| Antibacterial peptide(Antimicrobial peptides,AMPs)as a kind of cationic small molecular peptide is one of the important components,organisms innate immune system as a broad-spectrum of antimicrobial activity and the lower possibility to produce resistant of strains,these features attracted a lot of attention in this field.CecMd is a kind of cecropin like antibacterial peptide found in housefly with broad-spectrum antibacterial activity,but also there is similar cytotoxicity to the Cecropin B,so knowing the information in the chain,optimizing amino acids composition,even carrying to molecular hybridization would be speedy pathways.This objective in this study was to know information of the CecMd and antibacterial activity,we had constructed a library of peptides by cutting amino acid of C and N terminal successively.5 CecMd analogs were selected accord to the distribution of amino acids in peptides align in library,and 11 hybrid peptides were constructed by fragments of peptides from the CecMd library and frog skin peptides and Magainin.The main research results showed:(1)341 sequences of antibacterial peptides could be checked by a series of analysis using biological software or bio-informational system online after cutting,while 263 peptides have antibacterial activity potentially,230 peptides could formed the spiral wheel and hydrophobic surface.We screened 5 CecMd analogs CM18、CM29、CM34、CC34s、CM33 from library,11 hybrid peptides had been constructed as CR33、C8RN11、C9RN12、C9RN10、C12RN11 from functional sequences of CecMd and Dybowskin-1CDYa,C8M7、C8M10、C9M10、C10M10 and C15M10 from CecMd and Magainina,furthermore,they were identified to have antimicrobial resistance by a series of bio-informational system analysis,and synthesis had been done for all.(2)The bacteriostatic circle of new synthetic 16 hybrid peptides showed that there are diverse resistance for 16 antibacterial peptides to E coli,S.aureus,S.dysgalactiae and S.paratyphus,It present a strong antibacterial properties for CM18,CC34 s,CR33,C9RN10,C9M10 and C15M10 to E.coli,an obvious antibacterial activity for CM18,CM29,CM34,CM30,CR33,C8RN11 and C9RN12 to staphylococcus aureus successively.MIC showed that the 16 peptides for all have good antibacterial activities,MIC ranged 16～32μg/ml to E.coli,S.aureus and S.dysgalactiae,then to S.paratyphus is 8～16μg/ml.Hemolysis of the 16 peptides showed lower hemolysis compared to CecMd.The thermal stability of the antimicrobial peptide showed that the thermal resistance of the hybrid peptides was ideal for all.(3)The CD spectrum of antibacterial peptide showed that the secondary structure of 16 hybrid peptides present random curl in the water environment.Except C8RN11,the others peptides showed a positive band in the vicinity of 192 nm,and present two shoulder peak between 208 to 222 nm in the environment of phosphate buffer and the simulative prokaryotes with negative charge(30 m M SDS solution),there is a typical alpha helix structure characteristics in the negative area.Conclusion: 16 novel antibacterial peptides with different biological activities had been designed in this study successfully,the relationship between the structural function of antibacterial peptides,preliminary had been discussed,and they can be used as a substitute for antibiotics in the future,they also can be used to expand the antimicrobial peptide library,and provide a certain theoretical data at the same time. |
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