2): a comparative study

In the present study, we have purified the group V phospholipase from the heart of cartilaginous fish stingray Dasyatis pastinaca and compared its biochemical properties with group IIA (sPLA2-IIA) and IB (sPLA2-IB) phospholipases previously purified from pancreas and intestine, respectively. Group V phospholipase (sPLA2-V) was purified to homogeneity by heat treatment, ammonium sulphate precipitation and RP-HPLC. The N-terminal sequence of the purified sPLA2-V exhibits a high degree of homology with those of mammal. The enzyme was found to be monomeric with a molecular mass estimation of 14 kDa. The specific activity of the purified enzyme, measured at pH 8 and 37 °C was 52 U/mg. Like sPLA2-IB and sPLA2-IIA, the sPLA2-V is found to be stable between pH 3 and 11 after 30 min of incubation. The purified sPLA2-V retained 65% of its activity after 10 min of incubation at 70 °C and it absolutely requires Ca(2+) for enzymatic activity. In addition it displayed high tolerance to organic solvents. Kinetic parameters Kmapp, kcat and the deduced catalytic efficiency (kcat/Kmapp) of the purified group-V, -IB and -IIA PLA2s were determined using phosphatidylethanolamine (PE), phosphatidylcholine (PC) or phosphatidylserine (PS) as substrate. The three enzymes hydrolyze the zwiterionic PE and PC substrates more efficiently than anionic PS substrate.

Antibacterial properties of intestinal phospholipase A2 from the common stingray Dasyatis pastinaca

Stingray phospholipase A(2) group IIA (SPLA(2)-IIA) was recently isolated and purified to homogeneity from the intestine of the common stingray Dasyatis pastinaca, suggesting that this enzyme plays an important role in systemic bactericidal defense. The present study showed that SPLA(2)-IIA was highly bactericidal against Gram-positive bacteria with inhibition zones and minimal inhibitory concentration values in the range of 13-25 mm and 2-8 μg/ml, respectively, whereas Gram-negative bacteria exhibited a much higher resistance. The bactericidal efficiency of SPLA(2)-IIA was shown to be unaffected by high protein and salt concentrations, but dependent upon the presence of calcium ions, and then correlated to the hydrolytic activity of membrane phospholipids. Importantly, we showed that stingray phospholipase A(2) group IIA presents no cytotoxicity after its incubation with MDA-MB-231 cells. SPLA(2)-IIA may be considered as a future therapeutic agent against bacterial infections.

Proteolytic cleavage of stingray phospholipase A2: isolation and biochemical characterization of an active N-terminal form

Background

Mammalian GIB-PLA2 are well characterized. In contrast, much less is known about aquatic ones. The aquatic world contains a wide variety of living species and, hence represents a great potential for discovering new lipolytic enzymes. The aim of this study was to check some biochemical and structural properties of a marine stingray phospholipase A2 (SPLA2).

Results

The effect of some proteolytic enzymes on SPLA2 was checked. Chymotrypsin and trypsin were able to hydrolyze SPLA2 in different ways. In both cases, only N-terminal fragments were accumulated during the hydrolysis, whereas no C-terminal fragment was obtained in either case. Tryptic and chymotryptic attack generated 13 kDa and 12 kDa forms of SPLA2, respectively. Interestingly, the SPLA2 13 kDa form was inactive, whereas the SPLA2 12 kDa form conserved almost its full phospholipase activity. In the absence of bile slats both native and 12kDa SPLA2 failed to catalyse the hydrolysis of PC emulsion. When bile salts were pre-incubated with the substrate, the native kinetic protein remained linear for more than 25 min, whereas the 12 kDa form activity was found to decrease rapidly. Furthermore, The SPLA2 activity was dependent on Ca²⁺; other cations (Mg²⁺, Mn²⁺, Cd²⁺ and Zn²⁺) reduced the enzymatic activity notably, suggesting that the arrangement of the catalytic site presents an exclusive structure for Ca²⁺.

Conclusions

Although marine and mammal pancreatic PLA2 share a high amino acid sequence homology, polyclonal antibodies directed against SPLA2 failed to recognize mammal PLA2 like the dromedary pancreatic one. Further investigations are needed to identify key residues involved in substrate recognition responsible for biochemical differences between the 2 classes of phospholipases.