The soft rot infected by pathogenic bacterium Erwinia aroideae Holland is one of the three serious diseases of Chinese cabbage ( Brassica pekinensis Rupr.). By constructing vector system of high frequency transformati...The soft rot infected by pathogenic bacterium Erwinia aroideae Holland is one of the three serious diseases of Chinese cabbage ( Brassica pekinensis Rupr.). By constructing vector system of high frequency transformation mediated by Agrobacterium tunefaciens EHA105, anti-bacterial peptide gene with strong bactericidal action to pathogenic bacteria was introduced into Chinese cabbage AB-81 self-bred line and the transgenic plants were obtained. PCR and Southern blotting detection showed that target gene was integrated into plant genome of Chinese cabbage. The tests of bacteriostasis action of the extract from transgenic plants in vitro, and the assay of disease-resistant of transgenic plantlets in the tube and the pot by perfusing inoculation with pathogenic bacteria showed obvious resistance to soft rot. This resistance can be a stable heredity by genetic analysis of generations of transgenic plants self-bred, separation ratio of its R, was 3:1. The resistance to Km and disease of soft rot was still kept in the R-5. These results indicated the possibility of breeding new varieties of anti-soft rot Chinese cabbage by transgenic plants as parents.展开更多
The Rana temporaria chensinensis is an amphibian distributing mainly over the north of China. Its skin gland contains a variety of peptides, including antibacterial peptides. One of them, component 1, has been pur...The Rana temporaria chensinensis is an amphibian distributing mainly over the north of China. Its skin gland contains a variety of peptides, including antibacterial peptides. One of them, component 1, has been purified from the dried skin of R.temporaria chensinesis using a five step procedure. Purified component 1 has a molecular weight of 5 700 and its amino acid composition shows that it is devoid of disulfide bridges but rich in histine and glycine residues. Moreover, it has been found that it has a broad spectrum of antibacterial activity for Pseuctomonas aeruginosa, Escherichia coli, Bacillus sublilis, S. faccalis and Proteus vulgaris .展开更多
he Raman spectra of the antibacterial peptide βcomponent of silkworm· Bombyx Mori· pupae in aqueous solution have been studied. The results show that its mainchain consists of lots of αhelicals and only a ...he Raman spectra of the antibacterial peptide βcomponent of silkworm· Bombyx Mori· pupae in aqueous solution have been studied. The results show that its mainchain consists of lots of αhelicals and only a few βsheets and βturns. This suggests that the antibacterial peptide βcomponent may be the glycopeptide.展开更多
[ Objective ] This study aimed to extract antibacterial peptides from mussel. [ Method ] Blue mussels were used as raw materials for direct extraction of antibacterial peptides by using O. 5 % acetic acid, and the ant...[ Objective ] This study aimed to extract antibacterial peptides from mussel. [ Method ] Blue mussels were used as raw materials for direct extraction of antibacterial peptides by using O. 5 % acetic acid, and the antibacterial peptides were isolated and purified by Sephacryl S-100 polyacrylamide gel chromatography. The fractions were collected for measurement of antibacterial activity and minimum inhibitory concentration for a variety of bacterial species by filter paper diffusion assay. Molecular weight of the antibacterial peptides was determined by SDS-PAGE. Variation of antibacterial activity of antibacterial peptides was measured at 100 ~C under conditions of different processing time and different pH. [ Result] The O. 5% acetic acid was used for crude extraction of antibacterial peptides as extrac- tion solution and led to relatively high extraction efficiency. By using Sephacryl S-100, the antibacterial peptides could be purified as a single substance. The isola- ted and purified antibacterial peptides of mussel had relatively strong antibacterial properties with molecular weight of 5 908, showing heat-resistance acid-alkaline resistance. [ Conclusion] This study laid the theoretical foundation for large-scale production of antibacterial peotides.展开更多
[ Objective ] The paper was to isolate and preliminarily identify the antibacterial active substances of antagonistic actinomyeete strain G19 obtained from the soil highly affected by peach crown gall （Agrobacterium ...[ Objective ] The paper was to isolate and preliminarily identify the antibacterial active substances of antagonistic actinomyeete strain G19 obtained from the soil highly affected by peach crown gall （Agrobacterium tumefaciens）. [ Method] The antibacterial substances of antagonistic actinomycete strain G19 were ex- tracted using protein precipitation method, then isolated and purified using high performance liquid chromatography and medium-pressure preparative chromatogra- phy. Its molecular weight was determined by MALDI-TOFMS method, and the related functional groups were verified through chemical color reaction. [ Result] Seven peptide portions were produced from the antibacterial substances of antagonistic actinomycete strain G19 with the molecular weights of 900 - 1 300 Da after isolation and purification. It could be also inferred that it contained Cys, and carried with H2O and Na＋. Color reaction of functional groups verified that the sub- stance was polypeptide containing glycosyl. [ Conclusion] The result provided basis for the final definition of the structure of antibacterial substances in antagonistic actinomycete strain G19.展开更多
AIM:To investigate the antibacterial effects of a crude extract of maggots against Escherichia coli(E.coli) and the underlying mechanisms,and to separate and purifythe crude extract of maggots to assess the antibacter...AIM:To investigate the antibacterial effects of a crude extract of maggots against Escherichia coli(E.coli) and the underlying mechanisms,and to separate and purifythe crude extract of maggots to assess the antibacterial effects of the active ingredients in the crude extract.METHODS:Different concentrations of the crude extract of maggots were incubated with E.coli(O157:H7) and cultured.The optical density(OD) was measured at different time points to plot the OD-T curve.The effects of different concentrations of the crude extract on bacterial membrane permeability were determined by fluorescence probe technique.The effects of different concentrations of the crude extract on plasmid DNA replication were determined by agarose gel electrophoresis.DEAE-Sepharose ion exchange chromatography and Sephacryls-200 HR gel filtration chromatography were used to separate and purify the crude extract of maggots.The molecular weight of proteins in the purified crude extract was determined by SDS-PAGD electrophoresis,and its antibacterial effects were determined by turbidimetric method.RESULTS:The antibacterial effects of the crude extract of maggots at concentrations > 0.5 mg/m L were significant.The antibacterial effects of the crude extract at concentrations of 1.0,1.5 and 2.0 mg/m L did not differ significantly.Fluorescence probe analysis showed that the rate of membrane permeability change was 1223.1% in bacteria incubated with 2 mg/m L of the crude extract,and 1300.0% in those incubated with 80 mg/m L of the crude extract.Plasmid DNA was undetectable in E.coli incubated with 2 and 80 mg/m L of the crude extract.A low molecular weight protein band(about 15 k Da) was detected in the crude extract of maggots and eluent,but not in eluant,from DEAE-Sepharose ion exchange chromatography.The antibacterial effects of the crude extract of maggots and eluent were superior to those of eluant,with the antibacterial effects of eluents being better than those of the crude extract of maggots.Of 24 tubes offiltrates,the antibacterial effects of filtrates in tubes 4,5 and 11 were significantly higher than those of the control.The molecular weight of the protein in filtrates in tubes 4,5 and 11 was about 15 k Da.CONCLUSION:The crude extract of maggots exhibits obvious,dose-dependent antibacterial effects.The crude extract exerts antibacterial effects by changing the bacterial membrane permeability and inhibiting plasmid DNA replication.The prote in that has antibacterial effects in the crude extract of maggots has a molecular weight of about 15 k Da.展开更多
Peptides play crucial roles in various physiological and pathological processes. Consequently, the investigation of peptide-based drugs is a highlight in the research and development of new drugs. However, natural pep...Peptides play crucial roles in various physiological and pathological processes. Consequently, the investigation of peptide-based drugs is a highlight in the research and development of new drugs. However, natural peptides are not always ideal choices for clinical application due to their limited number and sometimes cytotoxicity to normal cells. Aiming to gain stronger or specific or novel biological effects and overcome the disadvantages of natural peptides, artificial hybrid peptides have been designed by combining the sequence of two or more different peptides with varied biological functions. Compared to natural peptides, hybrid peptides have shown better therapeutic potentials against bacteria, tumors, and metabolic diseases. In this review, design strategies, structure features and recent development of hybrid peptides are summarized;future directions for the research and development of hybrid peptide drugs are also discussed.展开更多
Endowing implant surfaces with combined antibacterial and osteogenic properties by drug-loaded coatings has made great strides,but how to achieve the combined excellence of infection-triggered bactericidal and in vivo...Endowing implant surfaces with combined antibacterial and osteogenic properties by drug-loaded coatings has made great strides,but how to achieve the combined excellence of infection-triggered bactericidal and in vivo-proven osteogenic activities without causing bacterial resistance still remains a formidable challenge.Herein,antimicrobial peptides(AMPs)with osteogenic fragments were designed and complexed on the surface of silver nanoparticle(AgNP)through hydrogen bonding,and the collagen structure-bionic silk fibroin(SF)was applied to carry AgNPs@AMPs to achieve infection-triggered antibacterial and osteointegration.As verified by TEM,AMPs contributed to the dispersion and size-regulation of AgNPs,with a particle size of about 20 nm,and a clear protein corona structure was observed on the particle surface.The release curve of silver ion displayed that the SF-based coating owned sensitive pH-responsive properties.In the antibacterial test against S.aureus for up to 21 days,the antibacterial rate had always remained above 99%.Meanwhile,the underlying mechanism was revealed,originating from the destruction of the bacterial cell membranes and ROS generation.The SF-based coating was conducive to the adhesion,diffusion,and proliferation of bone marrow stem cells(BMSCs)on the surface,and promoted the expression of osteogenic genes and collagen secretion.The in vivo implantation results showed that compared with the untreated Ti implants,SF-based coating enhanced osseointegration at week 4 and 8.Overall,the AgNPs@AMPs-loaded SF-based coating presented the ability to synergistically inhibit bacteria and promote osseointegration,possessing tremendous potential application prospects in bone defects and related-infection treatments.展开更多
AIM:To determine if and how a loop region in the peptide deformylase(PDF)of Chlamydia trachomatis regulates enzyme function. METHODS:Molecular dynamics simulation was used to study a structural model of the chlamydial...AIM:To determine if and how a loop region in the peptide deformylase(PDF)of Chlamydia trachomatis regulates enzyme function. METHODS:Molecular dynamics simulation was used to study a structural model of the chlamydial PDF(cPDF) and predict the temperature factor per residue for the protein backbone atoms.Site-directed mutagenesis was performed to construct cPDF variants.Catalytic properties of the resulting variants were determined by an enzyme assay using formyl-Met-Ala-Ser as a substrate. RESULTS:In silico analysis predicted a significant increase in atomic motion in the DGELV sequence(residues 68-72)of a loop region in a cPDF mutant,which isresistant to PDF inhibitors due to two amino acid substitutions near the active site,as compared to wild-type cPDF.The D68R and D68R/E70R cPDF variants demonstrated significantly increased catalytic efficiency.The E70R mutant showed only slightly decreased efficiency. Although deletion of residues 68-72 resulted in a nearly threefold loss in substrate binding,this deficiency was compensated for by increased catalytic efficiency. CONCLUSION:Movement of the DGELV loop region is involved in a rate-limiting conformational change of the enzyme during catalysis.However,there is no stringent sequence requirement for this region for cPDF enzyme activity.展开更多
Objective To identify a new peptide deformylase (PDF) gene (Genebank Accession AY238515) from Enterococcus faecium and to establish a new screening model targeted on PDF. Methods A new PDF gene was identified by BL...Objective To identify a new peptide deformylase (PDF) gene (Genebank Accession AY238515) from Enterococcus faecium and to establish a new screening model targeted on PDF. Methods A new PDF gene was identified by BLAST analysis and PCR and was subsequently over-expressed in the prokaryotic expression host E.coli Bl21(DE3). Over-expressed protein was purified for enzymatic assay by metal affinity chromatography and a new screening model was established for novel antibiotics. Result A new PDF gene of Enterococcus faecium was identified successfully. Ten positive samples were picked up from 8000 compound library and the microbial fermentation broth samples. Conclusion A new PDF of gene Enterococcus faecium was first identified and the model had a high efficacy. Positive samples screened may be antibacterial agents of broad spectrum.展开更多
With the advancement in cellular biology,the use of antimicrobial peptides(AMPs)against many drug-resistant pathogens has increased.AMPs have a broad range of activity and can work as antibacterial,antifungal,antivira...With the advancement in cellular biology,the use of antimicrobial peptides(AMPs)against many drug-resistant pathogens has increased.AMPs have a broad range of activity and can work as antibacterial,antifungal,antiviral,and sometimes even as anticancer peptides.The traditional methods of distinguishing AMPs from non-AMPs are based only on wet-lab experiments.Such experiments are both time-consuming and expensive.With the recent development in bioinformatics more and more researchers are contributing their effort to apply computational models to such problems.This study proposes a prediction algorithm for classifying AMPs and distinguishing between AMPs and non-AMPs.The proposed methodology uses machine learning algorithms to predict such sequences.A dataset was formulated based on 1902 samples of AMPs and 3997 samples of non-AMPs.Machine learning algorithms are trained on a xed number of succinct coefcients retaining sequence and composition information of primary structures.The features are extracted using position relative incidence and statistical moments.System performance is validated via various validation tests including a 10-fold cross-validation approach.An overall accuracy of 95.43%was achieved.A comparison of results with existing methodologies shows that the proposed methodology outperformed existing methodologies in terms of prediction accuracy.展开更多
Plant antimicrobial peptides are a very large family of antimicrobial peptides,which have strong resistance to various pathogenic microorganisms,especially fungi.With the increasing use of antibiotics,the problems cau...Plant antimicrobial peptides are a very large family of antimicrobial peptides,which have strong resistance to various pathogenic microorganisms,especially fungi.With the increasing use of antibiotics,the problems caused by antibiotics,including antibiotic residues and pathogen resistance,are becoming more and more prominent.The research on antimicrobial peptides as new antibiotic substitutes is also a hot spot.This article introduces the action sites and antibacterial mechanisms of several plant antimicrobial peptides,as well as the application of plant antimicrobial peptides in the fields of medicine,agriculture,and food preservation.展开更多
Antibacterial peptide is a small molecular weight,a substance existing in the biological body,plays a very important role in congenital immune systems.Today,in various antibiotics,the problem of drug resistance has ca...Antibacterial peptide is a small molecular weight,a substance existing in the biological body,plays a very important role in congenital immune systems.Today,in various antibiotics,the problem of drug resistance has caused people to live an indelible impact.Since the antibacterial peptide has spectral antibacterial properties,it has the characteristics of participating in human natural immunity and no residual,and is now one of the research and development hotspots.Antibacterial peptide is a recognized substance that can replace antibiotics,and people have never stopped,and new types of antimicrobial peptides have also emerged in the Volkswagen Vision.This paper is based on the use of antimicrosis peptides in daily life,briefly describes the effects of antimicrobial peptides in medical,animal husbandry and industrial.展开更多
Antimicrobial peptides(AMPs)have recently been exploited to fabricate anti-infective medical devices due to their biocompatibility and ability to combat multidrug-resistant bacteria.Modern medical devices should be th...Antimicrobial peptides(AMPs)have recently been exploited to fabricate anti-infective medical devices due to their biocompatibility and ability to combat multidrug-resistant bacteria.Modern medical devices should be thoroughly sterilised before use to avoid cross-infection and disease transmission,consequently it is essential to evaluate whether AMPs withstand the sterilisation process or not.In this study,the effect of radiation sterilisation on the structure and properties of AMPs was explored.Fourteen AMPs formed from different monomers with different topologies were synthesised by ring-opening polymerisation of N-carboxyanhydrides.The results of solubility testing showed that the star-shaped AMPs changed from water-soluble to water-insoluble after irradiation,while the solubility of linear AMPs remained unchanged.Matrix-assisted laser desorption/ionisation time of flight mass spectrometry showed that the molecular weight of the linear AMPs underwent minimal changes after irradiation.The results of minimum inhibitory concentration assay also illustrated that radiation sterilisation had little effect on the antibacterial properties of the linear AMPs.Therefore,radiation sterilisation may be a feasible method for the sterilisation of AMPs,which have promising commercial applications in medical devices.展开更多
文摘The soft rot infected by pathogenic bacterium Erwinia aroideae Holland is one of the three serious diseases of Chinese cabbage ( Brassica pekinensis Rupr.). By constructing vector system of high frequency transformation mediated by Agrobacterium tunefaciens EHA105, anti-bacterial peptide gene with strong bactericidal action to pathogenic bacteria was introduced into Chinese cabbage AB-81 self-bred line and the transgenic plants were obtained. PCR and Southern blotting detection showed that target gene was integrated into plant genome of Chinese cabbage. The tests of bacteriostasis action of the extract from transgenic plants in vitro, and the assay of disease-resistant of transgenic plantlets in the tube and the pot by perfusing inoculation with pathogenic bacteria showed obvious resistance to soft rot. This resistance can be a stable heredity by genetic analysis of generations of transgenic plants self-bred, separation ratio of its R, was 3:1. The resistance to Km and disease of soft rot was still kept in the R-5. These results indicated the possibility of breeding new varieties of anti-soft rot Chinese cabbage by transgenic plants as parents.
文摘The Rana temporaria chensinensis is an amphibian distributing mainly over the north of China. Its skin gland contains a variety of peptides, including antibacterial peptides. One of them, component 1, has been purified from the dried skin of R.temporaria chensinesis using a five step procedure. Purified component 1 has a molecular weight of 5 700 and its amino acid composition shows that it is devoid of disulfide bridges but rich in histine and glycine residues. Moreover, it has been found that it has a broad spectrum of antibacterial activity for Pseuctomonas aeruginosa, Escherichia coli, Bacillus sublilis, S. faccalis and Proteus vulgaris .
文摘he Raman spectra of the antibacterial peptide βcomponent of silkworm· Bombyx Mori· pupae in aqueous solution have been studied. The results show that its mainchain consists of lots of αhelicals and only a few βsheets and βturns. This suggests that the antibacterial peptide βcomponent may be the glycopeptide.
基金Supported by Natural Science Foundation of Shandong Province ( ZR2009BM0190A)
文摘[ Objective ] This study aimed to extract antibacterial peptides from mussel. [ Method ] Blue mussels were used as raw materials for direct extraction of antibacterial peptides by using O. 5 % acetic acid, and the antibacterial peptides were isolated and purified by Sephacryl S-100 polyacrylamide gel chromatography. The fractions were collected for measurement of antibacterial activity and minimum inhibitory concentration for a variety of bacterial species by filter paper diffusion assay. Molecular weight of the antibacterial peptides was determined by SDS-PAGE. Variation of antibacterial activity of antibacterial peptides was measured at 100 ~C under conditions of different processing time and different pH. [ Result] The O. 5% acetic acid was used for crude extraction of antibacterial peptides as extrac- tion solution and led to relatively high extraction efficiency. By using Sephacryl S-100, the antibacterial peptides could be purified as a single substance. The isola- ted and purified antibacterial peptides of mussel had relatively strong antibacterial properties with molecular weight of 5 908, showing heat-resistance acid-alkaline resistance. [ Conclusion] This study laid the theoretical foundation for large-scale production of antibacterial peotides.
基金Supported by Beijing Natural Science Foundation( 5112010)Beijing Municipal Education Commission Grant ( KM200910020001)~~
文摘[ Objective ] The paper was to isolate and preliminarily identify the antibacterial active substances of antagonistic actinomyeete strain G19 obtained from the soil highly affected by peach crown gall （Agrobacterium tumefaciens）. [ Method] The antibacterial substances of antagonistic actinomycete strain G19 were ex- tracted using protein precipitation method, then isolated and purified using high performance liquid chromatography and medium-pressure preparative chromatogra- phy. Its molecular weight was determined by MALDI-TOFMS method, and the related functional groups were verified through chemical color reaction. [ Result] Seven peptide portions were produced from the antibacterial substances of antagonistic actinomycete strain G19 with the molecular weights of 900 - 1 300 Da after isolation and purification. It could be also inferred that it contained Cys, and carried with H2O and Na＋. Color reaction of functional groups verified that the sub- stance was polypeptide containing glycosyl. [ Conclusion] The result provided basis for the final definition of the structure of antibacterial substances in antagonistic actinomycete strain G19.
基金Supported by National Natural Science Foundation of China,No.81270052
文摘AIM:To investigate the antibacterial effects of a crude extract of maggots against Escherichia coli(E.coli) and the underlying mechanisms,and to separate and purifythe crude extract of maggots to assess the antibacterial effects of the active ingredients in the crude extract.METHODS:Different concentrations of the crude extract of maggots were incubated with E.coli(O157:H7) and cultured.The optical density(OD) was measured at different time points to plot the OD-T curve.The effects of different concentrations of the crude extract on bacterial membrane permeability were determined by fluorescence probe technique.The effects of different concentrations of the crude extract on plasmid DNA replication were determined by agarose gel electrophoresis.DEAE-Sepharose ion exchange chromatography and Sephacryls-200 HR gel filtration chromatography were used to separate and purify the crude extract of maggots.The molecular weight of proteins in the purified crude extract was determined by SDS-PAGD electrophoresis,and its antibacterial effects were determined by turbidimetric method.RESULTS:The antibacterial effects of the crude extract of maggots at concentrations > 0.5 mg/m L were significant.The antibacterial effects of the crude extract at concentrations of 1.0,1.5 and 2.0 mg/m L did not differ significantly.Fluorescence probe analysis showed that the rate of membrane permeability change was 1223.1% in bacteria incubated with 2 mg/m L of the crude extract,and 1300.0% in those incubated with 80 mg/m L of the crude extract.Plasmid DNA was undetectable in E.coli incubated with 2 and 80 mg/m L of the crude extract.A low molecular weight protein band(about 15 k Da) was detected in the crude extract of maggots and eluent,but not in eluant,from DEAE-Sepharose ion exchange chromatography.The antibacterial effects of the crude extract of maggots and eluent were superior to those of eluant,with the antibacterial effects of eluents being better than those of the crude extract of maggots.Of 24 tubes offiltrates,the antibacterial effects of filtrates in tubes 4,5 and 11 were significantly higher than those of the control.The molecular weight of the protein in filtrates in tubes 4,5 and 11 was about 15 k Da.CONCLUSION:The crude extract of maggots exhibits obvious,dose-dependent antibacterial effects.The crude extract exerts antibacterial effects by changing the bacterial membrane permeability and inhibiting plasmid DNA replication.The prote in that has antibacterial effects in the crude extract of maggots has a molecular weight of about 15 k Da.
基金This work was supported by the National Natural Science Foundation of China (Nos. 31471208 and 31671195)the Academic Frontier Youth Team Project of HUST (2015).
文摘Peptides play crucial roles in various physiological and pathological processes. Consequently, the investigation of peptide-based drugs is a highlight in the research and development of new drugs. However, natural peptides are not always ideal choices for clinical application due to their limited number and sometimes cytotoxicity to normal cells. Aiming to gain stronger or specific or novel biological effects and overcome the disadvantages of natural peptides, artificial hybrid peptides have been designed by combining the sequence of two or more different peptides with varied biological functions. Compared to natural peptides, hybrid peptides have shown better therapeutic potentials against bacteria, tumors, and metabolic diseases. In this review, design strategies, structure features and recent development of hybrid peptides are summarized;future directions for the research and development of hybrid peptide drugs are also discussed.
基金supported by the National Natural Science Foundation of China(Grant numbers 32071327,32101087)Shaanxi Science and Technology Association(2022JQ-312).
文摘Endowing implant surfaces with combined antibacterial and osteogenic properties by drug-loaded coatings has made great strides,but how to achieve the combined excellence of infection-triggered bactericidal and in vivo-proven osteogenic activities without causing bacterial resistance still remains a formidable challenge.Herein,antimicrobial peptides(AMPs)with osteogenic fragments were designed and complexed on the surface of silver nanoparticle(AgNP)through hydrogen bonding,and the collagen structure-bionic silk fibroin(SF)was applied to carry AgNPs@AMPs to achieve infection-triggered antibacterial and osteointegration.As verified by TEM,AMPs contributed to the dispersion and size-regulation of AgNPs,with a particle size of about 20 nm,and a clear protein corona structure was observed on the particle surface.The release curve of silver ion displayed that the SF-based coating owned sensitive pH-responsive properties.In the antibacterial test against S.aureus for up to 21 days,the antibacterial rate had always remained above 99%.Meanwhile,the underlying mechanism was revealed,originating from the destruction of the bacterial cell membranes and ROS generation.The SF-based coating was conducive to the adhesion,diffusion,and proliferation of bone marrow stem cells(BMSCs)on the surface,and promoted the expression of osteogenic genes and collagen secretion.The in vivo implantation results showed that compared with the untreated Ti implants,SF-based coating enhanced osseointegration at week 4 and 8.Overall,the AgNPs@AMPs-loaded SF-based coating presented the ability to synergistically inhibit bacteria and promote osseointegration,possessing tremendous potential application prospects in bone defects and related-infection treatments.
基金Supported by A grant from the National Institutes of Health (AI071954)to Fan H
文摘AIM:To determine if and how a loop region in the peptide deformylase(PDF)of Chlamydia trachomatis regulates enzyme function. METHODS:Molecular dynamics simulation was used to study a structural model of the chlamydial PDF(cPDF) and predict the temperature factor per residue for the protein backbone atoms.Site-directed mutagenesis was performed to construct cPDF variants.Catalytic properties of the resulting variants were determined by an enzyme assay using formyl-Met-Ala-Ser as a substrate. RESULTS:In silico analysis predicted a significant increase in atomic motion in the DGELV sequence(residues 68-72)of a loop region in a cPDF mutant,which isresistant to PDF inhibitors due to two amino acid substitutions near the active site,as compared to wild-type cPDF.The D68R and D68R/E70R cPDF variants demonstrated significantly increased catalytic efficiency.The E70R mutant showed only slightly decreased efficiency. Although deletion of residues 68-72 resulted in a nearly threefold loss in substrate binding,this deficiency was compensated for by increased catalytic efficiency. CONCLUSION:Movement of the DGELV loop region is involved in a rate-limiting conformational change of the enzyme during catalysis.However,there is no stringent sequence requirement for this region for cPDF enzyme activity.
基金This work was supported by National Natural Science Foundation of China (grant 30270042) and Technology Platform of New Drugs Screen from Ministry of Science and Technology of China (2002AA22343D).
文摘Objective To identify a new peptide deformylase (PDF) gene (Genebank Accession AY238515) from Enterococcus faecium and to establish a new screening model targeted on PDF. Methods A new PDF gene was identified by BLAST analysis and PCR and was subsequently over-expressed in the prokaryotic expression host E.coli Bl21(DE3). Over-expressed protein was purified for enzymatic assay by metal affinity chromatography and a new screening model was established for novel antibiotics. Result A new PDF gene of Enterococcus faecium was identified successfully. Ten positive samples were picked up from 8000 compound library and the microbial fermentation broth samples. Conclusion A new PDF of gene Enterococcus faecium was first identified and the model had a high efficacy. Positive samples screened may be antibacterial agents of broad spectrum.
基金funded by the Deanship of Scientic Research(DSR),King Abdulaziz University(https://www.kau.edu.sa/),Jeddah,under Grant No.(DF-794-611-1441).The authors,therefore,gratefully acknowledge DSR technical and nancial support.
文摘With the advancement in cellular biology,the use of antimicrobial peptides(AMPs)against many drug-resistant pathogens has increased.AMPs have a broad range of activity and can work as antibacterial,antifungal,antiviral,and sometimes even as anticancer peptides.The traditional methods of distinguishing AMPs from non-AMPs are based only on wet-lab experiments.Such experiments are both time-consuming and expensive.With the recent development in bioinformatics more and more researchers are contributing their effort to apply computational models to such problems.This study proposes a prediction algorithm for classifying AMPs and distinguishing between AMPs and non-AMPs.The proposed methodology uses machine learning algorithms to predict such sequences.A dataset was formulated based on 1902 samples of AMPs and 3997 samples of non-AMPs.Machine learning algorithms are trained on a xed number of succinct coefcients retaining sequence and composition information of primary structures.The features are extracted using position relative incidence and statistical moments.System performance is validated via various validation tests including a 10-fold cross-validation approach.An overall accuracy of 95.43%was achieved.A comparison of results with existing methodologies shows that the proposed methodology outperformed existing methodologies in terms of prediction accuracy.
文摘Plant antimicrobial peptides are a very large family of antimicrobial peptides,which have strong resistance to various pathogenic microorganisms,especially fungi.With the increasing use of antibiotics,the problems caused by antibiotics,including antibiotic residues and pathogen resistance,are becoming more and more prominent.The research on antimicrobial peptides as new antibiotic substitutes is also a hot spot.This article introduces the action sites and antibacterial mechanisms of several plant antimicrobial peptides,as well as the application of plant antimicrobial peptides in the fields of medicine,agriculture,and food preservation.
基金support provided by the National Natural Science Foundation of China(No.31900861).
文摘Antibacterial peptide is a small molecular weight,a substance existing in the biological body,plays a very important role in congenital immune systems.Today,in various antibiotics,the problem of drug resistance has caused people to live an indelible impact.Since the antibacterial peptide has spectral antibacterial properties,it has the characteristics of participating in human natural immunity and no residual,and is now one of the research and development hotspots.Antibacterial peptide is a recognized substance that can replace antibiotics,and people have never stopped,and new types of antimicrobial peptides have also emerged in the Volkswagen Vision.This paper is based on the use of antimicrosis peptides in daily life,briefly describes the effects of antimicrobial peptides in medical,animal husbandry and industrial.
基金National Natural Science Foundation of China(No.51873213)High-Tech Research&Development Program of CAS-WEGO Group,and National Key Research and Development Program of China(No.2021YFC2101700).
文摘Antimicrobial peptides(AMPs)have recently been exploited to fabricate anti-infective medical devices due to their biocompatibility and ability to combat multidrug-resistant bacteria.Modern medical devices should be thoroughly sterilised before use to avoid cross-infection and disease transmission,consequently it is essential to evaluate whether AMPs withstand the sterilisation process or not.In this study,the effect of radiation sterilisation on the structure and properties of AMPs was explored.Fourteen AMPs formed from different monomers with different topologies were synthesised by ring-opening polymerisation of N-carboxyanhydrides.The results of solubility testing showed that the star-shaped AMPs changed from water-soluble to water-insoluble after irradiation,while the solubility of linear AMPs remained unchanged.Matrix-assisted laser desorption/ionisation time of flight mass spectrometry showed that the molecular weight of the linear AMPs underwent minimal changes after irradiation.The results of minimum inhibitory concentration assay also illustrated that radiation sterilisation had little effect on the antibacterial properties of the linear AMPs.Therefore,radiation sterilisation may be a feasible method for the sterilisation of AMPs,which have promising commercial applications in medical devices.
