Title: Ovalbumin-coated gold nanoparticles with interesting colloidal stability for colorimetric detection of carbaryl in complex media Hao H, Zhu J, Yang B, Peng L, Lou S Ref: Food Chem, 403:134485, 2023 : PubMed
Pesticide carbaryl can cause serious environmental pollution and its sensitive detection is of increasing interest. Gold nanoparticles (AuNPs) are classically colorimetric probes for detection of many analytes, but the instability in complex media limits their application. Here, Au@Ova NPs have been developed as a stable, effective, sensitive, and selective sensing system for colorimetric detection of carbaryl. Au@Ova NPs present unique and proper colloidal stability in various medias containing salt, small molecules, organic solvent (DMSO), and seawater, which are distinct from previous ones including citrate (or rhodamine B) capped AuNPs. Compared with Au@BSA NPs, Au@Ova NPs showed efficient responses to carbaryl by inhibiting acetylcholinesterase, with a linear concentration range between 0 and 25 g/L and a detection limit of 0.25 g/L. In addition, this nanoprobe also has good selectivity and can be applied in different real samples analysis, including fruit juice (tomato and apple) and real water samples (artificial urine and seawater).
Epoxyeicosatrienoic acids (EETs) have pleiotropic endogenous cardiovascular protective effects and can be hydrolyzed to the corresponding dihydroxyeicosatrienoic acids by soluble epoxide hydrolase (sEH). Heart failure with preserved ejection fraction (HFpEF) has shown an increased prevalence and worse prognosis over the decades. However, the role of sEH activity in HFpEF remains unclear. We enrolled 500 patients with HFpEF and 500 healthy controls between February 2010 and March 2016. Eight types of sEH-related eicosanoids were measured according to target metabolomics, and their correlation with clinical endpoints was also analyzed. The primary endpoint was cardiac mortality, and the secondary endpoint was a composite of cardiac events, including heart failure (HF) readmission, cardiogenic hospitalization, and all-cause mortality. Furthermore, the effect of sEH inhibitors on cardiac diastolic function in HFpEF was investigated in vivo and in vitro. Patients with HFpEF showed significantly enhanced EET degradation by the sEH enzyme compared with healthy controls. More importantly, sEH activity was positively correlated with cardiac mortality in patients with HFpEF, especially in older patients with arrhythmia. A consistent result was obtained in the multiple adjusted models. Decreased sEH activity by the sEH inhibitor showed a significant effective effect on the improvement of cardiac diastolic function by ameliorating lipid disorders in cardiomyocytes of HFpEF mouse model. This study demonstrated that increased sEH activity was associated with cardiac mortality in patients with HFpEF and suggested that sEH inhibition could be a promising therapeutic strategy to improve diastolic cardiac function. Clinical trial identifier: NCT03461107 (https://clinicaltrials.gov). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s43657-022-00069-8.
Title: A green photocatalytic-biosensor for colorimetric detection of pesticide (carbaryl) based on inhibition of acetylcholinesterase Peng L, Zhu J, Yang B, Hao H, Lou S Ref: Talanta, 246:123525, 2022 : PubMed
Carbaryl is a widely-used carbamate pesticide and the detection of its residues in environmental, food and clinical samples is of great importance. In this sturdy, we developed a green photocatalytic-biosensor based on double strand DNA-SYBR green I complex for sensitively colorimetric detection of carbaryl. This green photocatalytic-biosensor can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) into blue ox-TMB. Meanwhile thiocholine is catalytically produced by acetylcholinesterase (AChE) to directly reduce blue ox-TMB into colorless TMB. But the activity of AChE will be suppressed by carbaryl, thus generating less thiocholine and resulting in more ox-TMB for colorimetric analysis. After the careful optimization of sensing conditions (2 microM for DNA concentration, 50 x concentration for SYBR Green I, 10 min for illumination time), the lowest detectable concentration for carbaryl is 0.008 ng/mL with a linear response in the range of 0.01-0.25 ng/mL. In addition, this photocatalytic-biosensor has good selectivity over non-target chemicals (acetamiprid, atrazine, carbendazim, melamine, bisphenol A, estradiol). It also allows detection of pesticides in real samples verified by a standard HPLC method.
Title: Transcriptomic responses of the zearalenone (ZEN)-detoxifying yeast Apiotrichum mycotoxinivorans to ZEN exposure Yang ZK, Li DW, Peng L, Liu CF, Wang ZY Ref: Ecotoxicology & Environmental Safety, 241:113756, 2022 : PubMed
Zearalenone (ZEN) is a potent oestrogenic mycotoxin that is mainly produced by Fusarium species and is a serious environmental pollutant in animal feeds. Apiotrichum mycotoxinivorans has been widely used as a feed additive to detoxify ZEN. However, the effects of ZEN on A. mycotoxinivorans and its detoxification mechanisms remain unclear. In this study, transcriptomic and bioinformatic analyses were used to investigate the molecular responses of A. mycotoxinivorans to ZEN exposure and the genetic basis of ZEN detoxification. We detected 1424 significantly differentially expressed genes (DEGs), of which 446 were upregulated and 978 were downregulated. Functional and enrichment analyses showed that ZEN-induced genes were significantly associated with xenobiotic metabolism, oxidative stress response, and active transport systems. However, ZEN-inhibited genes were mainly related to cell division, cell cycle, and fungal development. Subsequently, bioinformatic analysis identified candidate ZEN-detoxification enzymes. The Baeyer-Villiger monooxygenases and carboxylesterases, which are responsible for the formation and subsequent hydrolysis of a new ZEN lactone, respectively, were significantly upregulated. In addition, the expression levels of genes related to conjugation and transport involved in the xenobiotic detoxification pathway were significantly upregulated. Moreover, the expression levels of genes encoding enzymatic antioxidants and those related to growth and apoptosis were significantly upregulated and downregulated, respectively, which made it possible for A. mycotoxinivorans to survive in a highly toxic environment and efficiently detoxify ZEN. This is the first systematic report of ZEN tolerance and detoxification in A. mycotoxinivorans. We identified the metabolic enzymes that were potentially involved in detoxifying ZEN in the GMU1709 strain and found that ZEN-induced transcriptional regulation of genes is key to withstanding highly toxic environments. Hence, our results provide valuable information for developing enzymatic detoxification systems or engineering this detoxification pathway in other species.
Title: Current anti-Alzheimer's disease effect of natural products and their principal targets Zhu Y, Peng L, Hu J, Chen Y, Chen F Ref: J Integr Neurosci, 18:327, 2019 : PubMed
Various bioactive substances isolated from natural products play a pivotal role in the prevention and cure of neurodegenerative diseases, such as Alzheimer's disease. Currently, there are many theories about the pathogenesis of this disease. In this review we discuss among them, the cholinergic hypotheses, the Abeta toxicity hypothesis, and the tau dysfunction hypothesis. Multiple potential targets are a focus for the development of anti-AD drugs. There is an urgent need to develop more effective therapies to treat and delay the onset of the disease and to find safe and effective drugs. In this review, the recent progress of anti-AD effects and their principal targets are updated.
Broomcorn millet (Panicum miliaceum L.) is the most water-efficient cereal and one of the earliest domesticated plants. Here we report its high-quality, chromosome-scale genome assembly using a combination of short-read sequencing, single-molecule real-time sequencing, Hi-C, and a high-density genetic map. Phylogenetic analyses reveal two sets of homologous chromosomes that may have merged ~5.6 million years ago, both of which exhibit strong synteny with other grass species. Broomcorn millet contains 55,930 protein-coding genes and 339 microRNA genes. We find Paniceae-specific expansion in several subfamilies of the BTB (broad complex/tramtrack/bric-a-brac) subunit of ubiquitin E3 ligases, suggesting enhanced regulation of protein dynamics may have contributed to the evolution of broomcorn millet. In addition, we identify the coexistence of all three C4 subtypes of carbon fixation candidate genes. The genome sequence is a valuable resource for breeders and will provide the foundation for studying the exceptional stress tolerance as well as C4 biology.
Title: Three MOF-Templated Carbon Nanocomposites for Potential Platforms of Enzyme Immobilization with Improved Electrochemical Performance Dong S, Peng L, Wei W, Huang T Ref: ACS Appl Mater Interfaces, 10:14665, 2018 : PubMed
An efficient and facile metal-organic framework (MOF)-template strategy for preparing carbon nanocomposites has been developed. First of all, a series of metal ions, including Fe(3+), Zr(4+), and La(3+), were respectively connected with 2-aminoterephthalate (H2ATA) to form three metal-organic frameworks (MOFs) and then three novel MOF-derived materials were obtained by annealing them at 550 degrees C under N2 atmosphere. The morphologies and microstructure results showed that they still retained the original structure of MOFs and formed carbon-supported metal oxide hybrid nanomaterials. Interestingly, it was found that La-MOF-NH2 and its derived materials were first reported, which had wool-ball-like structure formed by many streaky-shaped particles intertwining each other. Furthermore, these MOF-derived materials were all successfully used as effective immobilization matrixes of acetylcholinesterase (AChE) to construct biosensors for the detection of methyl parathion. Especially, [La-MOF-NH2]N2 with wool-ball-like structure not only provided more active sites of multicontents to increase AChE immobilization amount but also facilitated the accessibility of electron transfer and shorten their diffusion length on the surface of electrode. Under optimal conditions, the biosensor based on [La-MOF-NH2]N2 displayed the widest linear range of 1.0 x 10(-13)-5.0 x 10(-9) g mL(-1) and the lowest detection limit of 5.8 x 10(-14) g mL(-1) in three biosensors. This study illustrates the feasibility and the potential of a series of MOF-derived materials for biosensors with improved electrochemical performance.
The tobacco cutworm, Spodoptera litura, is among the most widespread and destructive agricultural pests, feeding on over 100 crops throughout tropical and subtropical Asia. By genome sequencing, physical mapping and transcriptome analysis, we found that the gene families encoding receptors for bitter or toxic substances and detoxification enzymes, such as cytochrome P450, carboxylesterase and glutathione-S-transferase, were massively expanded in this polyphagous species, enabling its extraordinary ability to detect and detoxify many plant secondary compounds. Larval exposure to insecticidal toxins induced expression of detoxification genes, and knockdown of representative genes using short interfering RNA (siRNA) reduced larval survival, consistent with their contribution to the insect's natural pesticide tolerance. A population genetics study indicated that this species expanded throughout southeast Asia by migrating along a South India-South China-Japan axis, adapting to wide-ranging ecological conditions with diverse host plants and insecticides, surviving and adapting with the aid of its expanded detoxification systems. The findings of this study will enable the development of new pest management strategies for the control of major agricultural pests such as S. litura.
Title: Synthesis of reticulated hollow spheres structure NiCo2S4 and its application in organophosphate pesticides biosensor Peng L, Dong S, Wei W, Yuan X, Huang T Ref: Biosensors & Bioelectronics, 92:563, 2017 : PubMed
Electrode materials play a key role in the development of electrochemical sensors, particularly enzyme-based biosensors. Here, a novel NiCo2S4 with reticulated hollow spheres assembled from rod-like structures was prepared by a one-pot solvothermal method and its formation mechanism was discussed. Moreover, comparison of NiCo2S4 materials from different experiment conditions as biosensors was investigated by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV), and the best one that was reticulated hollow spheres assembled from rod-like structures NiCo2S4 has been successfully employed as a matrix of AChE immobilization for the special structure, superior conductivity and rich reaction active sites. When using common two kinds of organophosphate pesticides (OPs) as model analyte, the biosensors demonstrated a wide linear range of 1.0x10-12-1.0x10-8gmL-1 with the detection limit of 4.2x10-13gmL-1 for methyl parathion, and 1.0x10-13-1.0x10-10gmL-1 with the detection limit of 3.5x10-14gmL-1 for paraoxon, respectively. The proposed biosensors exhibited many advantages such as acceptable stability and low cost, providing a promising tool for analysis of OPs.
Title: Rational Design of a Red-Emissive Fluorophore with AIE and ESIPT Characteristics and Its Application in Light-Up Sensing of Esterase Peng L, Xu S, Zheng X, Cheng X, Zhang R, Liu J, Liu B, Tong A Ref: Analytical Chemistry, 89:3162, 2017 : PubMed
The development of red fluorophores with efficient solid-state emission is still challenging. Herein, a red fluorophore 1 with aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics is rationally designed and facilely synthesized by attaching an electron-donor diethylamine and an electron-acceptor maleonitrile group to salicyladazine. In contrast to many red fluorophores which undergo serious aggregation-caused quenching (ACQ), compound 1 emits bright red fluorescence (lambdaem = 650 nm, PhiF = 24.3%) in the solid state with a large Stokes shift of 174 nm. Interestingly, control compounds 2 and 3, which have similar structures as 1, exhibit obvious aggregation-caused quenching (ACQ) characteristics. The difference in the crystal structures of 1, 2, and 3 reveals that the interplanar spacing among molecules plays a decisive role in realizing the AIE characteristics of 1. Moreover, when the hydroxyl group of 1 was substituted by an esterase reactive acetoxyl, a fluorescence light-up probe 4 was developed for sensing of esterase based on the selective reaction between 4 and esterase to generate the AIE and ESIPT active molecule 1. The linear range for in vitro quantification of esterase is 0.01-0.15 U/mL with a detection limit of 0.005 U/mL. Probe 4 was also successfully applied to image esterase in mitochondria of living cells.
Title: A novel assay to determine acetylcholinesterase activity: The application potential for screening of drugs against Alzheimer's disease Peng L, Rong Z, Wang H, Shao B, Kang L, Qi H, Chen H Ref: Biomedical Chromatography, 31:, 2017 : PubMed
Acetycholinesterase (AChE) that regulates hydrolysis of acetylcholine (ACh) in the brain, is an important target for treatment of Alzheimer's disease (AD), a feature of which is ACh deficiency. However, the methods to precisely determine AChE activity are still under development. We developed a new method to exploit acetylcholine-d4 as a surrogate substrate of ACh and measure product choline-d4 via liquid chromatography-tandem mass spectrometry (LC-MS/MS). This assay detected activity of AChE present in the normal mouse brain, which is consistent with the standard Ellman assay that determines products spectrophotometrically. In AD mouse models, the result of LC-MS/MS assay showed significant higher AChE activity than that seen in control normal mice, while treatment of AD mice with an AChE inhibitor, huperzine A, led to partial decreases in AChE activity. Our results suggest that this surrogate-based LC-MS/MS method is a new, sensitive and convenient assay for the determination of AChE activity, providing a useful means for screening active compounds that target AChE.
Title: Role of farnesoid X receptor in establishment of ontogeny of phase-I drug metabolizing enzyme genes in mouse liver Peng L, Piekos S, Guo GL, Zhong XB Ref: Acta Pharm Sin B, 6:453, 2016 : PubMed
The expression of phase-I drug metabolizing enzymes in liver changes dramatically during postnatal liver maturation. Farnesoid X receptor (FXR) is critical for bile acid and lipid homeostasis in liver. However, the role of FXR in regulating ontogeny of phase-I drug metabolizing genes is not clear. Hence, we applied RNA-sequencing to quantify the developmental expression of phase-I genes in both Fxr-null and control (C57BL/6) mouse livers during development. Liver samples of male C57BL/6 and Fxr-null mice at 6 different ages from prenatal to adult were used. The Fxr-null showed an overall effect to diminish the "day-1 surge" of phase-I gene expression, including cytochrome P450s at neonatal ages. Among the 185 phase-I genes from 12 different families, 136 were expressed, and differential expression during development occurred in genes from all 12 phase-I families, including hydrolysis: carboxylesterase (Ces), paraoxonase (Pon), and epoxide hydrolase (Ephx); reduction: aldoketo reductase (Akr), quinone oxidoreductase (Nqo), and dihydropyrimidine dehydrogenase (Dpyd); and oxidation: alcohol dehydrogenase (Adh), aldehyde dehydrogenase (Aldh), flavin monooxygenases (Fmo), molybdenum hydroxylase (Aox and Xdh), cytochrome P450 (P450), and cytochrome P450 oxidoreductase (Por). The data also suggested new phase-I genes potentially targeted by FXR. These results revealed an important role of FXR in regulation of ontogeny of phase-I genes.
Title: Lipase-catalyzed hydrolysis of linseed oil: optimization using response surface methodology Chen W, Sun S, Liang S, Peng L, Wang Y, Shen M Ref: J Oleo Sci, 63:619, 2014 : PubMed
Lipase-catalyzed hydrolysis of linseed oil was investigated. Four commercially available microbial lipases of Lipase AY, Lipozyme RMIM, Lipozyme TLIM, and Novozym 435 were used. Among these tested lipases, Lipase AY exhibited the best hydrolysis effeciency to linseed oil. The effect of reaction variables was also evaluated and optimized using response surface methodology. A second-order regression for the Box-Behken design was used to study the effect of five independent variables, such as, temperature, pH, oil-aqueous phase ratio, enzyme load, and reaction time, on the hydrolysis of linseed oil. The optimal conditions were as follows: temperature 33 degC, pH 5.80, oil-aqueous phase ratio 0.90 (w/w), enzyme load 1.20% (relative to the weight of total substrates), and reaction time 3.33 h. Under these conditions, the hydrolysis ratio of linseed oil was 93.92+/-0.54%.
Strigolactones (SLs) are a novel class of plant hormones that inhibit shoot branching. Currently, two proteins in rice are thought to play crucial roles in SL signal transduction. DWARF14 (D14), an alpha/beta hydrolase, is responsible for SL perception, while DWARF3 (D3), an F-box protein with leucine-rich repeats, is essential for SL signal transduction. However, how these two proteins transmit SL signals to downstream factors remains unclear. Here, we characterized a high-tillering dwarf rice mutant, gsor300097, which is insensitive to GR24, a synthetic analog of SL. Mapping and sequencing analysis showed that gsor300097 is a novel allelic mutant of D3, in which a nonsense mutation truncates the protein from 720 to 527 amino acids. The D3 gene was strongly expressed in root, leaf, shoot base and panicle. Nuclear-localized F-box protein D3 played a role in the SCF complex by interacting with OSK1, OSK5 or OSK20 and OsCullin1. In addition, D3 associated with D14 in a GR24-dependent manner in vivo. Taken together, our findings suggested that D3 assembled into an SCF(D3) complex and associated with D14 to suppress rice shoot branching.
BACKGROUND & AIMS: Hepatitis C virus (HCV) infection is a leading cause of end-stage liver disease. Interferon-alpha (IFNalpha) is an important component of anti-HCV therapy; it up-regulates transcription of IFN-stimulated genes, many of which have been investigated for their antiviral effects. However, all of the genes required for the antiviral function of IFNalpha (IFN effector genes [IEGs]) are not known. IEGs include not only IFN-stimulated genes, but other nontranscriptionally induced genes that are required for the antiviral effect of IFNalpha. In contrast to candidate approaches based on analyses of messenger RNA (mRNA) expression, identification of IEGs requires a broad functional approach. METHODS: We performed an unbiased genome-wide small interfering RNA screen to identify IEGs that inhibit HCV. Huh7.5.1 hepatoma cells were transfected with small interfering RNAs incubated with IFNalpha and then infected with JFH1 HCV. Cells were stained using HCV core antibody, imaged, and analyzed to determine the percent infection. Candidate IEGs detected in the screen were validated and analyzed further. RESULTS: The screen identified 120 previously unreported IEGs. From these, we more fully evaluated the following: asparagine-linked glycosylation 10 homolog (yeast, alpha-1,2-glucosyltransferase); butyrylcholinesterase; dipeptidyl-peptidase 4 (CD26, adenosine deaminase complexing protein 2); glucokinase (hexokinase 4) regulator; guanylate cyclase 1, soluble, beta 3; MYST histone acetyltransferase 1; protein phosphatase 3 (formerly 2B), catalytic subunit, beta isoform; peroxisomal proliferator-activated receptor-gamma-DBD-interacting protein 1; and solute carrier family 27 (fatty acid transporter), member 2; and demonstrated that they enabled IFNalpha-mediated suppression of HCV at multiple steps of its life cycle. Expression of these genes had more potent effects against flaviviridae because a subset was required for IFNalpha to suppress dengue virus but not influenza A virus. In addition, many of the host genes detected in this screen (92%) were not transcriptionally stimulated by IFNalpha; these genes represent a heretofore unknown class of non-IFN-stimulated gene IEGs. CONCLUSIONS: We performed a whole-genome loss-of-function screen to identify genes that mediate the effects of IFNalpha against human pathogenic viruses. We found that IFNalpha restricts HCV via actions of general and specific IEGs.
Title: RNA-Sequencing Quantification of Hepatic Ontogeny of Phase-I Enzymes in Mice Peng L, Cui JY, Yoo B, Gunewardena SS, Lu H, Klaassen CD, Zhong XB Ref: Drug Metabolism & Disposition: The Biological Fate of Chemicals, 41:2175, 2013 : PubMed
Phase-I drug metabolizing enzymes catalyze reactions of hydrolysis, reduction, and oxidation of drugs and play a critical role in drug metabolism. However, the functions of most phase-I enzymes are not mature at birth, which markedly affects drug metabolism in newborns. Therefore, characterization of the expression profiles of phase-I enzymes and the underlying regulatory mechanisms during liver maturation is needed for better estimation of using drugs in pediatric patients. The mouse is an animal model widely used for studying the mechanisms in the regulation of developmental expression of phase-I genes. Therefore, we applied RNA sequencing to provide a "true quantification" of the mRNA expression of phase-I genes in the mouse liver during development. Liver samples of male C57BL/6 mice at 12 different ages from prenatal to adulthood were used for defining the ontogenic mRNA profiles of phase-I families, including hydrolysis: carboxylesterase (Ces), paraoxonase (Pon), and epoxide hydrolase (Ephx); reduction: aldo-keto reductase (Akr), quinone oxidoreductase (Nqo), and dihydropyrimidine dehydrogenase (Dpyd); and oxidation: alcohol dehydrogenase (Adh), aldehyde dehydrogenase (Aldh), flavin monooxygenases (Fmo), molybdenum hydroxylase (Aox and Xdh), cytochrome P450 (P450), and cytochrome P450 oxidoreductase (Por). Two rapidly increasing stages of total phase-I gene expression after birth reflect functional transition of the liver during development. Diverse expression patterns were identified, and some large gene families contained the mRNA of genes that are enriched at different stages of development. Our study reveals the mRNA abundance of phase-I genes in the mouse liver during development and provides a valuable foundation for mechanistic studies in the future.
Cholinergic dysfunction is known as a hallmark feature of Alzheimer's disease (AD). Measurement of endogenous acetylcholine (ACh) in specific brain regions is important in understanding the pathology of AD and in designing and evaluating novel cholinomimetic agents for the treatment of AD. Since ACh is an endogenous neurotransmitter, there is no real blank matrix available to construct standard curves. It has been a challenging task to determine ACh in complex brain matrices. To overcome these difficulties, we employed a surrogate analyte strategy using ACh-d(4) instead of ACh to generate calibration curves and Ch-d(9) as internal standard (IS). The brain samples were deproteinized by acetonitrile with IS. Analytes and IS were separated by a HILIC column with the mobile phase composed of 20 mM ammonium formate in water-acetonitrile (30:70, v/v, adjusted to pH 3.0 with formic acid) and monitored in multiple reaction monitoring (MRM) mode using a positive electrospray source. The concentrations of endogenous ACh were calculated based on the peak area ratio of the analyte to the IS using a regression equation for the corresponding surrogate standard (ACh-d(4)). The lower limit of detection was 0.2 ng/mL and linearity was maintained over the range of 10-1000 ng/mL. Compared to other currently available methods, this approach offers improved accuracy and precision for efficient analysis of ACh. The proposed method was proved successfully by evaluating the action of typical acetylcholinesterase inhibitor huperzine A in senescence accelerated mouse prone 8 (SAMP8).
A novel alpha 7 nAChR agonist, 4-(5-methyloxazolo[4,5-b]pyridin-2-yl)-1,4-diazabicyclo[3.2.2]nonane (24, CP-810,123), has been identified as a potential treatment for cognitive deficits associated with psychiatric or neurological conditions including schizophrenia and Alzheimer's disease. Compound 24 is a potent and selective compound with excellent pharmaceutical properties. In rodent, the compound displays high oral bioavailability and excellent brain penetration affording high levels of receptor occupancy and in vivo efficacy in auditory sensory gating and novel object recognition. The structural diversity of this compound and its preclinical in vitro and in vivo package support the hypothesis that alpha 7 nAChR agonists may have potential as a pharmacotherapy for the treatment of cognitive deficits in schizophrenia.
Title: Diethyl 2,6-dimethyl-4-phenyl-1,4-dihydro-pyridine-3,5-dicarboxyl-ate Bai MS, Chen YY, Niu DL, Peng L Ref: Acta Crystallographica Sect E Struct Rep Online, 65:o799, 2009 : PubMed
The title mol-ecule, C(19)H(23)NO(4), was synthesized by the reaction of benzaldehyde, ethyl acetoacetate and NH(4)HCO(3). The dihydro-pyridine ring adopts a flattened boat conformation and the plane of the base of the boat forms a dihedral angle of 88.78 (9) degrees with the phenyl ring. The packing is stabilized by strong inter-molecular N-Hcdots, three dots, centeredO and weak inter-molecular C-Hcdots, three dots, centeredO hydrogen bonds.
Title: Evolution of X-degenerate Y chromosome genes in greater apes: conservation of gene content in human and gorilla, but not chimpanzee Goto H, Peng L, Makova KD Ref: Journal of Molecular Evolution, 68:134, 2009 : PubMed
Compared with the X chromosome, the mammalian Y chromosome is considerably diminished in size and has lost most of its ancestral genes during evolution. Interestingly, for the X-degenerate region on the Y chromosome, human has retained all 16 genes, while chimpanzee has lost 4 of the 16 genes since the divergence of the two species. To uncover the evolutionary forces governing ape Y chromosome degeneration, we determined the complete sequences of the coding exons and splice sites for 16 gorilla Y chromosome genes of the X-degenerate region. We discovered that all studied reading frames and splice sites were intact, and thus, this genomic region experienced no gene loss in the gorilla lineage. Higher nucleotide divergence was observed in the chimpanzee than the human lineage, particularly for genes with disruptive mutations, suggesting a lack of functional constraints for these genes in chimpanzee. Surprisingly, our results indicate that the human and gorilla orthologues of the genes disrupted in chimpanzee evolve under relaxed functional constraints and might not be essential. Taking mating patterns and effective population sizes of ape species into account, we conclude that genetic hitchhiking associated with positive selection due to sperm competition might explain the rapid decline in the Y chromosome gene number in chimpanzee. As we found no evidence of positive selection acting on the X-degenerate genes, such selection likely targets other genes on the chimpanzee Y chromosome.
The synthesis and SAR studies about the bicyclic amine, carbamate linker and aromatic ring of a 1,4-diazabicyclo[3.2.2]nonane phenyl carbamate series of alpha7 nAChR agonists is described. The development of the medicinal chemistry strategy and SAR which led to the identification of 5 and 7aa as subtype selective, high affinity alpha7 agonists as excellent leads for further evaluation is discussed, along with key physicochemical and pharmacokinetic data highlighting their lead potential.
New insecticides are urgently needed because resistance to current insecticides allows resurgence of disease-transmitting mosquitoes while concerns for human toxicity from current compounds are growing. We previously reported the finding of a free cysteine (Cys) residue at the entrance of the active site of acetylcholinesterase (AChE) in some insects but not in mammals, birds, and fish. These insects have two AChE genes (AP and AO), and only AP-AChE carries the Cys residue. Most of these insects are disease vectors such as the African malaria mosquito (Anopheles gambiae sensu stricto) or crop pests such as aphids. Recently we reported a Cys-targeting small molecule that irreversibly inhibited all AChE activity extracted from aphids while an identical exposure caused no effect on the human AChE. Full inhibition of AChE in aphids indicates that AP-AChE contributes most of the enzymatic activity and suggests that the Cys residue might serve as a target for developing better aphicides. It is therefore worth investigating whether the Cys-targeting strategy is applicable to mosquitocides. Herein, we report that, under conditions that spare the human AChE, a methanethiosulfonate-containing molecule at 6 microM irreversibly inhibited 95% of the AChE activity extracted from An. gambiae s. str. and >80% of the activity from the yellow fever mosquito (Aedes aegypti L.) or the northern house mosquito (Culex pipiens L.) that is a vector of St. Louis encephalitis. This type of inhibition is fast ( approximately 30 min) and due to conjugation of the inhibitor to the active-site Cys of mosquito AP-AChE, according to our observed reactivation of the methanethiosulfonate-inhibited AChE by 2-mercaptoethanol. We also note that our sulfhydryl agents partially and irreversibly inhibited the human AChE after prolonged exposure (>4 hr). This slow inhibition is due to partial enzyme denaturation by the inhibitor and/or micelles of the inhibitor, according to our studies using atomic force microscopy, circular dichroism spectroscopy, X-ray crystallography, time-resolved fluorescence spectroscopy, and liquid chromatography triple quadrupole mass spectrometry. These results support our view that the mosquito-specific Cys is a viable target for developing new mosquitocides to control disease vectors and to alleviate resistance problems with reduced toxicity toward non-target species.
By making use of the aggregation-induced emission feature of compound 1 and the cascade reactions among acetylthiocholine iodide (ATC), AChE, and compound 2, a new fluorescence "turn-on" method is developed for AChE assay and inhibitor-screening.
Title: Secretion, purification, and characterization of a recombinant Aspergillus oryzae tannase in Pichia pastoris Zhong X, Peng L, Zheng S, Sun Z, Ren Y, Dong M, Xu A Ref: Protein Expr Purif, 36:165, 2004 : PubMed
Tannase (tannin acyl hydrolase) is an industrially important enzyme produced by a large number of fungi, which hydrolyzes the ester and depside bonds of gallotannins and gallic acid esters. In the present work, a tannase from Aspergillus oryzae has been cloned and expressed in Pichia pastoris. The catalytic activity of the recombinant enzyme was assayed. A secretory form of enzyme was made with the aid of Saccharomyces cerevisiae alpha-factor, and a simple procedure purification protocol yielded tannase in pure form. The productivity of secreted tannase achieved 7000 IU/L by fed-batch culture. Recombinant tannase had a molecular mass of 90 kDa, which consisted of two kinds of subunits linked by a disulfide bond(s). Our study is the first report on the heterologous expression of tannase suggesting that the P. pastoris system represents an attractive means of generating large quantities of tannase for both research and industrial purpose.
Title: Mutually induced formation of host-guest complexes between p-sulfonated calix[8]arene and photolabile cholinergic ligands Specht A, Bernard P, Goeldner M, Peng L Ref: Angew Chem Int Ed Engl, 41:4706, 2002 : PubMed
A dynamic combinatorial library composed of interconverting acylhydrazones has been generated and screened towards inhibition of acetylcholinesterase from the electric ray Torpedo marmorata. Starting from a small set (13) of initial hydrazide and aldehyde building blocks, a library containing possibly 66 different species was obtained in a single operation. Of all possible acylhydrazones formed, active compounds containing two terminal cationic recognition groups separated by an appropriate distance, permitting two-site binding, could be rapidly identified by using a dynamic deconvolution--screening procedure, based on the sequential removal of starting building blocks. A very potent bis-pyridinium inhibitor (K(i)=1.09 nM, alphaK(i)=2.80 nM) was selected from the process and the contribution of various structural features to inhibitory potency was evaluated.
Title: Site-Directed Photo-Probes for Structural and Functional Investigations on Cholinesterases Nachon F, Colas C, Peng L, Ehret-Sabatier L, Goeldner M Ref: In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases, (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp.:379, 1998 : PubMed
Title: Caged Cholinergic Ligands and Photoregulation of Cholinesterase Activities Peng L, Goeldner M Ref: In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases, (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp.:253, 1998 : PubMed
As heavy-atom analogues of caged cholinergic ligands, the arsonium compounds 1-3 were synthesized for potential time-resolved crystallographic studies on cholinesterases. Compounds 1 and 3 possess the desired properties for dynamic studies on the catalytic mechanism of cholinesterases: structural similarity with the N-homologue, strong X-ray diffracting effect of arsenic, inhibitory effects on cholinesterases, and excellent photofragmentation kinetics.
Title: Photoregulation of cholinesterase activities with caged cholinergic ligands Peng L, Goeldner M Ref: Methods Enzymol, 291:265, 1998 : PubMed
Title: Biochemical evaluation of photolabile precursors of choline and of carbamylcholine for potential time-resolved crystallographic studies on cholinesterases Peng L, Silman I, Sussman JL, Goeldner M Ref: Biochemistry, 35:10854, 1996 : PubMed
Acetylcholinesterase and butyrylcholinesterase both rapidly hydrolyze the neurotransmitter acetylcholine. The unusual three-dimensional structure of acetylcholinesterase, in which the active site is located at the bottom of a deep and narrow gorge, raises cogent questions concerning traffic of the substrate, acetylcholine, and the products, choline and acetate, to and from the active site. Time-resolved crystallography offers a promising experimental approach to investigate this issue but requires a suitable triggering mechanism to ensure efficient and synchronized initiation of the dynamic process being monitored. Here we characterize the properties of two photolabile triggers which may serve as tools in time-resolved crystallographic studies of the cholinesterases. These compounds are 2-nitrobenzyl derivatives of choline and of carbamylcholine, which generate choline and carbamylcholine, respectively, upon photochemical fragmentation. Both photolabile compounds are reversible inhibitors, which bind at the active sites of acetylcholinesterase and butyrylcholinesterase with inhibition constants in the micromolar range, and both photofragmentation processes occur rapidly and with a high quantum yield, without substantial photochemical damage to the enzymes. Photolysis both of acetylcholinesterase and of butyrylcholinesterase, complexed with a 2-nitrobenzyl derivative of choline, resulted in regeneration of enzymic activity. Photolysis of acetylcholinesterase complexed with the 2-nitrobenzyl derivative of carbamylcholine led to time-dependent inactivation, resulting from carbamylation of acetylcholinesterase, which could be reversed upon dilution, due to decarbamylation. Both sets of experiments demonstrated release of choline within the active site. In the former case, choline was produced photochemically at the active site. In the latter case, choline was generated enzymatically, within the active site, concomitantly with carbamylation of the acetylcholinesterase. The two photolabile compounds may thus serve as complementary probes for time-resolved studies of the route of product release from the active sites of the cholinesterases.
Title: New Photolabile Inhibitors of Cholinesterases Designed for Rapid Photochemical Release of Choline Peng L, Goeldner M Ref: In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases, (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp.:219, 1995 : PubMed
