Characterization of a Novel Esterase Belonging to Family V from Marinobacter flavimaris

Lipolytic enzymes have attracted enormous attentions because of their ability in ester hydrolysis,ester synthesis,transesterification and other biochemical reactions.Bacteria are important sources of lipolytic enzymes applied in industry.Here,a novel lipolytic enzyme encoded by esterase gene est1347 was identified in Marinobacter flavimaris WLL162,and was purified and characterized.The lipolytic enzyme Est1347 consisted of 312 amino acid residues and a 21-amino-acids N-terminal signal peptide with a predicted molecular weight of 34.2 kDa.It belongs to family V of bacterial lipolytic enzymes based on the amino acid sequence homology analysis.Est1347 is a mesophilic and alkali-resistant enzyme with the highest activity at 45℃and pH 8.5;it is stable at temperatures below 50℃and pH 7.5–11.0.Est1347 showed a preference for middle-length chain substrate p-NPC10 and a wide range of other substrates.The Km,Vmax,Kcat and Kcat/Km values of Est1347 for p-NPC10 in pH 8.5 at 45℃were 0.9411 mmol L^(−1),1285μmol min^(−1)mg^(−1),698.91 s^(−1)and 743.65 s^(−1)(mmol L^(−1))^(−1),respectively.It is also tolerant to the metal ions,organic solvents and detergents.In conclusion,the esterase Est1347 laid a foundation for further study of bacterial lipolytic enzyme family V.

Biochemical Insights into Siderophore Esterases

Iron is an essential but excessively toxic nutrient. Although iron is rich in nature, the acquisition of iron is a challenge to life. Its solubility is very low because it is mostly in the form of oxidation or hydroxide. In order to overcome this, microorganisms have evolved a variety of iron absorption pathways, the most important of which is the siderophore-dependent iron absorption pathway. Both bacteria and fungi require specific siderophore esterases to encourage the release of iron within the cell. A deeper understanding of siderophore esterases is crucial for the development of new antibacterial and antifungal diagnostic and therapeutic approaches. There have been many recent studies on anti-infectives via siderophore antibiotic couplers in which siderophore esterases have also played an important role, and in this review, we provide an overview of several of the more common iron carriers as well as siderophore esterases in terms of structure as well as function.

Inhibitory effect of procyanidin B2 and tannin acid on cholesterol esterase and their synergistic effect with orlistat

This study was aimed to analyze the effect of procyanidin B2(PC)and tannin acid(TA)on the activities of cholesterol esterase(CEase)and the inhibitory mechanisms of enzymatic activity.The interaction mechanisms were investigated by enzymatic kinetics,multi-spectroscopy methods,thermodynamics analysis,molecular docking,and dynamic simulations.PC and TA could bind with CEase and inhibit the activity of enzyme in a mixed-competitive manner and non-competitive manner,which was verified by molecular docking simulations and dynamics simulations.Also,PC and TA showed the synergistic inhibition with orlistat.Fluorescence,UVvis and the thermodynamic analysis revealed that the complexes were formed from CEase and inhibitors by noncovalent interaction.As revealed by the circular dichroism results,both PC and TA decreased enzymatic activities by altering the conformations of CEase.The inhibition of PC and TA on CEase might be one mechanism for its cholesterol-lowering effect.

Emerging significance of butyrylcholinesterase

Butyrylcholinesterase(BChE;EC 3.1.1.8),an enzyme structurally related to acetylcholinesterase,is widely distributed in the human body.It plays a role in the detoxification of chemicals such as succinylcholine,a muscle relaxant used in anesthetic practice.BChE is well-known due to variant forms of the enzyme with little or no hydrolytic activity which exist in some endogamous communities and result in prolonged apnea following the administration of succinylcholine.Its other functions include the ability to hydrolyze acetylcholine,the cholinergic neurotransmitter in the brain,when its primary hydrolytic enzyme,acetylcholinesterase,is absent.To assess its potential roles,BChE was studied in relation to insulin resistance,type 2 diabetes mellitus,cognition,hepatic disorders,cardiovascular and cerebrovascular diseases,and inflammatory conditions.Individuals who lack the enzyme activity of BChE are otherwise healthy,until they are given drugs hydrolyzed by this enzyme.Therefore,BChE is a candidate for the study of loss-of-function mutations in humans.Studying individuals with variant forms of BChE can provide insights into whether they are protected against metabolic diseases.The potential utility of the enzyme as a biomarker for Alzheimer’s disease and the response to its drug treatment can also be assessed.

Effects of inoculating feruloyl esterase-producing Lactiplantibacillus plantarum A1 on ensiling characteristics,in vitro ruminal fermentation and microbiota of alfalfa silage

Background Ferulic acid esterase(FAE)-secreting Lactiplantibacillus plantarum A1(Lp A1)is a promising silage inoculant due to the FAE’s ability to alter the plant cell wall structure during ensiling,an action that is expected to improve forage digestibility.However,little is known regarding the impacts of Lp A1 on rumen microbiota.Our research assessed the influences of Lp A1 in comparison to a widely adopted commercial inoculant Lp MTD/1 on alfalfa’s ensilage,in vitro rumen incubation and microbiota.Results Samples of fresh and ensiled alfalfa treated with(either Lp A1 or Lp MTD/1)or without additives(as control;CON)and ensiled for 30,60 and 90 d were used for fermentation quality,in vitro digestibility and batch culture study.Inoculants treated silage had lower(P<0.001)pH,acetic acid concentration and dry matter(DM)loss,but higher(P=0.001)lactic acid concentration than the CON during ensiling.Compared to the CON and Lp MTD/1,silage treated with Lp A1 had lower(P<0.001)aNDF,ADF,ADL,hemicellulose,and cellulose contents and higher(P<0.001)free ferulic acid concentration.Compared silage treated with Lp MTD/1,silage treated with Lp A1 had significantly(P<0.01)improved ruminal gas production and digestibility,which were equivalent to those of fresh alfalfa.Realtime PCR analysis indicated that Lp A1 inoculation improved the relative abundances of rumen’s total bacteria,fungi,Ruminococcus albus and Ruminococcus flavefaciens,while the relative abundance of methanogens was reduced by Lp MTD/1 compared with CON.Principal component analysis of rumen bacterial 16S rRNA gene amplicons showed a clear distinction between CON and inoculated treatments without noticeable distinction between Lp A1 and Lp MTD/1 treatments.Comparison analysis revealed differences in the relative abundance of some bacteria in different taxa between Lp A1 and Lp MTD/1 treatments.Silage treated with Lp A1 exhibited improved rumen fermentation characteristics due to the inoculant effects on the rumen microbial populations and bacterial community.Conclusions Our findings suggest that silage inoculation of the FAE-producing Lp A1 could be effective in improving silage quality and digestibility,and modulating the rumen fermentation to improve feed utilization.

Characterization ofanovel deep-seamicrobial esterase EstC 10 and its use in the generation o f(R)-methyl 2-chloropropionate

A novel esterase Est C10 from B acillus sp. CX01 isolated from the deep sea of the Western Pacific Ocean and the functionalities of Est C10 was characterized. At present, the reports about the kinetic resolution of racemic methyl 2-chloropropionate were quite rare. So we developed deep-sea microbial esterase Est C10 as a novel biocatalyst in the kinetic resolution of racemic methyl 2-chloropropionate and generate( R)-methyl 2-chloropropionate with high enantiomeric excess(>99%) after the optimization of process parameters such as p H, temperature, organic co-solvents, surfactants, substrate concentration and reaction time. Notably, the optimal substrate concentration(80 mmol/L) of esterase Est C10 was higher than the kinetic resolution of another esterase, Est12-7(50 mmol/L). The novel microbial esterase Est C10 identified from the deep sea was a promising green biocatalyst in the generation of( R)-methyl 2-chloropropionate as well of many other valuable chiral chemicals in industry.

Sub-Lethal Effects of Fenvalerate on the Development, Fecundity, and Juvenile Hormone Esterase Activity of Diamondback Moth, Plutella xylostella (L.)

The toxicities of fenvalerate （20% EC） to the 3rd instar larvae of diamondback moth （DBM）, Plutella xylostella （L.）, reared on three host plants viz., radish, oilseed rape, and cabbage were tested. The LC50 values of fenvalerate to the 3rd instar larvae of DBM varied with host plants, however, there wasn＇t any significant difference among them （P〉 0.05）. Similarly, DBM fed on three host plants had same pupal weight, pupal period, pupation rate, adult emergence rate, female ratio, and fecundity. The activity of juvenile hormone esterase （JHE, EC 3.1.1.1） in the 3rd instar larvae of DMB did not significantly vary with host plants, either. These suggested that DBM had similar fitness on the three host plant species. When fed on the host plants pretreated with fenvalerate at the concentrations equivalent to LC20, LC50 and LC50, the pupation rate, pupal weight, adult emergence rate, female ratio, fecundity, and JHE activity of the tested insects were declined as compared with insects in control treatments fed on the same host plant species. Furthermore, the pupal period of the tested insects was extended after fenvalerate treatment. The decrease in JHE activity after fenvalerate treatment in the tested insects could partly explain the changes in the mentioned growth parameters. Whether the role of fenvalerate in the inhibition of JHE activity could serve as a new way to control DBM needs further investigation.

Cancer detection by ubiquitin carboxyl-terminal esterase L1 methylation in pancreatobiliary fluids

AIM:To evaluate the utility of measuring epigenetic alterations in pancreatic and biliary fluids in determining molecular markers for pancreatobiliary cancers.METHODS:DNA was extracted from undiluted pancreatic and biliary fluids.As a surrogate for a genomewide hypomethylation assay,levels of long interspersed nuclear element-1(LINE-1) methylation were analyzed using bisulfite pyrosequencing.CpG island hypermethylation of 10 tumor-associated genes,aryl-hydrocarbon receptor repressor,adenomatous polyposis coli,calcium channel,voltage dependent,T type α1G subunit,insulin-like growth factor 2,O-6-methyl-guanine-DNA methyltransferase,neurogenin 1,CDKN2A,runt-related transcription factor 3(RUNX3),secreted frizzled-related protein 1,and ubiquitin carboxyl-terminal esterase L1(UCHL1),was analyzed using MethyLight.To examine the role of CpG methylation and histone deacetylation in the silencing of UCHL1,human gallbladder carcinoma cell lines and pancreatic carcinoma cell lines were treated with 2 or 5 μmol/L 5-AZA-dC for 72 h or 100 nmol/L Trichostatin A for 24 h.After the treatment,UCHL1 expression was analyzed by real-time reverse transcription-polymerase chain reaction.RESULTS:Pancreatobiliary cancers exhibited significantly lower LINE-1 methylation levels in pancreatic and biliary fluids than did noncancerous pancreatobiliary disease(58.7% ± 4.3% vs 61.7% ± 2.2%,P = 0.027;53.8% ± 6.6% vs 57.5% ± 1.7%,P = 0.007);however,LINE-1 hypomethylation was more evident in pancreatic cancer tissues than in pancreatic fluids(45.4% ± 5.5% vs 58.7% ± 4.3%,P < 0.001).CpG island hypermethylation of tumor-associated genes was detected at various frequencies,but it was not correlated with LINE-1 hypomethylation.Hypermethylation of the UCHL1 gene was cancer-specific and most frequently detected in pancreatic(67%) or biliary(70%) fluids from patients with pancreatobiliary cancer.As a single marker,hypermethylation of the UCHL1 gene in pancreatic and biliary fluids was most useful for the detection of pancreatic and pancreatobiliary cancers,respectively(100% specificity).Hypermethylation of the UCHL1 and RUNX3 genes in pancreatic and biliary fluids was the most useful combined marker for pancreatic(87% sensitivity and 100% specificity) and pancreatobiliary(97% sensitivity and 100% specificity) cancers.Treatment with a demethylating agent,5-AZA-2'-deoxycytidine,restored UCHL1 expression in pancreatobiliary cancer cell lines.CONCLUSION:Our results suggest that hypermethylation of UCHL1 and RUNX3 in pancreatobiliary fluid might be useful for the diagnosis of pancreatobiliary cancers.

Carboxylic Esterase and Its Associations With Long-term Effects of Organophosphorus Pesticides

To examine a） the effect of organophosphorus pesticide exposure on activity of carboxylic esterases, namely butyrylcholinesterase （BChE）, carboxylesterase （CarbE） and paraoxonase （PonE）; and b） the association of polymorphisms of BChE and PonE with individual genetic susceptibility to organophosphorus pesticide exposure. Methods A cross-sectional study was conducted in 75 workers exposed to organophosphorus pesticides and 100 non-exposed controls. The serum activity of these enzymes was measured. Variant forms of BCHE-K, PON-192, and PON-55 were detected. A symptom score was developed as a proxy measure of clinical outcomes. Results Activities of both BChE and CarbE were lower in exposed workers （27.3±21.65 runol.hl.mL^-l and 235.6±104.03 nmol-min^-l.mL^-l） than in non-exposed workers （78.313±30.354 nmol.h^-l.mL^-1 and 362.681_＋194.997 nmol.min^-1.mL^-1）. The activity of PonE was not associated with exposure status. The AChE activity in the exposed workers with BCHE-K genotype UU （61 cases）, genotype UK （12 cases） and genotype KK （2 cases） was 105.05, 84.42 and 79.00 mmol-h^-1.mL^-1, respectively and the accumulative symptom scores were 3.74, 9.17, and 12.50 accordingly. The AChE activity in the exposed workers with PON-192 genotype BB （37）, genotype AB （27） and genotype AA （11） was 116.8, 91.2, and 72,3 mmol-h^-1.mL^-1, respectively and the symptom scores were 2.00, 6.74, and 9.73 accordingly. The AChE activity in those with PON-55 genotype LL （70） and genotype LM （5） was 102.4 and 82.8 mmol-h^-1.mL^-1 and the symptom scores were 4.53 and 9.20. The symptom score was the highest in individuals with abnormal homozygote for each of the three gene loci. Condusions Long-term exposure to organophosphorus pesticides can inhibit BChE and CarbE activity, but exerts no inhibitory effect on PonE activity. Different genotypes of BCHE-K, PON-192, and PON-55 may be related to the severity of adverse health effects of organophosphorus pesticide exposure. Implications of potentially higher susceptibility of workers with mutant homozygotes should be evaluated to reduce health risks.

Comparative Study of Malathion Toxicity and General Esterases in Larvae and Adults from a Field Population of Oxya chinensis (Thunberg) (Orthoptera: Acridoidea)

The susceptibility of Oxya chinensis to malathion was compared in larvae and adults from a field population, collected from Jinyuan outskirt, Shanxi Province. The results showed that Oxya chinensis was more susceptible to malathion in the adult stage than in the larval stage. The LD50 values for malathion susceptibility of Oxya chinensis were 4.94 and 2.44 mg g-1 body weight in the larvae and adults respectively. The results indicated that the larvae were 2.02-fold less susceptible to malathion than the adults. The general esterases and the kinetics were characterized and compared between the two life stages and between females and males. Larval preparations of Oxya chinensis were more active than adult preparations in females and males. The larvae showed 1.18-, 1.49-, and 1.17- fold higher specific activities than the adults in females with α-NA, α-NB and β-NA respectively. In males, the ratios were 1.34-, 1.70-, and 1.06-fold. Female preparations were more active than those of males in the adults. The reverse results were observed in the larvae where male preparations were more active than female preparations. Kinetic studies showed that Km values of general esterases hydrolyzing α-NA, α-NB, and β-NA in the adult stage were 1.36-, 1.32- and 1.39-fold respectively, higher than those in the larval stage in females. In males, the ratios were 1.24-, 2.14-, and 1.20-fold. The esterase from male insects had a higher affinity (lower Km value) to the substrate than those from females. The results also showed that the Vmax values of general esterase hydrolyzing α-NA, α-NB, and β-NA in the two stages were similar. From the results of bioassays and biochemical analyses, it has been inferred that a higher level of resistance to malathion in larvae than in adults would appear to result from differences in the expression of resistance mechanisms in these two life stages. Enhanced esterase activities appeared to play a major role in resistance to malathion in both larvae and adults. From the analysis of inhibition in vitro, the esterases in the two life stages were B-type, and carboxylesterases were predominant enzymes in the composition of the esterases in the two stages.

Denaturing Effects of Urea and Guanidine Hydrochloride on Hyperthermophilic Esterase from Aeropyrum pernix K1

The changes in the activity and the conformation of the hyperthermophilic esterase derived from aerobic thermophilic Aeropyrum pernix K1 （ APE1547 ） were studied during denaturation by guanidine hydrochlofide （ GdnHC1 ） and urea. The denaturation course of APE1547 was followed by the steady-state and time resolved fluorescence methods. An increase in the denaturant concentration in the denatured system can significantly enhance the inactivation and unfolding of APE1547. The enzyme can be completely inactivated with a urea concentration of 2.7 mol/L or a GdnHCl concentration of 7.5 mol/L. The fluorescence emission maximum of the enzyme protein red shifts in magnitude to a maximum value（355 nm） when the concentration of GdnHCl is 5.1 mol/L. The experimental results indicate that APE1547 has a high resistance to urea. Unfolding of APE1547 in GdnHCI（4. 2-6.0 mol/L） was shown to be an irreversible process. The present results indicate that the ion pairs in this protein may be a key factor for the stability of this esterase.

Effect of Schisandra chinensis polysaccharide on intracerebral acetylcholinesterase and monoamine neurotransmitters in a D-galactose-induced aging brain mouse model

BACKGROUND： The most prominent characteristic of brain aging is decreased learning and memory ability. The functions of learning and memory are closely related to intracerebral acetylcholinesterase （ACHE） and monoamine neurotransmitter activity. Previous studies have shown that Schisandra chinensis polysaccharide has an anti-aging effect. OBJECTIVE： To explore the effects of Schisandra chinensis polysaccharide on AChE activity and monoamine neurotransmitter content, as well as learning and memory ability in a D-galactose-induced aging mouse brain model compared with the positive control drug Kangnaoling. DESIGN, TIME AND SETTING： Completely randomized, controlled experiment based on neurobiochemistry was performed at the Pharmacological Laboratory, Henan University of Traditional Chinese Medicine from September to December 2003. MATERIALS： Schisandra chinensis was purchased from Henan Provincial Medicinal Company. Schisandra chinensis polysaccharide was obtained by water extraction and alcohol precipitation. Kangnaoling pellets were provided by Liaoning Tianlong Pharmaceutical （batch No. 20030804; state drug permit No. H21023095）. A total of 50 six-week-old Kunming mice were randomly divided into five groups： blank control, model, Kangnaoling, high and low dosage Schisandra chinensis polysaccharide groups, with 10 mice per group. METHODS： Mice in the blank control group were subcutaneously injected with 0.5 mL/20 g normal saline into the nape of the neck each day, while the remaining mice were subcutaneously injected with 5% D-galactose saline solution （0.5 mL/20 g） in the nape for 40 days to induce a brain aging model. On day 11, mice in the high and low dosage Schisandra chinensis polysaccharide groups were intragastrically infused with 20 mg/mL and 10 mg/mL Schisandra chinensis polysaccharide solution （0.2 mL/10 g）, respectively. Mice from the Kangnaoling group were intragastrically infused with 35 mg/mL Kangnaoling suspension （0.2 mL/10 g）, and the mice in the model group were intragastrically infused with the same volume of normal saline （0.2 mL/10 g） once per day for 30 consecutive days. MAIN OUTCOME MEASURES： Two hours after the final administration, pathohistological changes in the cerebral cortex and hippocampus were observed using hematoxylin ＆ eosin staining. AChE activity was detected using chromatometry. Monoamine neurotransmitter content was measured using fluorimetry. Learning and memory was measured using the step down test and darkness avoidance test. RESULTS： Both Schisandra chinensis polysaccharide and Kangnaoling improved pathological injury to the cerebral cortex and hippocampus in a mouse model of brain aging. Compared with the blank control group, AChE activity and content of norepinephrine （NA）, dopamine （DA）, and 5-hydroxytryptamine （5-HT） were significantly decreased in the model group （P 〈 0.01 ）. In contrast, AChE activity and NA, DA, and 5-HT levels significantly increased in the Kangnaoling and high dosage Schisandra chinensis polysaccharide groups （P 〈 0.01）, while NA levels significantly increased in the low dosage Schisandra chinensis polysaccharide group （P 〈 0.01）. Drug treatment improved learning and memory abilities （P 〈 0.01 or P 〈 0.05）. CONCLUSION： Schisandra chinensis polysaccharide significantly increased levels of central neurotransmitters and improved learning and memory in a mouse model of brain aging. The effects of Schisandra chinensis polysaccharide were equal to that of Kangnaoling pellets.

Functional characterization of a novel microbial esterase identified from the Indian Ocean and its use in the stereoselective preparation of(R)-methyl mandelate

Genomic mining has identifi ed a novel microbial alkaline esterase from the Indian Ocean. This esterase was overexpressed in E. coli BL21(DE3) and further functionally characterized. Under optimal conditions(10 mmol/L substrate, p H 6.0, 2 h at 40 °C), this esterase can hydrolyze racemic methyl mandelate to( R)-methyl mandelate with very high optical purity(e. e. >99%) and yield(nearly 90%). Interestingly, the stereoselectivity of this esterase is opposite to that of two previously reported lipases that can generate( S)-methyl mandelate through the hydrolysis of racemic methyl mandelate. No organic solvents or other additives were required to optimize the optical purity and production of the fi nal chiral product(R)-methyl mandelate, which can potentially simplify the production procedure of( R)-methyl mandelate catalyzed by esterase.

Isolation and Characterization of Two Novel Gene Encoded Alkaline Esterases from an Alkaline Soil Metagenomic Library

The development of industrial biotechnology has created an increasing demand for alkaline lipolytic enzymes with functional diversity. In this study, an alkaline soil metagenomic library was constructed to search for new lipolytic enzymes. Two novel gene encoded alkaline esterases（designated as estA and estB） were isolated by functional screening from the library. The estA gene consisted of 834 bp and coded for 277 amino acids with a molecular mass of 29998. Amino acid sequence homology analysis indicates that EstA belongs to α/β hydrolase fold family 4.4（abH4.4）, with EstA being the smallest member of that family yet reported. The estB gene consisted of 1185 bp and encoded 394 amino acids with a theoretical molecular mass of 40090. Its conserved domain analysis shows that EstB belongs to the GDSL hydrolase superfamily. Both EstA and EstB exhibit only moderate identity（〈38%） in amino acid sequence to the known lipolytic enzyme genes in the database. The two genes were respectively expressed in Escherichia coli and the protein products were purified for functional characterization. While the expressed EstA did not exhibit the functional properties that were superior to those of other esterases previously reported, the EstB was stable at temperature up to 45 ℃ and its maximum activity was measured to be 53.6 U/mg at pH=10. Both the en- zymes have further enriched the diversity of the lipolytic enzymes database and also appear to be promising biocatalysts for potential biotechnological application.

The Susceptibilities of Oxya chinensis(Orthoptera:Acridoidea) to Malathion and Comparison of the Esterase Properties from Three Collected Populations in Tianjin Area,China

The susceptibilities of Oxya chinensis to malathion were studied in three populations collected from outskirt of Tianjin, China, using bioassays and biochemical analysis. Populations were chosen to represent different exposure to insecticides： BDG （Beidagang; low exposure）, BD （Baodi; high exposure previously but low exposure now）, and JN （Jinnan; high exposure）. The results showed that the LD50 values of BD and JN populations were 3.95- and 12.02-fold and 3.64- and 10.07- fold higher than that of BDG population in females and males, respectively. The LD50 values in females were higher than those in males. The results of biochemical analysis indicated that the esterase （EST） activities in JN population were higher than those in BD and BDG populations. They showed that when α-NA, α-NB, and α-NA were used as substrates, females＇ EST activities of JN population were 1.11-, 1.30-, and 1.14-fold and 1.39-, 1.59-, and 1.54-fold higher than those of BD and BDG populations, respectively. When α-NA, α-NB, and β-NA were used as substrates, males＇ EST activities of JN population were 1.13-, 1.12-, and 1,00-fold and 1.20-, 1.14-, and 1.07-fold higher than those of BD and BDG populations, respectively. The results also showed that the specific activities of the females were higher than those of the males in the BD and JN populations, whereas the specific activities of the males were higher than those of the females in the BDG population. The results of bioassay were consistent with those of biochemical analysis. Thus, it was inferred that the elevated ESTs activities might play an important role in conferring the differences of susceptibility of O. chinensis to malathion in the three collected populations. Enzyme kinetic studies indicated that the Km and Vmax values were different among the three collected populations and between the females and the males. The observed changes in the kinetic parameters might be explained by differential expression patterns of isozymes so that the insect esterases have different affinities and maximum velocities toward the same substrate.

Discovery and Characterization of a Thermostable Esterase from an Oil Reservoir Metagenome

With the aim of identifying novel thermostable esterases, comprehensive sequence databases and cloned fosmid libraries of metagenomes derived from an offshore oil reservoir on the Norwegian Continental Shelf were screened for enzyme candidates using both sequence-and function-based screening. From several candidates identified in both approaches, one enzyme discovered by the functional approach was verified as a novel esterase and subjected to a deeper characterization. The enzyme was successfully over-produced in Escherichia coli and was shown to be thermostable up to 90°C, with the highest esterase activity on short-chain ester substrates and with tolerance to solvents and metal ions. The fact that the thermostable enzyme was solely found by functional screening of the oil reservoir metagenomes illustrates the importance of this approach as a complement to purely sequence-based screening, in which the enzyme candidate was not detected. In addition, this example indicates the large potential of deep-sub-surface oil reservoir metagenomes as a source of novel, thermostable enzymes of potential relevance for industrial applications.

Identification and developmental expression of putative gene encoding juvenile hormone esterase(CpJHE-like) in codling moth, Cydia pomonella(L.)

Juvenile hormone esterase(JHE) is a key enzyme for insects,playing an important role in the regulation of insect growth,development,diapause and reproduction.We identified a complete putative JHE of Cydia pomonella(CpJHE-like) which is comprised of a 1 761 bp coding sequence(CDS) encoding 587 amino acid residues from the transcriptome data.The deduced protein sequence of CpJHE-like showed the highest identity of 60.44% with the Adoxophyes honmai JHE(AhJHE) and the minimal identity of 25.81% with Aedes aegypti JHE(AaJHE).CpJHE-like exhibited all the seven typical motifs of the functional JHEs and had the highly consistent tertiary structure with Manduca sexta JHE(MsJHE).Phylogenetic analysis showed that the CpJHE-like was close to two JHEs from the family Tortricidae.The CpJHE-like transcript level take a leap in the 3-day-old fifth instar larva,increased about 300-fold compared to the basal level.Tissue-specific expression profile showed that the CpJHE-like transcript was expressed mainly in the fat body.This study indicates that the CpJHE-like is the functional JHE,which may play vital roles in the development and reproduction of C.pomonella.

Repellent Activity of Extracts of Wild Rice Species against Panonychus citri and Aphis citricola in Associated with Esterase Isoenzyme in Insests

Six species of wild rice with different ecophenotypes including Oryza grandiglumis （E6-1, E6-3 / 6-4）, O. minuta （E13-9, E13-13）, O. officinalis（E15-8, E15-13）, O. punctata （E16-1, E16-3, E16-13）, O. granulata（E7-4）, and O. latifolia（101392, E9-1, E9-10） were extracted with methnol and the repellent activity of the extracts against the two insects Aphis citricola and Panonychus citri were studied. The extracts of O. officinalis E15-8 showed higher repellent rate to the two insects than those of the other species. The repellent rates of the extracts of E15-8 to P. citriand A. citricola were 83.26% and 87.86% at 5×10^4 μg/mL in 24 h and 87.95% and 82.43% in 48 h, respectively. The extracts of O. officinalis E15-8 had the effect of inhibition to the esterase of the two insects.

Altered acetylcholinesterase levels in the spinal cord anterior horn and dorsal root ganglion following sciatic nerve ischemia

BACKGROUND： Peripheral nerve ischemia has been shown to result in ischemic fiber degenera-tion and axoplasmic transport disturbance. However, the effect on acetylcholinesterase （AChE） ex- pression in relevant cells following sciatic nerve ischemia remains unclear. OBJECTIVE： To observe AChE concentration changes following peripheral nerve ischemia. DESIGN, TIME AND SETTING： The present comparative observation, neuroanatomical experiment was performed at the Central Laboratory Animal of Chengde Medical College between 2006 and 2007. MATERIALS： A total of 20 healthy, adult, Wistar rats were randomized into two groups （n = 10）： 8-day ischemia and 14-day ischemia. METHODS： Ischemia injury was induced in the unilateral sciatic nerve （experimental side） through ligation of the common iliac artery. The contralateral side received no intervention, and served as the control side. Rats in the 8-day ischemia and 14-day ischemia groups were allowed to survive for 8 and 14 days, respectively. MAIN OUTCOME MEASURES： The L5 lumbar spinal cord and the L5 dorsal root ganglion were removed from both sides and sectioned utilizing a Leica vibrating slicer. AChE cellular expression was detected using Karnovsky-Root, and the number of AChE-positive cells and average gray value were analyzed using a MiVnt image analysis system. RESULTS： In the 8-day ischemia group, AChE-positive cell numbers were significantly less in the dorsal root ganglion and spinal cord anterior horn of the experimental side, but the average gray value was significantly greater, compared with the control side （P 〈 0.05）. These changes were more significant in the 14-day ischemia group than in the 8-day ischemia group （P 〈 0.01）. CONCLUSION： Peripheral nerve ischemia leads to decreased AChE expression in the associated cells in a time-dependent manner.

High-throughput Screening of the Enantioselectivity of Hyperthermophilic Mutant Esterases from Archaeon Aeropyrum pernix K1 for Resolution of (R,S)-2-Octanol Acetate

To identify the desired hypertherrnophilic variants within a mutant esterase library for the resolution of （R, S）-2- octanol acetate, a simple, reliable, and versatile method was developed in this study. We built a screening strategy including two steps, first we selected agar plate with substrate to screen the enzymatic activity; secondly we used a pH indicator to screen the enantioselectivity. This method could rapidly detect favorable mutants with high activity and enantioselectivity. A total of 96. 2% of tedious screening work can be precluded using this screening strategy. It is an effective screening for alkyl ester and can be applied to relative screening researches. The four improved mutants were screened from the mutant esterase library. Their enantioselectivities, activities, and structures were investigated at different temperatures.