Serine Esterase Research Articles

Distinct roles of an ionic interaction holding an alpha-helix with catalytic Asp and a beta-strand with catalytic His in a hyperthermophilic esterase EstE1 and a mesophilic esterase rPPE

An ionic interaction that holds an α-helix and a β-strand on which catalytic Asp and His residues are located, respectively, is conserved in a hyperthermophilic esterase EstE1 (optimum temperature 70°C) and a mesophilic esterase rPPE (optimum temperature 50°C). We investigated the role of an ionic interaction between E258 and R275 in EstE1 and that between E263 and R280 in rPPE in active-site stability of serine esterases adapted to different temperatures. Ala substitutions caused a 5-10°C decrease in the optimum temperature of both EstE1 and rPPE mutants. Surprisingly, disruption of the ionic interaction caused larger effects on the conformational flexibility of EstE1 mutants despite their rigid structures, whereas the disruption had fewer effects on the thermal stability of EstE1 mutants at 60-70°C, as the structure of EstE1 was adapted to high temperatures. In contrast, mesophilic rPPE mutants showed dramatic decreases in thermal stability at 40-50°C, but less changes in conformational flexibility because of their inherently flexible structures. The results of this study suggest that the ionic interaction between the α-helix with catalytic Asp and the β-strand with catalytic His plays an important role in the active-site conformation of EstE1 and rPPE, with larger effects on the conformational flexibility of hyperthermophilic EstE1 and the thermal stability of mesophilic rPPE.

Identification and characterization of ferulic acid esterase from Penicillium chrysogenum 31B: de-esterification of ferulic acid decorated with l-arabinofuranoses and d-galactopyranoses in sugar beet pectin

We previously described the fungus Penicillium chrysogenum 31B, which has high performance to produce the ferulic acid esterase (FAE) for de-esterifying ferulic acids (FAs) from sugar beet pulp. However, the characteristics of this fungus have not yet been determined. Therefore, in this study, we evaluated the molecular characteristics and natural substrate specificity of the Pcfae1 gene from Penicillium chrysogenum and examined its synergistic effects on sugar beet pectin. The Pcfae1 gene was cloned and overexpressed in Pichia pastoris KM71H, and the recombinant enzyme, named PcFAE1, was characterized. The 505 amino acids of PcFAE1 possessed a GCSTG motif (Gly164 to Gly168), characteristic of the serine esterase family. By comparing the amino acid sequence of PcFAE1 with that of the FAE (AoFaeB) of Aspergillus oryzae, Ser166, Asp379, and His419 were identified as the catalytic triad. PcFAE1 was purified through two steps using anion-exchange column chromatography. Its molecular mass without the signal peptide was 75 kDa. Maximum PcFAE1 activity was achieved at pH 6.0–7.0 and 50 °C. The enzyme was stable up to 37 °C and at a pH range of 3–8. PcFAE1 activity was only inhibited by Hg2+, and the enzyme had activity toward methyl FA, methyl caffeic acid, and methyl p-coumaric acid, with specific activities of 6.97, 4.65, and 9.32 U/mg, respectively, but not on methyl sinapinic acid. These results indicated that PcFAE1 acted similar to FaeB type according the Crepin classification. PcFAE1 de-esterified O-[6-O-feruloyl-β-d-galactopyranosyl-(1→4)]-d-galactopyranose, O-[2-O-feruloyl-α-l-arabinofuranosyl-(1→5)]-l-arabinofuranose, and O-[5-O-feruloyl-α-l-arabinofuranosyl-(1→3)]-O-β-d-xylopyranosyl-(1→4)-d-xylopyranose, indicating that the enzyme could de-esterify FAs decorated with both β-d-galactopyranosidic and α-l-arabinofuranosidic residues in pectin and xylan. PcFAE1 acted in synergy with endo-α-1,5-arabinanase and α-l-arabinofuranosidase, which releases FA linked to arabinan, to digest the sugar beet pectin. Moreover, when PcFAE1 was allowed to act on sugar beet pectin together with Driselase, approximately 90% of total FA in the substrate was released. Therefore, PcFAE1 may be an interesting candidate for hydrolysis of lignocellulosic materials and could have applications as a tool for production of FA from natural substrates.

Arylacetamide Deacetylase Enzyme: Presence and Interindividual Variability in Human Lungs.

Human arylacetamide deacetylase (AADAC) is a single microsomal serine esterase involved in the hydrolysis of many acetyl-containing drugs. To date, the presence and activity of the AADAC enzyme in human lungs has been scarcely examined. We investigated its gene and protein expression as well as interindividual variations in AADAC activities in a large number of human lungs (n = 25) using phenacetin as a selective substrate. The kinetic parameters K m and V max were determined. Our findings highlighted a high interindividual variability in both AADAC mRNA levels and hydrolysis activities. Furthermore, for the first time we demonstrated the presence of the AADAC protein in various lung samples by means of immunoblot analysis. As a comparison, phenacetin hydrolysis was detected in pooled human liver microsomes. Lung activities were much lower than those found in the liver. However, similar K m values were found, which suggests that this hydrolysis could be due to the same enzyme. Pulmonary phenacetin hydrolysis proved to be positively correlated with AADAC mRNA (*P < 0.05) and protein (*P < 0.05) levels. Moreover, the average values of AADAC activity in smokers was significantly higher than in nonsmoker subjects (*P < 0.05), and this might have an important role in the administration of some drugs. These findings add more information to our knowledge of pulmonary enzymes and could be particularly useful in the design and preclinical development of inhaled drugs. SIGNIFICANCE STATEMENT: This study investigated the presence and activity of the AADAC enzyme in several human lungs. Our results highlight high interindividual variability in both AADAC gene and protein expression as well as in phenacetin hydrolysis activity. These findings add more information to our knowledge of pulmonary enzymes and could be particularly useful in the design and preclinical development of inhaled drugs.

Biochemical and microbiological evaluation of N-aryl urea derivatives against mycobacteria and mycobacterial hydrolases.

A focused library of 24 N-aryl urea derivatives was prepared and evaluated against serine esterases of Mycobacterium tuberculosis (Mtb) Rv3802c and Mtb Ag85C. The members of the library were evaluated for both selectivity and mode of inhibition. Furan-based urea derivative 6c was found to be the most potent non-covalent inhibitor of Rv3802c with a K i value of 5.2 ± 0.7 μM. On the other hand, triazole-based ureas 10a and 10b selectively inhibited Ag85C irreversibly with a k inact/K i value of 2.3 ± 0.3 and 5.5 ± 0.4 × 10-3 μM-1 min-1, respectively. The library was also evaluated for minimum inhibitory concentration (MIC) against two strains of Mtb, Mycobacterium smegmatis, and Mycobacterium abscessus. Compounds 4a and 4c were active against Mtb H37Rv mc26206 with MIC values of 3.12 and 1.5 μM, respectively. Closely related 4e showed similar activity against Mtb H37Rv mc26206 but also possessed activity against Mtb H37Ra, Mycobacterium smegmatis and Mycobacterium abscessus. Compounds 4a, 4c, and 4e all contained a common 1-(cyclohexylmethyl)-3-phenylurea motif. In summary, we identified a selective non-covalent inhibitor of Rv3802c and covalently irreversible inhibitors of Ag85C as well as the 1-(cyclohexylmethyl)-3-phenylurea motif which showed activity against a variety of mycobacteria.

Computational and experimental studies on the interaction between butyrylcholinesterase and fluoxetine: implications in health and disease

Butyrylcholinesterase (BChE) is a serine esterase that plays a role in the detoxification of natural as well as synthetic ester-bond-containing compounds. Alterations in BChE activity are associated with a number of diseases. Cholinergic system abnormalities in particular are correlated with the formation of senile plaques in Alzheimer’s disease (AD), and administration of cholinesterase inhibitors is a common therapeutic approach used to treat AD.Here, our aim was to study the interaction between BChE and fluoxetine.Molecular docking simulations revealed that fluoxetine penetrated deep into the active-site gorge of BChE and that it was engaged in stabilizing noncovalent interactions with multiple subsites. In substrate kinetic studies, the Vm, Km, kcat and kcat/Km values were found to be 20.59 ± 0.36 U mg−1 protein, 194 ± 14 µM, 1.3 × 108 s−1 and 6.7 × 105 µM−1s−1, respectively. Based on inhibitory studies, fluoxetine appeared to inhibit BChE competitively, with an IC50 value of 104 µM and a Ki value of 36.3 ± 4.7 µM.Overall, both the low Ki value and the high number of BChE–fluoxetine interactions suggest that fluoxetine is a potent inhibitor of BChE, although in vivo mechanisms for the direct effects of BChE inhibition on various pathologies remain to be further investigated.

Identification of Carboxylesterase, Butyrylcholinesterase, Acetylcholinesterase, Paraoxonase, and Albumin Pseudoesterase in Guinea Pig Plasma through Nondenaturing Gel Electrophoresis.

Drugs to protect against nerve agent toxicity are tested in animals. The current preferred small animal model is guinea pigs because their plasma bioscavenging capacity resembles that of NHP. We stained nondenaturing polyacrylamide slab gels with a variety of substrates, inhibitors, and antibodies to identify the esterases in heparinized guinea pig plasma. An intense band of carboxylesterase activity migrated behind albumin. Minor carboxylesterase bands were revealed after background activity from paraoxonase was inhibited by using EDTA. The major butyrylcholinesterase band was a disulfide-linked dimer. Incubation with the antihuman butyrylcholinesterase antibody B2 18-5 shifted the butyrylcholinesterase dimer band to slower migrating complexes. Carboxylesterases were distinguished from butyrylcholinesterase by their sensitivity to inhibition by bis-p-nitrophenyl phosphate. Acetylcholinesterase tetramers formed a complex with the antihuman acetylcholinesterase antibody HR2. Organophosphorus toxicants including cresyl saligenin phosphate, dichlorvos, and chlorpyrifos oxon irreversibly inhibited the serine esterases but not paraoxonase. Albumin pseudoesterase activity was seen in gels stained with α- or β-naphthyl acetate and fast blue RR. We conclude that guinea pig plasma has 2 types of carboxylesterase, butyrylcholinesterase dimers and 5 minor butyrylcholinesterase forms, a small amount of acetylcholinesterase tetramers, paraoxonase, and albumin pseudoesterase activity. A knockout mouse with no carboxylesterase activity in plasma is available and may prove to be a better model for studies of nerve agent toxicology than guinea pigs.

Carboxylic acid reductase enzymes

A new thermostable extracellular lipolytic enzyme, induced from the thermoacidophilic archaeon Sulfolobus solfataricus P1 using corn oil as an inducer, was purified to apparent homogeneity by butanol extraction and two column chromatographies using DEAE-Sepharose followed by Butyl-Sepharose. The purified enzyme assessed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and gel filtration was approximately 45 kDa and monomeric. The maximal activity examined using p-nitrophenyl palmitate as a substrate was observed at 98 °C and pH 6.0. The enzyme showed remarkable thermostability: It retained 51% of its activity after 120 h at 80 °C. In addition, the enzyme displayed extremely high stability against water-miscible alcohols, SDS, and urea, even at high concentrations. This high stability of the enzyme against protein-denaturing agents indicates a high potential in industrial applications. The enzyme has broad substrate specificity, exhibiting not only carboxylesterase activity toward short-chain acyl esters but also lipase activity toward long-chain acyl esters including triacylglycerols regardless of saturated and unsaturated fatty acids. The kcat/Km ratios of the enzyme for p-nitrophenyl palmitate (C16), the most preferable substrate among all tested, was 93.4 s−1 μM−1. Together, it was identified by thin-layer chromatography (TLC) that the enzyme can hydrolyze all positions of the three ester bonds in triolein. The enzyme is a serine esterase belonging to the α/β hydrolase family containing a typical catalytic triad composed of serine, histidine, and aspartic acid in the active site of the enzyme. The enzyme is the first purified inducible extracellular lipolytic enzyme from archaea.

Identification of biologically active δ-lactone eicosanoids as paraoxonase substrates

The mammalian paraoxonases (PONs 1, 2 and 3) are a family of esterases that are highly conserved within and between species. They exhibit antioxidant and anti-inflammatory activities. However, their physiological function(s) and native substrates are uncertain. Previous structure-activity relationship studies demonstrate that PONs have a high specificity for lipophilic lactones, suggesting that such compounds may be representative of native substrates. This report describes the ability of PONs to hydrolyze two bioactive δ-lactones derived from arachidonic acid, 5,6-dihydroxy-eicosatrienoic acid lactone (5,6-DHTL) and cyclo-epoxycyclopentenone (cyclo-EC). Both lactones were very efficiently hydrolyzed by purified PON3. PON1 efficiently hydrolyzed 5,6-DHTL, but with a specific activity about 15-fold lower than PON3. 5,6-DHTL was a poor substrate for PON2. Cyclo-EC was a poor substrate for PON1 and not hydrolyzed by PON2. Studies with the PON inhibitor EDTA and a serine esterase inhibitor indicated that the PONs are the main contributors to hydrolysis of the lactones in human and mouse liver homogenates. Studies with homogenates from PON3 knockout mouse livers indicated that >80% of the 5,6-DHTL and cyclo-EC lactonase activities were attributed to PON3. The findings provide further insight into the structural requirements for PONs substrates and support the hypothesis that PONs, particularly PON1 and PON3, evolved to hydrolyze and regulate a class of lactone lipid mediators derived from polyunsaturated fatty acids.

Hydrolyzing activities of phenyl valerate sensitive to organophosphorus compounds paraoxon and mipafox in human neuroblastoma SH-SY5Y cells

The molecular targets of best known neurotoxic effects associated to acute exposure to organophosphorus compounds (OPs) are serine esterases located in the nervous system, although there are other less known neurotoxic adverse effects associated with chronic exposure to OPs whose toxicity targets are still not identified. In this work we studied sensitivity to the non-neuropathic OP paraoxon and to the neuropathic OP mipafox of phenyl valerate esterases (PVases) in intact and lysed human neuroblastoma SH-SY5Y cells. The main objective was to discriminate different unknown pools of esterases that might be potential targets of chronic effects from those esterases already known and recognized as targets to these acute neurotoxicity effects. Two components of PVases of different sensitivities were discriminated for paraoxon in both intact and lysed cells; while the two components inhibitable by mipafox were found only for intact cells. A completely resistant component to paraoxon of around 30% was found in both intact and lysed cells; while a component of slightly lower amplitude (around 20%) completely resistant to mipafox was also found for both preparations (intact and lysed cells). The comparison of the results between the intact cells and the lysed cells suggests that the plasma membrane could act as a barrier that reduced the bioavailability of mipafox to PVases. This would imply that the discrimination of the different esterases should be made in lysed cells. However, those studies which aim to determine the physiological role of these esterases should be necessarily conducted in intact cultured cells.

Measuring the Global Substrate Specificity of Mycobacterial Serine Hydrolases Using a Library of Fluorogenic Ester Substrates.

Among the proteins required for lipid metabolism in Mycobacterium tuberculosis are a significant number of uncharacterized serine hydrolases, especially lipases and esterases. Using a streamlined synthetic method, a library of immolative fluorogenic ester substrates was expanded to better represent the natural lipidomic diversity of Mycobacterium. This expanded fluorogenic library was then used to rapidly characterize the global structure activity relationship (SAR) of mycobacterial serine hydrolases in M.smegmatis under different growth conditions. Confirmation of fluorogenic substrate activation by mycobacterial serine hydrolases was performed using nonspecific serine hydrolase inhibitors and reinforced the biological significance of the SAR. The hydrolases responsible for the global SAR were then assigned using gel-resolved activity measurements, and these assignments were used to rapidly identify the relative substrate specificity of previously uncharacterized mycobacterial hydrolases. These measurements provide a global SAR of mycobacterial hydrolase activity, a picture of cycling hydrolase activity, and a detailed substrate specificity profile for previously uncharacterized hydrolases.

Characterization of Tetrahydrolipstatin and Stereoderivatives on the Inhibition of Essential Mycobacterium tuberculosis Lipid Esterases.

Tetrahydrolipstatin (THL) is a covalent inhibitor of many serine esterases. In mycobacteria, THL has been found to covalently react with 261 lipid esterases upon treatment of Mycobacterium bovis cell lysate. However, the covalent adduct is considered unstable in some cases because of the hydrolysis of the enzyme-linked THL adduct resulting in catalytic turnover. In this study, a library of THL stereoderivatives was tested against three essential Mycobacterium tuberculosis lipid esterases of interest for drug development to assess how the stereochemistry of THL affects respective enzyme inhibition and allows for cross enzyme inhibition. The mycolyltransferase Antigen 85C (Ag85C) was found to be stereospecific with regard to THL; covalent inhibition occurs within minutes and was previously shown to be irreversible. Conversely, the Rv3802 phospholipase A/thioesterase was more accepting of a variety of THL configurations and uses these compounds as alternative substrates. The reaction of the THL stereoderivatives with the thioesterase domain of polyketide synthase 13 (Pks13-TE) also leads to hydrolytic turnover and is nonstereospecific but occurs on a slower, multihour time scale. Our findings suggest the stereochemistry of the β-lactone ring of THL is important for cross enzyme reactivity, while the two stereocenters of the peptidyl arm can affect enzyme specificity and the catalytic hydrolysis of the β-lactone ring. The observed kinetic data for all three target enzymes are supported by recently published X-ray crystal structures of Ag85C, Rv3802, and Pks13-TE. Insights from this study provide a molecular basis for the kinetic modulation of three essential M. tuberculosis lipid esterases by THL and can be applied to increase potency and enzyme residence times and enhance the specificity of the THL scaffold.

Acetylcholinesterase of mangrove oyster Crassostrea rhizophorae: A highly thermostable enzyme with promising features for estuarine biomonitoring

Enzyme biomarkers from several aquatic organisms have been used for assessing the exposure to contaminants at sublethal levels. Amongst them, the cholinesterases are commonly extracted from several organisms to evaluate/measure organophosphate and carbamate neurotoxic effects. Acetylcholinesterase (AChE; EC 3.1.1.7) is an enzyme of the group of serine esterases that acts on the hydrolysis of the neurotransmitter acetylcholine allowing the intermittence of the nerve impulses responsible for the neuronal communication. This enzyme is the main target for the action of some pesticides and the inhibition of its activity in bivalve mollusks may be used as biomarker due to their filter-feeding habit. In this context, the present study aimed to characterize physicochemical and kinetic parameters of the AChE extracted from gills and viscera of the oyster Crassostrea rhizophorae and investigate the in vitro effect of pesticides (dichlorvos, diazinon, chlorpyrifos, methyl-parathion, temephos, carbaryl, carbofuran, aldicarb, diflubenzuron and novaluron) in search for assessing its potential as biomarker. Specific substrates and inhibitors evidenced the predominance of AChE in both tissues. The optimum pH found for gills and viscera AChE were 8.0 and 8.5, respectively. The maximum peak of activity occurred at 70 °C for gill AChE and 75 °C for viscera AChE. The enzymes of both tissues presented remarkable thermostability. The Michaelis-Menten constant for both enzymes were 1.32 ± 0.20 mM for gills and 0.43 ± 0.12 mM for viscera. The Vmax values for gills and viscera were 53.57 ± 1.72 and 27.71 ± 1.15 mU/mg, respectively. The enzymes were able to reduce the activation energy to 9.75 kcal mol−1 (gills) and 11.87 kcal mol−1 (viscera) obtaining rate enhancements of 3.57 × 105 and 1.01 × 104, respectively, in relation to non-catalyzed reactions. Among the pesticides under study, the carbamates carbaryl and carbofuran exerted the strongest inhibitory effects on the enzyme activity achieving important degrees of inhibition at concentrations below national and international current regulations. The first observation of the effects of benzoylurea pesticides (diflubenzuron and novaluron) on AChE from mollusks is reported here. The gills AChE of C. rhizophorae showed potential to be specific biomarker for the carbamate carbaryl while the viscera AChE showed it for carbofuran. According to their features, these enzymes may be proposed as promising tools for estuarine monitoring as well as biocomponent of biosensor devices.

Immunosuppressive mechanism of Hypoderma lineatum secreted serine esterase, a potential modulatory method used to inhibit transplant rejection

Background: Although immunosuppressive therapies have made organ transplantation a common medical procedure worldwide, chronic toxicity has a major issue for long-term treatment. One method to improve therapies and methods is the application of immunomodulatory agents from parasites such as Hypoderma lineatum. Hypodermin A (HA) is a serine esterase secreted by the larvae of Hypoderma lineatum, several studies demonstrated its immunosuppressive mechanism in vitro, and recently we discovered that HA inhibits the expression of interferon (IFN)-γ and interleukin (IL)-2 and activates IL-10 expression. Therefore, we hypothesized that it might be a potential agent used to block allograft rejections. However, most studies of the immunosuppressive mechanisms associated with HA were undertaken at the cellular level. In order to augment these studies, we evaluated the immunosuppressive effects of HA in vivo using an HA transgenic mouse model. Result: Our results revealed similar findings to those reported by in vitro studies, specifically that HA induced prostaglandin E2 expression, downregulated IFN-γ and IL-2 expression, and promoted IL-10 secretion via E-type prostanoid receptor 4. Additionally, we observed that HA overexpression inhibited lipopolysaccharide-induced TLR4 activation. These findings provide insight into a new potential agent capable of blocking graft rejection. Conclusion: Our founding suggested that HA-related treatment could be a promising option to improve the viability of grafts in human.

Loop of Streptomyces Feruloyl Esterase Plays an Important Role in the Enzyme's Catalyzing the Release of Ferulic Acid from Biomass.

Feruloyl esterases (FAEs) are key enzymes required for the production of ferulic acid from agricultural biomass. Previously, we identified and characterized R18, an FAE from Streptomyces cinnamoneus NBRC 12852, which showed no sequence similarity to the known FAEs. To determine the region involved in its catalytic activity, we constructed chimeric enzymes using R18 and its homolog (TH2-18) from S. cinnamoneus strain TH-2. Although R18 and TH2-18 showed 74% identity in their primary sequences, the recombinant proteins of these two FAEs (recombinant R18 [rR18] and rTH2-18) showed very different specific activities toward ethyl ferulate. By comparing the catalytic activities of the chimeras, a domain comprised of residues 140 to 154 was found to be crucial for the catalytic activity of R18. Furthermore, we analyzed the crystal structure of rR18 at a resolution of 1.5 Å to elucidate the relationship between its activity and its structure. rR18 possessed a typical catalytic triad, consisting of Ser-191, Asp-214, and His-268, which was characteristic of the serine esterase family. By structural analysis, the above-described domain was found to be present in a loop-like structure (the R18 loop), which possessed a disulfide bond conserved in the genus Streptomyces Moreover, compared to rTH2-18 of its parental strain, the TH2-18 mutant, in which Pro and Gly residues were inserted into the domain responsible for forming the R18 loop, showed markedly high kcat values using artificial substrates. We also showed that the FAE activity of TH2-18 toward corn bran, a natural substrate, was improved by the insertion of the Gly and Pro residues.IMPORTANCEStreptomyces species are widely distributed bacteria that are predominantly present in soil and function as decomposers in natural environments. They produce various enzymes, such as carbohydrate hydrolases, esterases, and peptidases, which decompose agricultural biomass. In this study, based on the genetic information on two Streptomyces cinnamoneus strains, we identified novel feruloyl esterases (FAEs) capable of producing ferulic acid from biomass. These two FAEs shared high similarity in their amino acid sequences but did not resemblance any known FAEs. By comparing chimeric proteins and performing crystal structure analysis, we confirmed that a flexible loop was important for the catalytic activity of Streptomyces FAEs. Furthermore, we determined that the catalytic activity of one FAE was improved drastically by inserting only 2 amino acids into its loop-forming domain. Thus, differences in the amino acid sequence of the loop resulted in different catalytic activities. In conclusion, our findings provide a foundation for the development of novel enzymes for industrial use.

Effect of plant secondary metabolites on common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

AbstractThe effect of various flavonoids, lectins and phenyl β‐D‐glucoside on larval survival, weights and the activities of digestive (total serine protease and trypsin) and detoxifying (esterase and glutathione‐S‐transferase) enzymes of Spodoptera litura larvae at 7 days after treatment was studied through diet incorporation assay. Flavonoids (rutin, chlorogenic acid, quinic acid, caffeic acid, naringenin, quercitin, kaempferol, myricetin, catechin, and ferulic acid) were incorporated in artificial diet at 100, 500 and 1000 ppm, lectins: groundnut leaf lectin (GLL), concavalin A (ConA) and phenyl β‐D‐glucoside at 1, 2 and 5 μg/mL. Flavonoids such as rutin, quercitin and kaempferol at 1000 ppm were more toxic to S. litura larvae than quinic acid, caffeic acid, naringenin, myricetin, catechin, and ferulic acid. Larval growth and development were significantly reduced in S. litura larvae fed on a diet with GLL and ConA at 5 μg/mL compared to the larvae fed at 2 and 1 μg/mL concentrations. The larvae fed on flavonoid‐treated diets showed significant reduction in serine protease, trypsin and esterase activities. The flavonoids such as rutin, chlorogenic acid, quinic acid, naringenin, quercitin, kaempferol and myricetin, and lectins, GLL and ConA can be utilized in insect control programs.

Unraveling the venom components of an encyrtid endoparasitoid wasp Diversinervus elegans

The encyrtid parasitoid, Diversinervus elegans (Hymenoptera: Encyrtidae), is a natural enemy of the notorious scale pests belonging to the family of Coccidae. Venom containing a rich source of bioactive molecules is a key virulent factor used to regulate host physiology by parasitoids. Although knowledge regarding venom constituents accumulated from limited parasitoids has provided insights into their roles in host-parasitoid interaction, toxins involving in manipulating scale physiology remain sparsely documented. Here, a total number of 48 putative venom proteins were identified from D. elegans using an integrative transcriptomic and proteomic approach. The majority of them such as serine protease, esterase, and major royal jelly protein have been found in venom of other several parasitoid species. Several venom proteins including three novel proteins having unknown function were firstly revealed. Quantitative real time PCR analysis demonstrated that 16 venom genes displayed female-biased expression, which might be important for parasitism success. These data enrich our understanding of parasitoid venom evolution and diversity, and will undoubtedly help deciphering functional venom proteins as potential candidates for pest control.

The novel carboxylesterase 1 variant c.662A&gt;G may decrease the bioactivation of oseltamivir in humans

BackgroundHuman carboxylesterase 1 (CES1) is a serine esterase that hydrolyses various exogenous and endogenous compounds including oseltamivir, a prodrug used to treat influenza. A novel CES1 c.662A>G single nucleotide polymorphism (SNP) was predicted to decrease CES1 enzymatic activity in an in silico analysis. This study evaluated the effect of the c.662A>G SNP on the pharmacokinetics (PK) of oseltamivir in humans.MethodsA single oral dose of oseltamivir at 75 mg was administered to 20 healthy subjects, 8 heterozygous c.662A>G carriers (c.662AG) and 12 non-carriers (c.662AA). The concentrations of oseltamivir and its active metabolite, oseltamivir carboxylate, were measured in plasma and urine using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The PK parameters were calculated using a noncompartmental method. The geometric mean ratios (GMR, c.662AG to c.662AA) of the PK parameters and their 90% confidence intervals (CI) were calculated.ResultsThe systemic exposure to oseltamivir, as assessed by the AUC0-48h of oseltamivir, was increased by 10% in c.662AG subjects, whereas the AUC0-48h of oseltamivir carboxylate was 5% lower in c.662AG subjects. The GMR and 90% CI of the metabolic ratio (AUC0-48h, Oseltamivir carboxylate/AUC0-48h, Oseltamivir) was 0.87 (0.66–1.14). The amount of unchanged oseltamivir excreted in the urine was increased by 15% in subjects with the c.662AG genotype.ConclusionsThis result suggests that CES1 enzymatic activity may be decreased in these heterozygous allele carriers, although further studies are warranted to investigate the clinical implications of this genetic variation on CES1 substrate drugs.Trial registrationClinicalTtrials.gov NCT01902342

GENDER SPECIFIC CHANGES IN MOUSE BLOOD ESTRERASE PROFILE AT THE ACUTE INTOXICATION BY 2-(О-CRESYL)-4Н-1,3,2-BENZODIOXAPHOSPHORIN-2-OXIDE

A comparative investigation of the esterase profiles of blood of mice of both genders exposed to various doses of 2-(o-crezyl)-4H-1,3,2-benzodioxaphosphorin-2-oxide (CBDP) was made an hour after its percutaneous injection to animals. A lesser amount of esterase in males blood made them more susceptible to CBDP action as compared to females. It was shown that CBDP equally inhibits the activity of carboxyl esterase and butyryl choline esterase in blood serum of both male and female mice. Statistically significant differences in inhibition degree of enzymes between males and females were found out and therefore it is not recommended to use mixed groups of animals when performing testing of serine esterase inhibitors.

Expression of Cellulolytic Enzyme as a Fusion Protein That Reacts Specifically With a Polymeric Scaffold.

The formation of higher-order assemblies of multiple proteins or enzymes is a general mechanism to achieve more sophisticated biological function in biological systems. For example, cellulosomes are large complexes consisting of multiple cellulolytic enzymes that rely on the concerted actions of different enzymes built onto a common protein scaffold to facilitate the breakdown of the polymeric substrate, cellulose. One strategy for mimicking these highly effective nanomachines may involve the use of synthetic scaffolds that can react to and organize multiple engineered enzymes to promote synergistic action between the enzymes on the scaffold. As an example of the earlier strategy, we describe here an approach for the expression of cellulolytic enzymes with a serine esterase tag, and the rapid reaction between the tag and the end-functionalized polymers to form enzyme-polymer-enzyme multienzyme conjugates. In principle, this general and versatile supramolecular approach may be used to organize specific cellulolytic enzymes onto synthetic scaffolds to form multienzyme complexes to potentially work in synergy for enhanced biological activities. Best reaction conditions, good activities of the armored cellulolytic enzymes and the design of optimal protein linker in the fusion protein are discussed in detail. If other reactive tags are included on the enzyme in future, multiple types of synergistic enzymes may be positioned at specific sites on a designed polymer scaffold that mimics the complex structure and enhanced function of natural cellulosomes. This type of nanoarmoring of multiple enzymes on a nanoscale might also enhance enzyme stability, when compared to the unprotected enzymes.

Characterisation of a New Family of Carboxyl Esterases with an OsmC Domain.

Proteins in the serine esterase family are widely distributed in bacterial phyla and display activity against a range of biologically produced and chemically synthesized esters. A serine esterase from the psychrophilic bacterium Pseudoalteromonas arctica with a C-terminal OsmC-like domain was recently characterized; here we report on the identification and characterization of further putative esterases with OsmC-like domains constituting a new esterase family that is found in a variety of bacterial species from different environmental niches. All of these proteins contained the Ser-Asp-His motif common to serine esterases and a highly conserved pentapeptide nucleophilic elbow motif. We produced these proteins heterologously in Escherichia coli and demonstrated their activity against a range of esterase substrates. Two of the esterases characterized have activity of over two orders of magnitude higher than other members of the family, and are active over a wide temperature range. We determined the crystal structure of the esterase domain of the protein from Rhodothermus marinus and show that it conforms to the classical α/β hydrolase fold with an extended ‘lid’ region, which occludes the active site of the protein in the crystal. The expansion of characterized members of the esterase family and demonstration of activity over a wide-range of temperatures could be of use in biotechnological applications such as the pharmaceutical, detergent, bioremediation and dairy industries.