Penicillin discovery makes people's various diseases caused by pathogenic microorganisms, and thereby develop a large amount of beta-lactam antibiotics, which make great contribution to protect human health. However, as the above "traditional antibiotics" is widely used, many new problems have been continuously produced. As the allergic reaction of β-lactam antibiotics, the production of anti-drug strains is used for long-term use. So people start looking for a new generation of antibacterial agents. Recent studies have found that certain cationic polypeptides have a broad spectrum of antibacterial activity, while having a "traditional antibiotic" unacceptable superiority: no induction of anti-drug strains, and hope to become a new generation of antibacterial agents [1]. AntiMicrobial Peptides is a general term having antibacterial active short peptides. In 1975, Swedish scientists G.Boman et al. [2] were induced from Hyatophoracecropia, and they were named Cecropin. Thereafter, many antimicrobial peptides are successively separated and purified. Some antimicrobial peptides of the amino acid primary structure and gene sequence are determined. In the 1980s, research on antimicrosis was mainly concentrated in large economic insects. In the 1990s, while continuing to study large economic insects, it has been extended to some small insects and other invertebrates and vertebrates, and antimicrobial peptides have become hot spots in immunology and molecular biology research. The contents of the study include: the separation and purification of antimicrobial peptides, analysis of amino acid sequences, relationship between protein configuration, and function of antimicrobial peptides [3, 4], application genetic engineering cloning and expressed antibacterial peptide gene, transforming synthesis antibacterial peptide Genes and animals and plants are transfected with bacterial peptide gene engineering, in which the study of insect antibacterial peptide gene engineering is most important [5, 6]. Small molecule peptides of antimony peptides or similar antibacterial peptides have been discovered in the biological boundaries, including bacteria, animals and plants and humans. This endogenous antibacterial peptide is synthesized by induction, plays an important role in the invasion of the body to resist the pathogen, and is considered to be an important defense ingredient lack of specific immune functional organisms. The antibacterial peptide has a broad spectrum bactericidal effect, and most of the Gram-positive bacteria have a strong killing effect, and some will work on Gram-negative bacteria and Gram-positive bacteria. For some fungi, native animals, especially for drug-resistant bacteria, and can choose to kill tumor cells to inhibit the replication of hepatitis B virus. 1. The classification of antimicrobial peptides has so far been 200 species from different organisms, and only more than 170 species are obtained from insects. Depending on the structure of the antimicrobial peptide, it can be divided into five categories: (1) antibacterial peptide of single-strandless hosteide (CYS), or a peptide consisting of two а-spirals connected to a roll-oriented curl. This class includes Enemy Cecropins, Magainins, and the like. Magainins was originally found in the skin of African jaws, which is the anti-infection of the pawl, which is divided under a certain environmental pressure and promotes the ingredient of the wound healing, composed of two tightly connected peptides, each peptide. There are 23 amino acids in the chain, and low concentrations can inhibit many bacteria and fungal growth [7]. (2) Antibacterial peptide rich in certain amino acid residues but does not contain CYS. Such as antibacterial peptides rich in proline (PRO) or glycine residues. The PRO content of 49% of the antimicrobial peptide PR39 isolated from the pig intestines [6]. The full order of the sheath peptide Coleoptericin and the hemiptericin is rich in GLY [8]. (3) Antibacterial peptide containing a disulfide bond, which is typically in the peptide chain C. Brevinins [9] produced in the skin cells of Tema skin cells. (4) There are two or more disulfide bonds, and there is an antimicrobial peptide having a beta folding structure. Such as the greenfly defensin, 6 Cys in the molecule form three molecular disulfide bonds, and the peptide chain C is a reverse parallel beta layer [10] of the proposed beta angle. Experiments have shown that disulfide bonds in molecules are critical in their antibacterial effects. (5) A peptide having antibacterial viability is derived from other known functions. 2. Effects of antimicrobial peptides 2. The antibacterial effect of antimicrobial peptide and its mechanism antibacterial peptide molecule can form an ionic aperture on the bacterial cytoplasmic membrane, resulting in a large amount of oil-soluble substance in the cell, and finally Resulting in bacteria death. The antibacterial peptide molecules are first bonded to the plasma membrane, and the hydrophobic sections and the amphiphilic α-helix in their molecules are also inserted into the plasma film, ultimately by mutual displacement between the membrane, the antibacterial peptide molecule aggregate to form an ionic passage, Lost the bacteria lost the membrane and death [10-14]. However, the experimental results derived from Gazit [15] showed that the antimicrobial peptide is only bonded to the surface of the unit membrane, and is not inserted into the film, and there is no passage. However, the action of the antibacterial peptide is a bacterial cytoplasmic membrane, as well as the effect of antimicrobial peptide, which leads to the increase in the permeability of bacterial cellular membrane, etc., which is also a traditional antibiotics such as antibacterial peptide and penicillin to bacteria. The effect mechanism is different.
2.2 Antibacterial peptide antiviral effects and mechanisms have found that blood lymphis of the peggy night moth has a significant inhibitory effect on six types of DNA and RNA virus, so that the infectivity of the virus is rapidly reduced, and this antiviral activity has broad spectrum Sex. Mariam [16] Tests showed that antibacterial peptides from pawls Magainins and other Magainins antibacterial peptides have the role of herpes zoster virus-HSV, and human neutrophil defensin (HNP-1) is also found to have a herpes virus. There is inhibitory effect. In addition, the beeducetin and the beewormins can also inhibit the gene expression of HIV HIV-1 at a tabular concentration, thereby inhibiting proliferation of HIV-1. This suggests that antifungal peptides have inhibitory effects on today's human tuberculosis - AIDS. 2.3 Anti-parasitic effects of antimicrobial peptides and their mechanism antibacterial peptides can effectively kill parasites that produce humans and animal parasitic diseases, such as malaria, Chagas disease, Leishmann disease. Currently, a synthetic flavin-bee toxin hybrid has a damage effect on Leishman's original flagepillar, and the role is a cytoplasmic membrane. It can quickly reduce H-OH permeability, destroy film potential, quality The membrane form is also damaged. Shahabuddin [17] found that insect antibacterial peptides had different effects on the development of plasmodium infected with mosquitoes, mainly caused significant damage to the focylactal period and child of Plasmodium. 2.4 Antibacterial peptide affects tumor cells and its mechanisms have been widely studied in anti-bacterial peptide killing tumor cells at home and abroad. It has found that antimicrobial peptides to cultivate cancer cells in vitro have mainly formed a hole on the cancer cell membrane. Air foaming occurs in mitochondria. The nuclear membrane boundary is unclear, and some nuclear membranes are damaged, and nuclear stain DNA is broken, and the synthesis of chromosome DNA is also subject to a certain degree of damage [18,19]. Through the study of tumor mice, antimicrobial peptides can significantly inhibit the accumulation of the abdomen of the ECA ascites tumor mice; the anttrosphaal ratio of S180 sarcoma and U14 cervical cancer is also reached from 30% -50% [20]. Antibacterial peptide can also mobilize the immune function of the body to resist cancer induction from humoral immunity. 3. Antibacterial peptide gene fusion expresses low natural production of antimicrobial peptides, synthesis, or from the body, the extraction step is complex, the yield is low, and the price of antimicrobial peptide is produced using genetic engineering technology. The alkaline amino acid carried by the antimony peptide makes it very sensitive to the protease, and the fusion expression strategy must be used to counteract the alkaline and reduce the toxicity of the host cell. Xie Wei and the like were synthesized from the antibacterial peptide cmIV gene, cloning it into the fusion expression vector of Golden Staphylococcus A protein and IgG affinity domain ZZ to obtain PEZZ318-CMIVV plasmid to convert E.COLIHB101 in this plasmid. The protein fused from ZZ-CMIV was obtained, and CMIV peptide was obtained after CBR. Li Xiulan et al [21] The amino acid sequence of natural antimicrobial peptide CMIV is 50% change, and the peptide gene fragment is synthesized according to the E.Coli preference, recombinantly to the sequencing carrier, and then recombine this piece to the expression vector PET28. Expression, fusion protein has the same biological activity as natural antibacterial peptides by CNBR. Wu Yai et al. To the upstream of the silkworm antimicrobial peptide D gene in the growth factor cDNA of the bovine fibril cells, successfully obtained in yeast, and the expression product has antigenicity of antibacterial activity and cow fibroblast growth factor. Kevin et al [22] HNP (Human Neutro Philpeptide 1) and CEME (Synthet Iccecropin / Melittinhybrid) respectively with GST (GLUTATHE-S-Trans ", ORRF, IGG combined sequence and spa (staphylococcal protein a) in E.COLI or S The fusion expression in .aureus, although the expression of the fusion of the SPA is achieved in S.Aureus, the expression yield is low; ZHANG et al [23] select the sequence of the REPA protein as the fusion of the antibacterial peptide, and inserted into Histag, etc. The sequence is used as a purified affinity site to achieve fusion expression in E.COLI. The antibacterial activity of fusion antifungal peptide obtained in study in CHRISTSNEN B is high than any of its donor antibacterial peptides. 4. Antibacterial peptide transgenic research Wang Zixing et al, the signal peptide sequence and antibacterial peptide Cecropin B gene or HHIVA a gene of the barley alpha-amylase constitute the chimeric gene, and the gene is introduced into potatoes, and the result of the signal peptide sequence CECROPIN B transgenic plants Delayed by blue blood, the condition index decreased.
YARUS et al. [24] transfer bovine gas antibacterial peptide gene into mice with a microinjection method, and the transgenic mouse is successfully expressed in the drive of the bovine tube antibacterial peptide gene control. The gas tube antimicrobial peptide, the bovine tube in the murder Antibacterial peptide has antibacterial activity against E. coli. Reed et al. Synthesis and subsequent inhibitory effects of Burda bacillus were studied by IL-2 promoter / enhancer control transgenic rats. Reed [25] constructed such a DNA fragment: ShiVala fragment, SV40 polyadenated / shear signal peptide gene fragment, which was added to the rat IL-2 gene 5 'side-593- 110 region. This fusion gene was injected into a fertilized egg (microinjection) in the presence of a fertilized egg. RT-PCR Detection: Two-Series transgenic rats, when their spleen lymphocytes are placed in ConA (karmetan proteins, an antigen inducement), which can induce mature ShiValam RNA. When inoculating with a certain amount of Buchenobacillus, there were two straits of mice attacked. Four weeks later, there were fewer non-transgenic rats (P <0.05) in the transgenic murine spleen tissue (P <0.05). David Winger et al. [26] placed the gene encoding Ceropin or Melittin under the promoter of MLV (rat white blood disease virus), transfected into EJ cells (human bladder cancer cells), then injected these cells into nude mice, discoverable these Tumor cells stop growing or growing David Winger et al. PCR amplification, prepromelittin (PPM premeutum), premelittin (PM premethell) and precelittin three nucleic acid pieces, all of which are placed in MLV promoter The constructing a fusion gene is transfected into EJ cells. After three types of EJ cells were injected into nude mice, the 50D tumor growth was measured, and the EJ cell (control group) of an antimicrobial peptide gene fragment was 70%, and the EJ cells with CECROPIN gene fragments only 39%, PPM is 50%, PM is 65%, which inhibits the effect of tumors. 5. Application Prospects of antibacterial peptides At present, most of the plant antimicrobial peptides are separated from plant seeds, which can protect plant tissue and seeds from fungal pathogens, but plant antimicrobial peptides have no inhibitory activity against most bacteria. Therefore, relying on genetic engineering method to transform crops with other eukaryotic antibacterial peptide genes, cultivate new varieties of anti-disease is a hot spot in current domestic and foreign research. Animal antibacterial peptide and interferon, the complement is an important part of the body non-specific natural defense system. When the body is damaged or the pathogenic microbial invasion, it can quickly produce antimicrobial peptides to kill intruders, which has little effect on normal eukaryotic cells. In addition, since the synthesis rate of antimony peptides is very fast (assuming the peptide bond synthesis rate of ribosome is constant, the production of antimicrobial peptides is more than 100 times more than IgM), [27] and the spread of the small peptide is larger protein and immunocytes. A more rapid, more flexible, so Boman has pointed out that antibacterial peptide is an ideal first-line defense for the body. Compared to ordinary antibiotics, antibacterial peptides "antibacterial spectrum" is broader, in addition to antibacterial, some antimicrobial peptides can also act in fungi, protous, enveloped viruses and cancer cells (selective effect on cancer cells) Related to changes in its cell skeleton) while accelerating immunization and wound healing process. This indicates that antibacterial peptides have good application prospects in treatment and preventive cancer and antiviral, anti-infection. More importantly, due to the abuse of antibiotics, it is necessary to find new antibacterial agents due to the abuse of antibiotics. Antibacterial peptide This kind of substance obtained from organisms happens to have a unique antibacterial mechanism, which is not like a general antibiotic to play a role in blocking biological synthesis of biological macromolecules, so it is very promising to develop a new type of broad-spectrum efficient. Antibacterial drugs. As the research work is further in-depth, it is foreseeable that antimicrobial peptides and their genetic projects will play more important roles in medical, health, food industry and agriculture. In addition, some antibacterial peptide molecules contain D-amino acids, which also provides an ideal mode system for studying how D-amino acids provide a synthetic polypeptide on ribosome. 6. Research prospects and existence of antimicrobial peptides are an important part of the mammalian defense system, which has the advantages of thermal stability, good water soluble, broad-spectrum and even can kill fungi, protracain, etc., and many antimicrobial peptides heaters at 100 ° C It can still maintain a certain vitality under 10min conditions, and there is strong resistance to larger ionic strength and lower or higher pH, and there is almost no effect on eukaryotic cells, only acting on prokaryotic cells and lesions. Early nuclear cells, and antibiotics are completely different by blocking macromolecular biosynthesis, and the diseased source is not easy to produce drug resistance, thereby showing its unique research and application value.
In the past 20 years, people have carried out the theory and application of insect antibacterial peptides, but there are few reports on the application of livestock antimicrobial peptide gene engineering. From the nature of the mammalian antibacterial peptide, it shows that it has the following aspects of research and application prospects in animal husbandry production. Research Prospects and Existence 6.1 Pharmaceutical Prospects With the extensive and long-term use of traditional antibiotics, many pathogenic bacteria have a drug resistance, while antibacterial peptides with broad-spectrum antibacterial and unique antibacterial mechanisms are clear in this regard. Application research is a significant advantage. With the relationship between antibacterial peptide structure and activity, antibacterial peptide action mechanism and its gene expression regulation mechanism have been deepened, designing an efficient, antibiotic peptide that is conducive to human health is completely feasible. 6.2 Transgenic research and application piglet diarrhea, dairy breast inflammation, various viral diseases such as swine fever, chicken new city evolution, etc. have always been a tricky disease, which is not conducive to the development of animal husbandry. Drawing on the successful insect antibacterial peptide transgenic engineering, such as transgenic mosquitoes, transgenic potatoes, transgenic rice, etc., the specific antibacterial peptide gene is transferred to livestock-specific cells, thus generating new varieties of anti-disease, is not losing a development of animal husbandry production New ideas, far-reaching prospects. 6.3 Antibacterial peptide gene expression regulation and antibacterial peptide additive studies have shown that [28] antibiotic additives have severely undermined microbial balance of animal intestines, and they are easily residual in animals, which seriously affects the quality of livestock products and human health. Production of environmentally friendly antimicrobial peptide additives, or, the expression of antimicrobial peptide genes is further studied by the expression of antimicrobial peptide genes by diet factors. However, due to the small antibacterial peptide molecules, there is a certain difficulty in separation and purification, so natural resources are limited. The chemical synthesis and genetic engineering method obtaining antimicrobial peptide is the primary means, but the chemical synthesis of antibacterial peptide is high, and the genetic engineering directly expresses antibacterial peptide genes in microorganisms, which may be harmful to hosts without acquisition. Therefore, further study on the structure, moisture relationship and mechanism of antifungal peptides. 7. Conclusion antibacterial peptide is a series of immune response reactions produced by organisms in the inactivara. It has emerged for people to find ideal antibacterial drugs, especially many of the antibiotics, produce drug resistance. Therefore the antibacterial peptide has a huge application potential. The development of genetic engineering technology has greatly promoted the research and development of antimicrobial peptides, and it is possible to produce a lot of production through the cloning of antimicrobial peptide gene. Although the antimicrobial peptide is still not directly applied to the aquaculture industry, the mechanism of the antimicrobial peptide is less likely to produce resistance to the continuous in-depth of research work, and it can believe that antimicrobic peptides will play an important role in animal breeding and improving the quality of animal products. effect. Reference [1]. Hancock Rew.The Lancet, 1997,349 (9049): 418 [2] .steinerhd, Hultmarka.
, ENGSTR¨OMH, et al.Sequence and specificity of twoantibacterial two antibacterial proteinsin volvedin in sectimmunity [J] .Nature, 1981,292:. 246-248 [3] .CAMMUEBP, DEBOLLEMF, SCHOOFSHM, et al.Gene-encoded antimicrobial peptides from plants [J] .Ciba Found Symposium, 1994,186: 91-106 [4] .LAMBERTYM.Insectimmunity is olation from the lepidopteeran Heliothis virescens of a novel insect defens in with potent antifungal activity [J] .JbiolChem, 1999. , 274: 9320-9326 [5]. Li Wenchu, Huang Natural. Insect antibacterial peptide and its genetic engineering, transgenic animals [M]. Guangzhou: Guangdong Science and Technology Press, 1996.118-128. [6]. Zheng Qing, Bao Shixiang, Yao Yuhua, et al. Design and synthesis of new antibacterial peptide gene design, synthesis and expression of I --- hybrid antibacterial peptide gene in yeast [J] .Journal of South China University of Technology, 1998,26 (3): 60-63. . 9] Chen Luhou, Wang Jinxing. Progress of Biological Engineering, 1999, 19 (5): 55 ~ 59. [10]. 贤 才, Hu Fusan, et al. Department of Life, 2001, 21 (5): 357 ~ 359. 11] .Marchini D, et al. [J] .insect Biochem Mol Biol, 1993,23 (5): 591-598. [12] .radermacher SW, ET Al. [J] .jneurosi Res, 1993, 36 ( 6): 657-662. [13] .lockey TD ER Al. [J] .eur J Biochem, 1996,236 (1): 236-271. [14]. Saberoal G ,. et al. [J] .biochem BioPhys Acta, 1994, 1197 (2): 109 -131. [15]. Gazit E, ET Al. [J] .biochem IS Try, 1994,33 (35): 10681-10692. [16]. Mariam E. et al. [J] .international J of AntiMICRobial Agents, 1999, 13: 57-60. [17]. Shahabuddin M, et al. [J] .Experimental ParasitoGy, 1998,89 (1): 103-112. [18]. Wang Fang, et al. [J] Progress in Biochemistry, 1998,25 (1): 64-67. [19]. Jia Hongwu, et al. [J]. Sericulture Science, 1996, 22 (4): 62. [20]
