Title: Esterase D interacts with metallothionein 2A and inhibits the migration of A549 lung cancer cells in vitro Yao W, Chen X, Cui X, Zhou B, Zhao B, Lin Z, Miao J Ref: Journal of Cellular Biochemistry, :, 2023 : PubMed
Esterase D (ESD) is a nonspecific esterase widely distributed in various organisms. ESD plays an important role in regulating cholesterol efflux, inhibiting viral replication and lung cancer growth. MT2A (metallothionein 2A) is the most important isoform of metallothionein (MTs) in human and high expression of MT2A in tumors represents poor prognosis and metastatic behavior. However, there are no reports about the molecular mechanism of ESD in the regulation of tumor metastasis. In this study, we found for the first time that activation ESD promoted its interaction with MT2A and decreased the protein level of MT2A, which resulting in the concentration of free zinc ions up-regulated, and inhibited the migration of A549 lung cancer cells in vitro.
Title: Structure-guided preparation of functional oil rich in 1,3-diacylglycerols and linoleic acid from Camellia oil by combi-lipase Huang C, Lin Z, Zhang Y, Liu Z, Tang X, Li C, Lin L, Huang W, Ye Y Ref: J Sci Food Agric, :, 2022 : PubMed
BACKGROUND: The diacylglycerols (DAG) enriched oil has been attracting attention on nutritional benefits and biological functions, but its various free fatty acids (FFA) composition and unclear relationship between substrate and yield make it difficult to be identified and qualified to produce. In this research, the linoleic acid-enriched diacylglycerols (LA-DAG) was synthesized and enriched from Camellia oil by the esterification process using the combi-lipase Lipozyme TL IM/RM IM systems. RESULTS: The relationship between the FFA compositions and the DAG species productivity was revealed. Results showed that heterogeneous FFA with a major constituent (more than 50%) exhibited higher DAG productivity and inhibited TAG productivity than homogeneous constituents. The joint characterization by HPLC-ELSD, GC-MS and UPLC-HESI-MS/MS identified that DAG components contained dilinoleic acid acyl glyceride, linoleyl-oleyl glyceride, and dioleic acid acyl glyceride in esterification products. Under the optimum conditions, 60.4% 1,3-DAG and 61.3% LA-DAG in the crude product at 1 h reaction were obtained, and further purified to 81.7% LA-DAG and 94.7% DAG by the silica column chromatography. CONCLUSION: This research provides a guideline for identification of DAG species, and a structure-guided preparing method of the DAG enriched oils by the cost-effective combi-lipase. This article is protected by copyright. All rights reserved.
Title: Two cases of Chanarin-Dorfman syndrome with novel and recurrent mutations in the ABHD5 gene Jiang X, Zhong W, Yu B, Lin Z, Wang H Ref: Int J Dermatol, :, 2021 : PubMed
BACKGROUND: Esterase D (ESD) is a nonspecific esterase that detoxifies formaldehyde. Many reports have stated that ESD activity is associated with a variety of physiological and pathological processes. However, the detailed signaling pathway of ESD remains poorly understood. METHODS: Considering the advantages of the small chemical molecule, our recent work demonstrated that 4-chloro-2-(5-phenyl-1-(pyridin-2-yl)-4,5-dihydro-1H-pyrazol-3-yl) phenol (FPD5) activates ESD, and will be a good tool for studying ESD further. Firstly, we determined the interaction between ESD and FK506 binding protein 25 (FKBP25) by yeast two-hybrid assay and co-immunoprecipitation (CO-IP) and analyzed the phosphorylation levels of mTORC1, P70S6K and 4EBP1 by western blot. Furthermore, we used the sulforhodamine B (SRB) and chick chorioallantoic membrane (CAM) assay to analyze cell viability in vitro and in vivo after treatment with ESD activator FPD5. RESULTS: We screened FKBP25 as a candidate protein to interact with ESD by yeast two-hybrid assay. Then we verified the interaction between ESD and endogenous FKBP25 or ectopically expressed GFP-FKBP25 by CO-IP. Moreover, the N-terminus (1-90 aa) domain of FKBP25 served as the crucial element for their interaction. More importantly, ESD reduced the K48-linked poly-ubiquitin chains of FKBP25 and thus stabilized cytoplasmic FKBP25. ESD also promoted FKBP25 to bind more mTORC1, suppressing the activity of mTORC1. In addition, ESD suppressed tumor cell growth in vitro and in vivo through autophagy. CONCLUSIONS: These findings provide novel evidence for elucidating the molecular mechanism of ESD and ubiquitination of FKBP25 to regulate autophagy and cancer cell growth. The ESD/FKBP25/mTORC1 signaling pathway is involved in inhibiting tumor cell growth via regulating autophagy.
Title: A High-Throughput Screening Method for the Directed Evolution of Hydroxynitrile Lyase towards Cyanohydrin Synthesis Zheng YC, Ding LY, Jia Q, Lin Z, Hong R, Yu HL, Xu JH Ref: Chembiochem, 22:996, 2021 : PubMed
Chiral cyanohydrins are useful intermediates in the pharmaceutical and agricultural industries. In nature, hydroxynitrile lyases (HNLs) are a kind of elegant tool for enantioselective hydrocyanation of carbonyl compounds. However, currently available methods for demonstrating hydrocyanation are still stalled at precise, but low-throughput, GC or HPLC analyses. Herein, we report a chromogenic high-throughput screening (HTS) method that is feasible for the cyanohydrin synthesis reaction. This method was highly anti-interference and sensitive, and could be used to directly profile the substrate scope of HNLs either in cell-free extract or fermentation clear broth. This HTS method was also validated by generating new variants of PcHNL5 that presented higher catalytic efficiency and stronger acidic tolerance in variant libraries.
Title: Esterase is a powerful tool for the biodegradation of pyrethroid insecticides Bhatt P, Bhatt K, Huang Y, Lin Z, Chen S Ref: Chemosphere, 244:125507, 2020 : PubMed
Agricultural and household applications of pyrethroid insecticides have significantly increased residual concentrations in living cells and environments. The enhanced concentration is toxic for living beings. Pyrethroid hydrolase enzyme (pyrethroid catalyzing esterase) regulates pyrethroid degradation, and has been well reported in various organisms (bacteria, fungi, insects and animals). Hydrolysis mechanisms of these esterases are different from others and properly function at factors viz., optimum temperature, pH and physicochemical environment. Active site of the enzyme contains common amino acids that play important role in pyrethroid catalysis. Immobilization technology emphasizes the development of better reusable efficiency of pyrethroid hydrolases to carry out large-scale applications for complete degradation of pyrethroids from the environments. In this review we have attempted to provide insights of pyrethroid-degrading esterases in different living systems along with complete mechanisms.
Title: Enhanced Contextual Fear Memory and Elevated Astroglial Glutamate Synthase Activity in Hippocampal CA1 BChE shRNA Knockdown Mice Chen S, Lin Z, Tan KL, Chen R, Su W, Zhao H, Tan Q, Tan W Ref: Front Psychiatry, 11:564843, 2020 : PubMed
Butyrylcholinesterase (BChE) efficiently hydrolyzes acetylcholine (ACh) at high concentrations when acetylcholinesterase (AChE) is substrate-inhibited. Recent studies have shown that BChE also has a function that is independent of ACh, but it has not been fully explored. Low BChE expression is accompanied with higher stress-induced aggression and ghrelin levels in stress models, and BChE knockout mice exhibit cognitive and memory impairments. However, the role of BChE in posttraumatic stress disorder (PTSD) remains unclear. In the present study, we investigated the role of BChE in contextual fear memory and its regulatory effect on the expression of factors related to the glutamate (Glu)-glutamine (Gln) cycle via knockdown studies. We used AAVs and lentiviruses to knockdown BChE expression in the mouse hippocampal CA1 region and C8D1A astrocytes. Our behavioral data from those mice injected with AAV-shBChE in the hippocampal CA1 region showed strengthened fear memory and increased dendritic spine density. Elevated Glu levels and glutamine synthetase (GS) enzyme activity were detected in contextual fear conditioned-BChE knockdown animals and astrocytes. We observed that an AAV-shBChE induced lowering of BChE expression in the hippocampus CA1 region enhanced contextual fear memory expression and promoted the astrocytic Glu-Gln cycle but did not elevate ACh-hydrolyzing activity. This study provides new insight into the regulatory role of BChE in cognition and suggests potential target for stress-related psychiatric disorder such as PTSD where patients experience fear after exposure to severe life-threatening traumatic events.
Title: Degradation of Acephate and Its Intermediate Methamidophos: Mechanisms and Biochemical Pathways Lin Z, Pang S, Zhang W, Mishra S, Bhatt P, Chen S Ref: Front Microbiol, 11:2045, 2020 : PubMed
Acephate is an organophosphate pesticide that has been widely used to control insect pests in agricultural fields for decades. However, its use has been partially restricted in many countries due to its toxic intermediate product methamidophos. Long term exposure to acephate and methamidophos in non-target organisms results in severe poisonous effects, which has raised public concern and demand for the removal of these pollutants from the environment. In this paper, the toxicological effects of acephate and/or methamidophos on aquatic and land animals, including humans are reviewed, as these effects promote the necessity of removing acephate from the environment. Physicochemical degradation mechanisms of acephate and/or methamidophos are explored and explained, such as photo-Fenton, ultraviolet/titanium dioxide (UV/TiO(2)) photocatalysis, and ultrasonic ozonation. Compared with physicochemical methods, the microbial degradation of acephate and methamidophos is emerging as an eco-friendly method that can be used for large-scale treatment. In recent years, microorganisms capable of degrading methamidophos or acephate have been isolated, including Hyphomicrobium sp., Penicillium oxalicum, Luteibacter jiangsuensis, Pseudomonas aeruginosa, and Bacillus subtilis. Enzymes related to acephate and/or methamidophos biodegradation include phosphotriesterase, paraoxonase 1, and carboxylesterase. Furthermore, several genes encoding organophosphorus degrading enzymes have been identified, such as opd, mpd, and ophc2. However, few reviews have focused on the biochemical pathways and molecular mechanisms of acephate and methamidophos. In this review, the mechanisms and degradation pathways of acephate and methamidophos are summarized in order to provide a new way of thinking for the study of the degradation of acephate and methamidophos.
Title: AChR myasthenia gravis switching to MuSK or double antibody positive myasthenia gravis in two children and literature review Lu Y, Ran H, Yang W, Ma Q, Qiu L, Ou C, Chen P, Lin Z, Liu W Ref: Neuromuscular Disorders, :, 2020 : PubMed
Muscle-specific tyrosine kinase antibody (MuSK-Ab) and acetylcholine receptor antibody (AChR-Ab) coexistence in myasthenia gravis (MG) is very rare. In this report, two children with AChR-Ab switching to double antibody positive MG (DP-MG) or MuSK-Ab positive MG (MuSK-MG) are described. Six similar cases were found in the literature via online database search. Therefore, this study describes eight patients in total, six female and two male. The average age of onset was 7.25 +/- 5.95 years. Four AChR-MG patients switched to DP-MG with no known precipitating factor and four switched after thymectomy (two to MuSK-MG and two to DP-MG). After the serological switch, the patients transitioned to the phenotype of MuSK-MG and responded poorly to cholinesterase inhibitors and well to corticosteroids and plasma exchange.
Carbofuran is one of the most toxic broad-spectrum and systemic N-methyl carbamate pesticide, which is extensively applied as insecticide, nematicide and acaricide for agricultural, domestic and industrial purposes. It is extremely lethal to mammals, birds, fish and wildlife due to its anticholinesterase activity, which inhibits acetyl-cholinesterase and butyrylcholinesterse activity. In humans, carbofuran is associated with endocrine disrupting activity, reproductive disorders, cytotoxic and genotoxic abnormalities. Therefore, cleanup of carbofuran-contaminated environments is of utmost concern and urgently needs an adequate, advanced and effective remedial technology. Microbial technology (bacterial, fugal and algal species) is a very potent, pragmatic and ecofriendly approach for the removal of carbofuran. Microbial enzymes and their catabolic genes exhibit an exceptional potential for bioremediation strategies. To understand the specific mechanism of carbofuran degradation and involvement of carbofuran hydrolase enzymes and genes, highly efficient genomic approaches are required to provide reliable information and unfold metabolic pathways. This review briefly discusses the carbofuran toxicity and its toxicological impact into the environment, in-depth understanding of carbofuran degradation mechanism with microbial strains, metabolic pathways, molecular mechanisms and genetic basis involved in degradation.
Title: New insights into the microbial degradation and catalytic mechanism of synthetic pyrethroids Zhan H, Huang Y, Lin Z, Bhatt P, Chen S Ref: Environ Research, 182:109138, 2020 : PubMed
The significant applications of pyrethroid insecticides in agro-ecosystem and household environments have raised serious environmental concerns. Environmental bioremediation has emerged as an effective and eco-friendly approach to remove or neutralize hazardous compounds. Bioaugmentation accelerates pyrethroid degradation in liquid cultures and soil. Pyrethroid-degrading microorganisms have been extensively studied to cope with pyrethroid residues. Microorganisms primarily hydrolyze the ester bonds of pyrethroids, and their degradation pathways have been elaborated. The functional genes and enzymes involved in microbial degradation have also been screened and studied. Carboxylesterase plays a key role in pyrethroid degradation by cleaving its carboxylester linkage. The catalytic mechanism is dependent on a specific catalytic triad, consisting of three amino acid residues (glutamine, histidine, and serine) within the active site of the carboxylesterase enzyme. Pyrethroid-degrading strains and enzymes have proven to be effective for the bioremediation of pyrethroid-contaminated environments. In this review, we have summarized newly isolated pyrethroid-degrading strains and proposed the degradation pathways along with key functional genes/enzymes. To develop an efficient bioremediation strategy, pyrethroid-degrading microorganisms should be comprehensively explored.
A recent phase 1 trial of the fatty acid amide hydrolase (FAAH) inhibitor BIA 10-2474 led to the death of one volunteer and produced mild-to-severe neurological symptoms in four others. Although the cause of the clinical neurotoxicity is unknown, it has been postulated, given the clinical safety profile of other tested FAAH inhibitors, that off-target activities of BIA 10-2474 may have played a role. Here we use activity-based proteomic methods to determine the protein interaction landscape of BIA 10-2474 in human cells and tissues. This analysis revealed that the drug inhibits several lipases that are not targeted by PF04457845, a highly selective and clinically tested FAAH inhibitor. BIA 10-2474, but not PF04457845, produced substantial alterations in lipid networks in human cortical neurons, suggesting that promiscuous lipase inhibitors have the potential to cause metabolic dysregulation in the nervous system.
The high-affinity choline transporter (CHT) is the rate-limiting determinant of acetylcholine (ACh) synthesis, yet the transporter remains a largely undeveloped target for the detection and manipulation of synaptic cholinergic signaling. To expand CHT pharmacology, we pursued a high-throughput screen for novel CHT-targeted small molecules based on the electrogenic properties of transporter-mediated choline transport. In this effort, we identified five novel, structural classes of CHT-specific inhibitors. Chemical diversification and functional analysis of one of these classes identified ML352 as a high-affinity (Ki = 92 nM) and selective CHT inhibitor. At concentrations that fully antagonized CHT in transfected cells and nerve terminal preparations, ML352 exhibited no inhibition of acetylcholinesterase (AChE) or cholineacetyltransferase (ChAT) and also lacked activity at dopamine, serotonin, and norepinephrine transporters, as well as many receptors and ion channels. ML352 exhibited noncompetitive choline uptake inhibition in intact cells and synaptosomes and reduced the apparent density of hemicholinium-3 (HC-3) binding sites in membrane assays, suggesting allosteric transporter interactions. Pharmacokinetic studies revealed limited in vitro metabolism and significant CNS penetration, with features predicting rapid clearance. ML352 represents a novel, potent, and specific tool for the manipulation of CHT, providing a possible platform for the development of cholinergic imaging and therapeutic agents.
Title: Optimization of Fermentation Medium for Extracellular Lipase Production from Aspergillus niger Using Response Surface Methodology Jia J, Yang X, Wu Z, Zhang Q, Lin Z, Guo H, Lin CS, Wang J, Wang Y Ref: Biomed Res Int, 2015:497462, 2015 : PubMed
Lipase produced by Aspergillus niger is widely used in various industries. In this study, extracellular lipase production from an industrial producing strain of A. niger was improved by medium optimization. The secondary carbon source, nitrogen source, and lipid were found to be the three most influential factors for lipase production by single-factor experiments. According to the statistical approach, the optimum values of three most influential parameters were determined: 10.5 g/L corn starch, 35.4 g/L soybean meal, and 10.9 g/L soybean oil. Using this optimum medium, the best lipase activity was obtained at 2,171 U/mL, which was 16.4% higher than using the initial medium. All these results confirmed the validity of the model. Furthermore, results of the Box-Behnken Design and quadratic models analysis indicated that the carbon to nitrogen (C/N) ratio significantly influenced the enzyme production, which also suggested that more attention should be paid to the C/N ratio for the optimization of enzyme production.
Title: Impact of epoxide hydrolase 1 polymorphisms on lung cancer susceptibility in asian populations Yu W, Lin Z, Qu B Ref: Cell Biochem Biophys, 71:813, 2015 : PubMed
Inconsistent association of microsomal epoxide hydrolase (mEH) polymorphisms (Tyr113His, His139Arg) and lung cancer susceptibility have been reported in earlier studies. This study was undertaken to assess if mEH Tyr113His and His139Arg represent risk factors for lung cancer in Asian population. We exhaustively searched multiple databases to identify all eligible studies. Odds ratios were calculated to estimate the strength of genetic associations. This meta-analysis finally combined 2,522 subjects for Tyr113His and 2,725 subjects for His139Arg. In the analysis of Tyr113His, the His/His genotype carriers were found to have 29 % higher risk of lung cancer compared to the Tyr/Tyr carriers (His/His vs. Tyr/Tyr, odds ratio, 1.29, 95 % confidence interval, 1.06-1.58). A significantly increased risk was also seen in His/His versus His/Tyr + Tyr/Tyr (odds ratio, 1.29, 95 % confidence interval, 1.07-1.55). Likewise, His139Arg demonstrated a significant association with lung cancer (Arg/His vs. His/His, odds ratio, 1.2 6, 95 % confidence interval, 1.06-1.49; odds ratio, 1.24, 95 % confidence interval, 1.05-1.46). Stratified analysis by ethnicity showed both of the polymorphisms were associated with lung cancer in Chinese populations. These results suggest that the genetic associations exist between mEH polymorphisms and lung cancer susceptibility in Asian populations.
Title: Marsupellins A-F, ent-longipinane-type sesquiterpenoids from the Chinese liverwort Marsupella alpine with acetylcholinesterase inhibitory activity Zhang J, Fan P, Zhu R, Li R, Lin Z, Sun B, Zhang C, Zhou J, Lou H Ref: Journal of Natural Products, 77:1031, 2014 : PubMed
Acetylcholinesterase (AChE) inhibitory activity-guided fractionation of the Chinese liverwort Marsupella alpine afforded six new [marsupellins A-F (1-6)] and three known (7-9) ent-longipinane-type sesquiterpenoids. The structures were determined from MS and NMR spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Compounds 1-9 exhibited moderate to weak AChE inhibitory activity.
Ferrets have become an indispensable tool in the understanding of influenza virus virulence and pathogenesis. Furthermore, ferrets are the preferred preclinical model for influenza vaccine and therapeutic testing. Here we characterized the influenza infectome during the different stages of the infectious process in ferrets with and without prior specific immunity to influenza. RNA from lung tissue and lymph nodes from infected and naive animals was subjected to next-generation sequencing, followed by de novo data assembly and annotation of the resulting sequences; this process generated a library comprising 13,202 ferret mRNAs. Gene expression profiles during pandemic H1N1 (pdmH1N1) influenza virus infection were analyzed by digital gene expression and solid support microarrays. As expected during primary infection, innate immune responses were triggered in the lung tissue; meanwhile, in the lymphoid tissue, genes encoding antigen presentation and maturation of effector cells of adaptive immunity increased dramatically. After 5 days postinfection, the innate immune gene expression was replaced by the adaptive immune response, which correlates with viral clearance. Reinfection with homologous pandemic influenza virus resulted in a diminished innate immune response, early adaptive immune gene regulation, and a reduction in clinical severity. The fully annotated ferret infectome will be a critical aid to the understanding of the molecular events that regulate disease severity and host-influenza virus interactions among seasonal, pandemic, and highly pathogenic avian influenzas.
Lactobacillus shenzhenensis strain LY-73(T) is a novel species which was first isolated from fermented goods. Here, we report the draft genome sequence of Lactobacillus shenzhenensis LY-73(T).
Carboxylesterases provide key mechanisms of resistance to insecticides, particularly organophosphates (OPs), in insects. One resistance mechanism is a qualitative change in the properties of a carboxylesterase. Two mutant forms, G151D and W271L, have been observed, mostly in dipteran species, to affect substrate specificity of enzymes. But whether these two single mutations can commonly change character of insect carboxylesterases is unknown. In our study carboxylesterase genes from seven insects distributed among four orders were cloned, mutated at position 151 or 271 and expressed in Escherichia coli. The kinetics of the purified recombinant proteins was examined towards an artificial carboxylester and two OP insecticides. The G/A151D and W271L mutation significantly reduced carboxylesterase activity in 87.5% and 100% cases, respectively, and at the same time conferred OP hydrolase activities in 62.5% and 87.5% cases, respectively. Thus, the change at position 271 is more effective to influence substrate specificity than that at position 151. These results may suggest that these two mutations have the potential to cause insecticide resistance broadly in insects.
BACKGROUND: The association between -250G>A polymorphism in the promoter region of the hepatic lipase gene (LIPC) and plasma high-density lipoprotein cholesterol (HDL-C) concentration is contradictory in diverse ethnics. Bai Ku Yao is an isolated subgroup of the Yao minority in China. This study was designed to detect the association of LIPC -250G>A (rs2070895) polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations. METHODS: A total of 778 subjects of Bai Ku Yao and 648 participants of Han Chinese aged 15-80 were randomly selected from our previous stratified randomized cluster samples. Genotyping of the LIPC -250G>A was performed by polymerse chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. RESULTS: The levels of serum total cholesterol (TC), HDL-C, low-density lipoprotein cholesterol (LDL-C) and apolipoprotein (Apo) AI were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequencies of GG, GA and AA genotypes were 50.0%, 43.3% and 6.7% in Bai Ku Yao, and 35.7%, 50.6% and 13.7% in Han (P < 0.01); respectively. The frequencies of G and A alleles were 71.7% and 28.3% in Bai Ku Yao, and 61.0% and 39.0% in Han (P < 0.01). The levels of HDL-C and the ratio of ApoAI to ApoB in Bai Ku Yao were lower in GG genotype than in GA or AA genotype (P < 0.05-0.01). The levels of TC, HDL-C, LDL-C and ApoB in Han were lower in GG genotype than in GA or AA genotype (P < 0.05-0.01). The levels of HDL-C and the ratio of ApoAI to ApoB in Bai Ku Yao, and the levels of HDL-C, LDL-C and ApoB in Han were correlated with genotype and/or allele (P < 0.05 for all). Serum lipid parameters were also correlated with age, sex, alcohol consumption, cigarette smoking, blood pressure, body weight, and body mass index in both ethnic groups. CONCLUSIONS: The differences in the serum lipid profiles between the two ethnic groups might partly result from different genotypic frequency of LIPC -250G>A or different LIPC-enviromental interactions.
Title: Morphing activity between structurally similar enzymes: from heme-free bromoperoxidase to lipase Chen B, Cai Z, Wu W, Huang Y, Pleiss J, Lin Z Ref: Biochemistry, 48:11496, 2009 : PubMed
In this study, to explore the plasticity of the alpha/beta-hydrolase fold family, we converted bromoperoxidase A2 (BPO-A2) from Streptomyces aureofaciens to a lipase by structure comparison with lipase A (LipA) from Bacillus subtilis. These two enzymes have similar structures (2.1 A rmsd) and a very low level of sequence identity ( approximately 18%). A variant BL1 was constructed by deleting the caplike domain of BPO-A2 and further fine-tuning the newly formed substrate binding site. The lipase activity was successfully transplanted on BL1, while the halogenation activity was totally lost. BL1 also showed higher hydrolytic activities toward long chain p-nitrophenyl esters, such as p-nitrophenyl caprylate (3.7-fold) and p-nitrophenyl palmitate (7.0-fold), while its activity toward a short chain ester (p-nitrophenyl acetate) decreased dramatically, to only 1.2% of that of BPO-A2. After two rounds of directed evolution and site-directed mutagenesis on selected residues, several mutants with both improved hydrolytic activities and substrate preferences toward long chain substrates were obtained. The highest hydrolytic activity toward p-nitrophenyl palmitate of the best mutant BL1-2-E8-plusI was improved by 40-fold compared with that of BL1. These results demonstrate the possibility of manipulating the caplike domain of alpha/beta-hydrolase fold enzymes and provide further understanding of the structure-function relationship of the alpha/beta-hydrolase fold enzymes. The design strategy used in this study could serve as a useful approach for constructing variants with targeted catalytic properties using the alpha/beta-hydrolase fold.
Title: [Therapeutic efficacy of N6-cyclopentyladenosine against acute dichlorvos poisoning] Zhu QH, Huang JX, Lin Z Ref: Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi, 23:94, 2005 : PubMed
OBJECTIVE: To study the therapeutic efficacy and mechanism of adenosine receptor agonist N(6)-cyclopentyladenosine (CPA) against acute dichlorvos poisoning. METHODS: Soon after a certain doses of dichlorvos were given to mice and rats by gastrogavage, physiological saline, CPA, atropine or pralidoxime chloride were administered to different groups. Toxic signs and survival rate were recorded and cholinesterase (ChE) activities and acetylcholine (ACh) concentrations in whole blood were determined in treatment group with CPA and non-treatment group after dichlorvos was given to rats by gastrogavage. RESULTS: (1) The alleviated and delayed appearance of toxic signs as well as obvious prolongation of survival time was observed in CPA treatment group compared with non-treatment group. (2) ChE activities in both treatment group with CPA [(0.49 +/- 0.05) U/ml] and non-treatment group [(0.52 +/- 0.04) U/ml] were significantly lower than that [(1.56 +/- 0.15) U/ml] of the control group (P < 0.01), but there was no significant difference between treatment group and non-treatment group (P > 0.05). (3) ACh concentration [(204.24 +/- 20.48) microg/ml] in whole blood of treatment group with CPA was significantly lower than that [(230.91 +/- 25.61) microg/ml] of non-treatment group (P < 0.05). CONCLUSION: CPA has therapeutic efficacy against acute dichlorvos poisoning, which is probably through the decrease in ACh concentration.
