Sennoside A(SA),a typical prodrug,exerts its laxative effect only after its transformation into rheinanthrone catalyzed by gut microbial hydrolases and reductases.Hydrolases have been identified,but reductases remain ...Sennoside A(SA),a typical prodrug,exerts its laxative effect only after its transformation into rheinanthrone catalyzed by gut microbial hydrolases and reductases.Hydrolases have been identified,but reductases remain unknown.By linking a photoreactive group to the SA scaffold,we synthesized a photoaffinity probe to covalently label SA reductases and identified SA reductases using activity-based protein profiling(ABPP).From lysates of an active strain,Bifidobacterium pseudocatenulatum(B.pseudocatenulatum),397 proteins were enriched and subsequently identified using mass spectrometry(MS).Among these proteins,chromate reductase/nicotinamide adenine dinucleotide(NADH)phosphate(NADPH)-dependent flavin mononucleotide(FMN)reductase/oxygen-insensitive NADPH nitroreductase(nfrA)was identified as a potent SA reductase through further bioinformatic analysis and The Universal Protein Resource(UniProt)database screening.We also determined that recombinant nfrA could reduce SA.Our study contributes to further illuminating mechanisms of SA transformation to rheinanthrone and simultaneously offers an effective method to identify gut bacterial reductases.展开更多
This letter critically comments on the article by Zheng et al investigating the role of aucubin in alleviating diabetic neuropathic pain(DNP).DNP arises from hyperglycaemia-induced nerve injury and microglial reprogra...This letter critically comments on the article by Zheng et al investigating the role of aucubin in alleviating diabetic neuropathic pain(DNP).DNP arises from hyperglycaemia-induced nerve injury and microglial reprogramming toward aerobic glycolysis.Aldose reductase(also known as AKR1B1)redirects excess glucose flux through the polyol pathway,thus increasing oxidative stress and inflammation.Zheng et al show that aucubin,a plant iridoid glycoside,reverses streptozotocin-induced mechanical and thermal hypersensitivity and anxiety-like behaviour in mice.Mechanistically,aucubin restores microglial morphology,reduces glycolytic flux,enhances oxidative phosphorylation and lowers tumour necrosis factor-α,interleukin(IL)-1βand IL-6 levels in spinal tissue and cultures of the BV-2 microglial cell line.Network pharmacology and molecular docking analyses identify AKR1B1 as a key target,confirmed by the fact that short hairpin RNA knockdown of AKR1B1 eliminates the effects of aucubin.Contrary to the other studies,this study uniquely implicates the polyol pathway in microglial immunometabolism.展开更多
BACKGROUND Treatment of diabetic neuropathy is often limited by side effects.Aucubin,an iridoid glycoside derived from natural plants,exhibits notable anti-inflammatory and antioxidant properties.AIM To investigate th...BACKGROUND Treatment of diabetic neuropathy is often limited by side effects.Aucubin,an iridoid glycoside derived from natural plants,exhibits notable anti-inflammatory and antioxidant properties.AIM To investigate the effects of aucubin on diabetic neuropathic pain(DNP)and glycolysis and inflammation in microglia.METHODS Streptozotocin(STZ)was used to establish a DNP animal model.Blood glucose levels and body weight of mice were measured following STZ administration.Paw withdrawal threshold was calculated for mechanical allodynia.Paw withdrawal latency was recorded for thermal hyperalgesia.The open field test and elevated plus maze was used to assess locomotor activity and anxiety-like behavior.Western blotting was utilized for analysis of protein expression.Immunofluorescence staining was measured for morphometric analysis of microglia.Glycolysis and ATP synthesis in BV-2 cell lines were detected by metabolic extracellular flux analysis.The SwissTargetPrediction and STRING databases were used for comprehensive screening to identify potential target proteins for aucubin.The molecular docking between the possible target proteins and aucubin was investigated using Auto Dock Tool.The BV-2 cell line was transfected with lentiviral AKR1B1-shRNA to further ascertain the function of AKR1B1 in the impact of aucubin on aerobic glycolysis and inflammation during high glucose stimulation.RESULTS Aucubin significantly improved pain and anxiety-like behavior in STZ-induced diabetic mice and restored microglial aerobic glycolysis and inflammation.Several public databases and molecular docking studies suggested that AKR1B1,MMP2 and MMP9 are involved in the effect of aucubin on DNP.Aucubin failed to restore aerobic glycolysis and inflammation in the context of AKR1B1 deficiency.CONCLUSION Aucubin has potential as a therapeutic agent for alleviating DNP by inhibiting expression of AKR1B1.展开更多
Chiral N-substituted amino amides and esters are ubiquitous scaffolds in pesticides and pharmaceutical chemicals,but their asymmetric synthesis remains challenging especially for those with multiple chiral centers.In ...Chiral N-substituted amino amides and esters are ubiquitous scaffolds in pesticides and pharmaceutical chemicals,but their asymmetric synthesis remains challenging especially for those with multiple chiral centers.In this study,IR104 from Streptomyces aureocirculatus was identified from 157 wild-type imine reductases for the synthesis of(S)-2-((R)-2-oxo-4-propylpyrrolidin-1-yl)butanamide(antiepileptic drug Brivaracetam)via dynamic kinetic resolution reductive amination from ethyl 3-formylhexanoate and(S)-2-aminobutylamide with high diastereoselectivity.To further improve the catalytic efficiency of IR104,its mutant D191E/L195I/E253S/M258A(M3)was identified by saturation mutagenesis and iterative combinatorial mutagenesis,which exhibited a 102-fold increase in the catalytic efficiency relative to that of wild-type enzyme and high diastereoselectivity(98:2 d.r.).Crystal structural analysis and molecular dynamics simulations provided some insights into the molecular basis for the improved activity of the mutant enzyme.The imine reductase identified in this study could accept chiral amino amides/esters as amino donors for the dynamic kinetic resolution reductive amination of racemicα-substituted aldehydo-esters,expanding the substrate scope of imine reductases in the dynamic kinetic resolution-reductive amination.Finally,IR104-M3 was successfully used for the preparation of Brivaracetam at gram scale.Using this mutant,various N-substituted amino amides/esters with two chiral centers were also synthesized with up to 99:1 d.r.and 96%yields and subsequently converted intoγ-andδ-lactams,providing an efficient protocol for the synthesis of these important compounds via enzymatic dynamic kinetic resolution-reductive amination from simple building blocks.展开更多
Imine reductases(IREDs)have been extensively used for the imine reduction and reductive amination to access various amines.However,poor activity and severe substrate/product inhibition limit their widespread applicati...Imine reductases(IREDs)have been extensively used for the imine reduction and reductive amination to access various amines.However,poor activity and severe substrate/product inhibition limit their widespread application in industry.Herein,an engineered IRED from Streptomyces viridochromogenes was developed through four rounds of directed evolution.The engineered SvIRED displayed a significant increase in specific activity to 136.8 U mg^(-1),the highest reported for an IRED to date.Molecular dynamics simulations elucidated the surge in specific activity during mutations.The best mutant can also catalyse the reductive coupling of aldehyde homologs and primary amines with up to 66.9 U mg^(-1).Additionally,we established an in-situ product adsorption system using resin,which significantly alleviated substrate/product inhibition and enhanced substrate loading to 100 g L^(-1).Under optimal conditions,a wide range of chiral 2-aryl-pyrrolidines were successfully produced at high substrate loadings(50-100 g L^(-1))with enantiomeric excess over 99%.The usefulness of this biocatalytic system was further demonstrated by preparation of pharmaceutically relevant chiral 2-aryl pyrrolidines,particularly the decagram-scale synthesis of the key chiral aticaprant intermediate with 90%isolated yield,>99%ee,and 438 g L^(-1) d^(-1) space-time yield.展开更多
N-substituted furfurylamines(FAs)are valuable precursors for producing pharmacologically active compounds and polymers.However,enzymatic synthesis of the type of chemicals is still in its infancy.Here we report an imi...N-substituted furfurylamines(FAs)are valuable precursors for producing pharmacologically active compounds and polymers.However,enzymatic synthesis of the type of chemicals is still in its infancy.Here we report an imine reductase from Streptomyces albidoflavus(SaIRED)for the reductive amination of biobased furans.A simple,fast and interference-resistant high-throughput screening(HTS)method was developed,based on the coloration reaction of carbonyl compounds with 2,4-dinitrophenylhydrazine.The reductive amination activity of IREDs can be directly indicated by a colorimetric assay.With the reductive amination of furfural with allylamine as the model reaction,SaIRED with the activity of 4.8 U mg^(-1) was subjected to three rounds of protein engineering and screening by this HTS method,affording a high-activity tri-variant I127V/D241A/A242T(named M3,20.2 U mg^(-1)).The variant M3 showed broad substrate scope,and enabled efficient reductive amination of biobased furans with a variety of amines including small aliphatic amines and sterically hindered amines,giving the target FAs in yields up to>99%.In addition,other variants were identified for preparative-scale synthesis of commercially interesting amines such as N-2-(methylsulfonyl)ethyl-FA by the screen method,with isolated yields up to 87%and turnover numbers up to 9700 for enzyme.Gram-scale synthesis of N-allyl-FA,a valuable building block and potential polymer monomer,was implemented at 0.25 mol L^(-1) substrate loading by a whole-cell catalyst incorporating variant M3,with 4.7 g L^(-1) h^(-1) space-time yield and 91%isolated yield.展开更多
Cinnamoyl-CoA reductase (CCR) is responsible for the first committed reaction in monolignol biosynthesis, which diverts phenylpropanoid-derived metabolites into the biosynthesis of lignin. To gain a better understandi...Cinnamoyl-CoA reductase (CCR) is responsible for the first committed reaction in monolignol biosynthesis, which diverts phenylpropanoid-derived metabolites into the biosynthesis of lignin. To gain a better understanding of the lion biosynthesis in wheat development, two cDNAs encoding CCR were identified from wheat (Triticum aestivum L. cv. H4564). DNA sequence analyses indicated that the two cDNAs represent two classes of CCR. RT-PCR and Northern blot hybridization demonstrated that one of them, W-cr6, was expressed actively in stem and leaf tissue, the other one, W-cr19, was expressed in root and stem tissue. The results suggested that there are at least two genes encoded for CCR existing in wheat genome.展开更多
[Objective] The aim was to clone the cDNA and DNA sequences of the CCR （Cinnamoyl-CoA reductase） gene which involves in lignin biosynthesis, from Pennisetum purpureum, and to make comprehensive analysis on these seq...[Objective] The aim was to clone the cDNA and DNA sequences of the CCR （Cinnamoyl-CoA reductase） gene which involves in lignin biosynthesis, from Pennisetum purpureum, and to make comprehensive analysis on these sequences. [Method] CCR sequences were cloned from P. purpureum by using conventional RT-PCR and RACE （Rapid Amplification of cDNA Ends） methods; and the bioinformatic analyses of the CCR were conducted by means of NCBI, ProtParam ProtScale, TMHMM, TargetP, SignalP, Pfam20.0, Prosite, Swiss-Model, ClustalW2, DNAman, DNAstar and MEGA5. [Result] The cloned PpCCR （P. purpureum CCR） cDNA sequence was 1 316 bp, including a 1 110 bp ORF and 206 bp 3’-UTR. The cloned DNA sequence from PpCCR was 6 133 bp in full-length, containing five exons and four introns. Bioinformatic analysis indicated that PpCCR encoded a polypeptide of 369 amino acids, the secondary structure of which was primarily composed of random coil and α-helix, belonging to NAD-dependent epimerase/dehydratase family, and its co-factor binding sites and substrate binding sites were highly conserved. [Conclusion] DNA and cDNA sequences of CCR gene were obtained from P. purpureum, which had the typical characteristics of other homologous genes. The obtained bioinformatic data provided theoretical references for the further analysis of CCR and better application of P. purpureum in the future.展开更多
A series of N5-substituted 8-deaza-5,6,7,8-tetrahydromethotrexate derivatives were synthesized and evaluated as inhibitors of dihydrofolate reductase（DHFR）.The results indicated that modification of the pteridine ri...A series of N5-substituted 8-deaza-5,6,7,8-tetrahydromethotrexate derivatives were synthesized and evaluated as inhibitors of dihydrofolate reductase（DHFR）.The results indicated that modification of the pteridine ring of methotrexate（MTX） rendered poor activity against human DHFR.展开更多
Nitrate reductase activity (NRA) in different plant organs and leaves in different positions of Camptotheca acuminata seedlings was determined by an In vivo assay, the diurnal variation rhythm of NRA in leaves of diff...Nitrate reductase activity (NRA) in different plant organs and leaves in different positions of Camptotheca acuminata seedlings was determined by an In vivo assay, the diurnal variation rhythm of NRA in leaves of different positions was observed,and the correlations between leaf NRA, leaf area and lamina mass per unit area (LMA) were also examined. The results showed that NRA in the leaf was significantly highest, compared with that in other organs such as roots, stems and leaves. In this experiment, the 10 leaves were selected from the apex to the base of the seedlings in order. The different NRA occurred obviously in leaves of different positions of C. acuminata seedlings from the apex to the base, and NRA was higher in the 4th-6th leaves.The diurnal change rhythm of leaf NRA showed a one peak curve, and maximum NRA value appeared at about midday (at 12:30 or so). No obvious correlations between NRA and leaf area or lamina mass per unit area were observed. This study offered scientific foundation for the further research on nitrogen metabolism of C. acuminata.展开更多
[Objective] The research aimed to study the circadian rhythm of nitrate re- ductase activity （NRA） in plant. [Method] The wheat plants at heading stage were used as the materials for the measurement of dynamic chang...[Objective] The research aimed to study the circadian rhythm of nitrate re- ductase activity （NRA） in plant. [Method] The wheat plants at heading stage were used as the materials for the measurement of dynamic changes of nitrate reductase activity （NRA） within 24 h under the conditions of constant high temperature. [Resulti The fluctuation of NRA in wheat changed greatly from 20：00 pm to 11：00 am. The enzyme activity remained constant, but at 14：00 the enzyme activity was the high- est, higher than all the other time points except the enzyme activity measured at11：00. The enzyme activity was the lowest of 17：00, which was lower than all the other time points except the enzyme activity measured at 2：00. [Conclusion] There were autonomous rhythm changes of NRA in wheat in a certain degree.展开更多
A series of 4-phenoxy quinoline-based mevalonolactone derivatives have been synthesized and evaluated as 3-hydroxy-3-methylglutaryl CoA reductase （HMG CoA reductase） inhibitors.One member of this series,（4R,6S）-6-...A series of 4-phenoxy quinoline-based mevalonolactone derivatives have been synthesized and evaluated as 3-hydroxy-3-methylglutaryl CoA reductase （HMG CoA reductase） inhibitors.One member of this series,（4R,6S）-6-{（E）-2-[6-fluoro-7-chloro-4-（4-fluorophenoxy-quinoline）-3-yl-]-ethenyl}-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one （3d）,showed more potent activity than rosuvastatin or pitavastatin to inhibit the rat HMG CoA reductase in vitro.This compound was selected for the extensive preclinical development as a potential hypocholesterolemic candidate.展开更多
Background:The regulatory mechanisms governing vasculogenic mimicry(VM)in oral squamous cell carcinoma(OSCC)remain largely undefined.This study aimed to identify critical factors and elucidate the epigenetic mechanism...Background:The regulatory mechanisms governing vasculogenic mimicry(VM)in oral squamous cell carcinoma(OSCC)remain largely undefined.This study aimed to identify critical factors and elucidate the epigenetic mechanisms underlying VM in OSCC.Methods:Bioinformatics analysis was performed utilizing single-cell RNA-seq,bulk RNA-seq,and histone H3 lysine 27 acetylation(H3K27ac)Chromatin Immunoprecipitation(ChIP)-seq data obtained from The Cancer Genome Atlas(TCGA)and Gene Expression Omnibus(GEO)databases.ChIP-qPCR was used to validate the binding of ETS transcription factor ELK4(ELK4)to the dihydrofolate reductase(DHFR)enhancer.In vitro VM formation and invasion of OSCC cells were assessed using Matrigel-based tube formation and Transwell assays,respectively.Results:Elevated expression of VM-related genes predicts unfavorable prognosis in OSCC patients.High-dimensional weighted gene co-expression network analysis(hdWGCNA)identified epithelial subcluster C4 as most strongly associated with VM and metastasis.Three co-expression modules within this subcluster exhibited significant positive correlations with both phenotypic traits.Among the 30 eigengenes from the three modules,DHFR emerged as a key regulator of VM and metastasis.Knockdown or inhibition of DHFR significantly suppressed VM formation and invasion in OSCC cells.Mechanistically,ELK4 activated DHFR transcription through direct binding to its enhancer.DHFR overexpression rescued VM and invasion impairment induced by ELK4 knockdown.Conclusion:DHFR was a pivotal enhancer-regulated gene driving VM and metastasis in OSCC.ELK4 directly binds to DHFR enhancer regions to activate its transcription,thereby promoting these malignant phenotypes.These findings identified the ELK4/DHFR axis as a promising therapeutic target for anti-angiogenic intervention in OSCC.展开更多
Background Methane(CH_(4))emissions from ruminants significantly contribute to greenhouse gas effects and energy loss in livestock production.Methyl-coenzyme M reductase(MCR)is the key enzyme in methanogenesis,making ...Background Methane(CH_(4))emissions from ruminants significantly contribute to greenhouse gas effects and energy loss in livestock production.Methyl-coenzyme M reductase(MCR)is the key enzyme in methanogenesis,making it a promising target for CH_(4) mitigation.This study aimed to identify and validate plant-derived inhibitors by using molecular docking to screen compounds with strong binding affinity to the F430 active site of MCR and assessing their efficacy in reducing CH_(4) emissions.Results Molecular docking analysis identified salvianolic acid C(SAC)as a potent inhibitor of MCR,showing a strong binding affinity to the F430 active site(binding energy:-8.2 kcal/mol).Enzymatic inhibition assays confirmed its inhibitory effect,with a half-maximal inhibitory concentration(IC50)of 692.3μmol/L.In vitro rumen fermentation experiments demonstrated that SAC supplementation(1.5 mg/g DM)significantly reduced CH_(4)production(P<0.01)without negatively affecting major fermentation parameters.Microbial community analysis using 16S rRNA sequencing and metagenomics revealed that SAC selectively altered the rumen microbiota,increasing the relative abundance of Bacteroidota while significantly reducing Methanobrevibacter(P=0.04).Moreover,metagenomic analysis showed the downregulation of key methanogenesis-related genes(mcrA and rnfC),suggesting a dual mechanism involving direct enzymatic inhibition and microbial community modulation.Conclusions These findings indicate that SAC effectively reduces CH_(4)production by inhibiting MCR activity and reshaping the rumen microbial community.As a plant-derived compound with strong inhibitory effects on methanogenesis,SAC presents a promising and sustainable alternative to synthetic CH_(4) inhibitors,offering potential applications for mitigating CH_(4)emissions in livestock production.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.:U21A20407 and 81973467)Beijing Natural Science Foundation,China(Grant No.:7222276).
文摘Sennoside A(SA),a typical prodrug,exerts its laxative effect only after its transformation into rheinanthrone catalyzed by gut microbial hydrolases and reductases.Hydrolases have been identified,but reductases remain unknown.By linking a photoreactive group to the SA scaffold,we synthesized a photoaffinity probe to covalently label SA reductases and identified SA reductases using activity-based protein profiling(ABPP).From lysates of an active strain,Bifidobacterium pseudocatenulatum(B.pseudocatenulatum),397 proteins were enriched and subsequently identified using mass spectrometry(MS).Among these proteins,chromate reductase/nicotinamide adenine dinucleotide(NADH)phosphate(NADPH)-dependent flavin mononucleotide(FMN)reductase/oxygen-insensitive NADPH nitroreductase(nfrA)was identified as a potent SA reductase through further bioinformatic analysis and The Universal Protein Resource(UniProt)database screening.We also determined that recombinant nfrA could reduce SA.Our study contributes to further illuminating mechanisms of SA transformation to rheinanthrone and simultaneously offers an effective method to identify gut bacterial reductases.
基金Supported by the Top-level Talents Support Program of Yangzhou University“Lv Yang Jin Feng”Outstanding Doctor of Yangzhou,No.YZLYJFJH2023YXBS169Natural Science Foundation of Jiangsu Province,No.BK20240907.
文摘This letter critically comments on the article by Zheng et al investigating the role of aucubin in alleviating diabetic neuropathic pain(DNP).DNP arises from hyperglycaemia-induced nerve injury and microglial reprogramming toward aerobic glycolysis.Aldose reductase(also known as AKR1B1)redirects excess glucose flux through the polyol pathway,thus increasing oxidative stress and inflammation.Zheng et al show that aucubin,a plant iridoid glycoside,reverses streptozotocin-induced mechanical and thermal hypersensitivity and anxiety-like behaviour in mice.Mechanistically,aucubin restores microglial morphology,reduces glycolytic flux,enhances oxidative phosphorylation and lowers tumour necrosis factor-α,interleukin(IL)-1βand IL-6 levels in spinal tissue and cultures of the BV-2 microglial cell line.Network pharmacology and molecular docking analyses identify AKR1B1 as a key target,confirmed by the fact that short hairpin RNA knockdown of AKR1B1 eliminates the effects of aucubin.Contrary to the other studies,this study uniquely implicates the polyol pathway in microglial immunometabolism.
基金Supported by National Natural Science Foundation of China,No.82001424.
文摘BACKGROUND Treatment of diabetic neuropathy is often limited by side effects.Aucubin,an iridoid glycoside derived from natural plants,exhibits notable anti-inflammatory and antioxidant properties.AIM To investigate the effects of aucubin on diabetic neuropathic pain(DNP)and glycolysis and inflammation in microglia.METHODS Streptozotocin(STZ)was used to establish a DNP animal model.Blood glucose levels and body weight of mice were measured following STZ administration.Paw withdrawal threshold was calculated for mechanical allodynia.Paw withdrawal latency was recorded for thermal hyperalgesia.The open field test and elevated plus maze was used to assess locomotor activity and anxiety-like behavior.Western blotting was utilized for analysis of protein expression.Immunofluorescence staining was measured for morphometric analysis of microglia.Glycolysis and ATP synthesis in BV-2 cell lines were detected by metabolic extracellular flux analysis.The SwissTargetPrediction and STRING databases were used for comprehensive screening to identify potential target proteins for aucubin.The molecular docking between the possible target proteins and aucubin was investigated using Auto Dock Tool.The BV-2 cell line was transfected with lentiviral AKR1B1-shRNA to further ascertain the function of AKR1B1 in the impact of aucubin on aerobic glycolysis and inflammation during high glucose stimulation.RESULTS Aucubin significantly improved pain and anxiety-like behavior in STZ-induced diabetic mice and restored microglial aerobic glycolysis and inflammation.Several public databases and molecular docking studies suggested that AKR1B1,MMP2 and MMP9 are involved in the effect of aucubin on DNP.Aucubin failed to restore aerobic glycolysis and inflammation in the context of AKR1B1 deficiency.CONCLUSION Aucubin has potential as a therapeutic agent for alleviating DNP by inhibiting expression of AKR1B1.
文摘Chiral N-substituted amino amides and esters are ubiquitous scaffolds in pesticides and pharmaceutical chemicals,but their asymmetric synthesis remains challenging especially for those with multiple chiral centers.In this study,IR104 from Streptomyces aureocirculatus was identified from 157 wild-type imine reductases for the synthesis of(S)-2-((R)-2-oxo-4-propylpyrrolidin-1-yl)butanamide(antiepileptic drug Brivaracetam)via dynamic kinetic resolution reductive amination from ethyl 3-formylhexanoate and(S)-2-aminobutylamide with high diastereoselectivity.To further improve the catalytic efficiency of IR104,its mutant D191E/L195I/E253S/M258A(M3)was identified by saturation mutagenesis and iterative combinatorial mutagenesis,which exhibited a 102-fold increase in the catalytic efficiency relative to that of wild-type enzyme and high diastereoselectivity(98:2 d.r.).Crystal structural analysis and molecular dynamics simulations provided some insights into the molecular basis for the improved activity of the mutant enzyme.The imine reductase identified in this study could accept chiral amino amides/esters as amino donors for the dynamic kinetic resolution reductive amination of racemicα-substituted aldehydo-esters,expanding the substrate scope of imine reductases in the dynamic kinetic resolution-reductive amination.Finally,IR104-M3 was successfully used for the preparation of Brivaracetam at gram scale.Using this mutant,various N-substituted amino amides/esters with two chiral centers were also synthesized with up to 99:1 d.r.and 96%yields and subsequently converted intoγ-andδ-lactams,providing an efficient protocol for the synthesis of these important compounds via enzymatic dynamic kinetic resolution-reductive amination from simple building blocks.
文摘Imine reductases(IREDs)have been extensively used for the imine reduction and reductive amination to access various amines.However,poor activity and severe substrate/product inhibition limit their widespread application in industry.Herein,an engineered IRED from Streptomyces viridochromogenes was developed through four rounds of directed evolution.The engineered SvIRED displayed a significant increase in specific activity to 136.8 U mg^(-1),the highest reported for an IRED to date.Molecular dynamics simulations elucidated the surge in specific activity during mutations.The best mutant can also catalyse the reductive coupling of aldehyde homologs and primary amines with up to 66.9 U mg^(-1).Additionally,we established an in-situ product adsorption system using resin,which significantly alleviated substrate/product inhibition and enhanced substrate loading to 100 g L^(-1).Under optimal conditions,a wide range of chiral 2-aryl-pyrrolidines were successfully produced at high substrate loadings(50-100 g L^(-1))with enantiomeric excess over 99%.The usefulness of this biocatalytic system was further demonstrated by preparation of pharmaceutically relevant chiral 2-aryl pyrrolidines,particularly the decagram-scale synthesis of the key chiral aticaprant intermediate with 90%isolated yield,>99%ee,and 438 g L^(-1) d^(-1) space-time yield.
文摘N-substituted furfurylamines(FAs)are valuable precursors for producing pharmacologically active compounds and polymers.However,enzymatic synthesis of the type of chemicals is still in its infancy.Here we report an imine reductase from Streptomyces albidoflavus(SaIRED)for the reductive amination of biobased furans.A simple,fast and interference-resistant high-throughput screening(HTS)method was developed,based on the coloration reaction of carbonyl compounds with 2,4-dinitrophenylhydrazine.The reductive amination activity of IREDs can be directly indicated by a colorimetric assay.With the reductive amination of furfural with allylamine as the model reaction,SaIRED with the activity of 4.8 U mg^(-1) was subjected to three rounds of protein engineering and screening by this HTS method,affording a high-activity tri-variant I127V/D241A/A242T(named M3,20.2 U mg^(-1)).The variant M3 showed broad substrate scope,and enabled efficient reductive amination of biobased furans with a variety of amines including small aliphatic amines and sterically hindered amines,giving the target FAs in yields up to>99%.In addition,other variants were identified for preparative-scale synthesis of commercially interesting amines such as N-2-(methylsulfonyl)ethyl-FA by the screen method,with isolated yields up to 87%and turnover numbers up to 9700 for enzyme.Gram-scale synthesis of N-allyl-FA,a valuable building block and potential polymer monomer,was implemented at 0.25 mol L^(-1) substrate loading by a whole-cell catalyst incorporating variant M3,with 4.7 g L^(-1) h^(-1) space-time yield and 91%isolated yield.
文摘Cinnamoyl-CoA reductase (CCR) is responsible for the first committed reaction in monolignol biosynthesis, which diverts phenylpropanoid-derived metabolites into the biosynthesis of lignin. To gain a better understanding of the lion biosynthesis in wheat development, two cDNAs encoding CCR were identified from wheat (Triticum aestivum L. cv. H4564). DNA sequence analyses indicated that the two cDNAs represent two classes of CCR. RT-PCR and Northern blot hybridization demonstrated that one of them, W-cr6, was expressed actively in stem and leaf tissue, the other one, W-cr19, was expressed in root and stem tissue. The results suggested that there are at least two genes encoded for CCR existing in wheat genome.
基金Supported by the National Natural Science Foundation of China(30972138)the Guangdong Natural Science Foundation(9451064201003804)~~
文摘[Objective] The aim was to clone the cDNA and DNA sequences of the CCR （Cinnamoyl-CoA reductase） gene which involves in lignin biosynthesis, from Pennisetum purpureum, and to make comprehensive analysis on these sequences. [Method] CCR sequences were cloned from P. purpureum by using conventional RT-PCR and RACE （Rapid Amplification of cDNA Ends） methods; and the bioinformatic analyses of the CCR were conducted by means of NCBI, ProtParam ProtScale, TMHMM, TargetP, SignalP, Pfam20.0, Prosite, Swiss-Model, ClustalW2, DNAman, DNAstar and MEGA5. [Result] The cloned PpCCR （P. purpureum CCR） cDNA sequence was 1 316 bp, including a 1 110 bp ORF and 206 bp 3’-UTR. The cloned DNA sequence from PpCCR was 6 133 bp in full-length, containing five exons and four introns. Bioinformatic analysis indicated that PpCCR encoded a polypeptide of 369 amino acids, the secondary structure of which was primarily composed of random coil and α-helix, belonging to NAD-dependent epimerase/dehydratase family, and its co-factor binding sites and substrate binding sites were highly conserved. [Conclusion] DNA and cDNA sequences of CCR gene were obtained from P. purpureum, which had the typical characteristics of other homologous genes. The obtained bioinformatic data provided theoretical references for the further analysis of CCR and better application of P. purpureum in the future.
基金National Natural Science Foundation of China(Grant No.20972011)
文摘A series of N5-substituted 8-deaza-5,6,7,8-tetrahydromethotrexate derivatives were synthesized and evaluated as inhibitors of dihydrofolate reductase（DHFR）.The results indicated that modification of the pteridine ring of methotrexate（MTX） rendered poor activity against human DHFR.
文摘Nitrate reductase activity (NRA) in different plant organs and leaves in different positions of Camptotheca acuminata seedlings was determined by an In vivo assay, the diurnal variation rhythm of NRA in leaves of different positions was observed,and the correlations between leaf NRA, leaf area and lamina mass per unit area (LMA) were also examined. The results showed that NRA in the leaf was significantly highest, compared with that in other organs such as roots, stems and leaves. In this experiment, the 10 leaves were selected from the apex to the base of the seedlings in order. The different NRA occurred obviously in leaves of different positions of C. acuminata seedlings from the apex to the base, and NRA was higher in the 4th-6th leaves.The diurnal change rhythm of leaf NRA showed a one peak curve, and maximum NRA value appeared at about midday (at 12:30 or so). No obvious correlations between NRA and leaf area or lamina mass per unit area were observed. This study offered scientific foundation for the further research on nitrogen metabolism of C. acuminata.
基金Supported by the National Natural Science Foundation of China(31160254)~~
文摘[Objective] The research aimed to study the circadian rhythm of nitrate re- ductase activity （NRA） in plant. [Method] The wheat plants at heading stage were used as the materials for the measurement of dynamic changes of nitrate reductase activity （NRA） within 24 h under the conditions of constant high temperature. [Resulti The fluctuation of NRA in wheat changed greatly from 20：00 pm to 11：00 am. The enzyme activity remained constant, but at 14：00 the enzyme activity was the high- est, higher than all the other time points except the enzyme activity measured at11：00. The enzyme activity was the lowest of 17：00, which was lower than all the other time points except the enzyme activity measured at 2：00. [Conclusion] There were autonomous rhythm changes of NRA in wheat in a certain degree.
基金The State New Drug Innovation (Grant No. 2009ZX09301-007)Shanghai Rising-Star Program (Grant No. 08QB1403800)Shanghai Innovation Action Project (Grant No. 09431901300)
文摘A series of 4-phenoxy quinoline-based mevalonolactone derivatives have been synthesized and evaluated as 3-hydroxy-3-methylglutaryl CoA reductase （HMG CoA reductase） inhibitors.One member of this series,（4R,6S）-6-{（E）-2-[6-fluoro-7-chloro-4-（4-fluorophenoxy-quinoline）-3-yl-]-ethenyl}-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one （3d）,showed more potent activity than rosuvastatin or pitavastatin to inhibit the rat HMG CoA reductase in vitro.This compound was selected for the extensive preclinical development as a potential hypocholesterolemic candidate.
基金supported by Hebei Natural Science Foundation(H2024206476)Medical Science Research Project of Hebei(20240101).
文摘Background:The regulatory mechanisms governing vasculogenic mimicry(VM)in oral squamous cell carcinoma(OSCC)remain largely undefined.This study aimed to identify critical factors and elucidate the epigenetic mechanisms underlying VM in OSCC.Methods:Bioinformatics analysis was performed utilizing single-cell RNA-seq,bulk RNA-seq,and histone H3 lysine 27 acetylation(H3K27ac)Chromatin Immunoprecipitation(ChIP)-seq data obtained from The Cancer Genome Atlas(TCGA)and Gene Expression Omnibus(GEO)databases.ChIP-qPCR was used to validate the binding of ETS transcription factor ELK4(ELK4)to the dihydrofolate reductase(DHFR)enhancer.In vitro VM formation and invasion of OSCC cells were assessed using Matrigel-based tube formation and Transwell assays,respectively.Results:Elevated expression of VM-related genes predicts unfavorable prognosis in OSCC patients.High-dimensional weighted gene co-expression network analysis(hdWGCNA)identified epithelial subcluster C4 as most strongly associated with VM and metastasis.Three co-expression modules within this subcluster exhibited significant positive correlations with both phenotypic traits.Among the 30 eigengenes from the three modules,DHFR emerged as a key regulator of VM and metastasis.Knockdown or inhibition of DHFR significantly suppressed VM formation and invasion in OSCC cells.Mechanistically,ELK4 activated DHFR transcription through direct binding to its enhancer.DHFR overexpression rescued VM and invasion impairment induced by ELK4 knockdown.Conclusion:DHFR was a pivotal enhancer-regulated gene driving VM and metastasis in OSCC.ELK4 directly binds to DHFR enhancer regions to activate its transcription,thereby promoting these malignant phenotypes.These findings identified the ELK4/DHFR axis as a promising therapeutic target for anti-angiogenic intervention in OSCC.
基金funded by the Integrated Demonstration of Scalable and Efficient Healthy Breeding for Cattle and Sheep(Grant No.2022YFD1301100)Instant Intelligent Diagnosis and Risk Warning Methods for Nutritional and Metabolic-Type Periparturient Cow Paralysis(Grant No.2024-YWF-ZYSQ-10)。
文摘Background Methane(CH_(4))emissions from ruminants significantly contribute to greenhouse gas effects and energy loss in livestock production.Methyl-coenzyme M reductase(MCR)is the key enzyme in methanogenesis,making it a promising target for CH_(4) mitigation.This study aimed to identify and validate plant-derived inhibitors by using molecular docking to screen compounds with strong binding affinity to the F430 active site of MCR and assessing their efficacy in reducing CH_(4) emissions.Results Molecular docking analysis identified salvianolic acid C(SAC)as a potent inhibitor of MCR,showing a strong binding affinity to the F430 active site(binding energy:-8.2 kcal/mol).Enzymatic inhibition assays confirmed its inhibitory effect,with a half-maximal inhibitory concentration(IC50)of 692.3μmol/L.In vitro rumen fermentation experiments demonstrated that SAC supplementation(1.5 mg/g DM)significantly reduced CH_(4)production(P<0.01)without negatively affecting major fermentation parameters.Microbial community analysis using 16S rRNA sequencing and metagenomics revealed that SAC selectively altered the rumen microbiota,increasing the relative abundance of Bacteroidota while significantly reducing Methanobrevibacter(P=0.04).Moreover,metagenomic analysis showed the downregulation of key methanogenesis-related genes(mcrA and rnfC),suggesting a dual mechanism involving direct enzymatic inhibition and microbial community modulation.Conclusions These findings indicate that SAC effectively reduces CH_(4)production by inhibiting MCR activity and reshaping the rumen microbial community.As a plant-derived compound with strong inhibitory effects on methanogenesis,SAC presents a promising and sustainable alternative to synthetic CH_(4) inhibitors,offering potential applications for mitigating CH_(4)emissions in livestock production.
