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First, the source is different
Antibiotics are a class of secondary metabolites produced by microorganisms (including bacteria, fungi, actinomycetes) that are resistant to pathogens or other activities during their life. For example, secondary metabolites produced by penicillin-derived Penicillium, the colistin sulfate is derived from secondary metabolites produced by myxobacteria. Antimicrobial peptide, also known as host defense peptide, refers to a kind of antibacterial active small molecule polypeptide substance which is induced by in vivo immunity and is first discovered in insects and then in various organisms. Found, including bacteria, plants, animals and even humans. The antimicrobial peptides produced by some microorganisms are primary metabolites and are directly produced by organisms.
Second, the production method is different
Antimicrobial peptides are synthesized by gene coding, from DNA to RNA to proteins (polypeptides), so the amino acids in all antimicrobial peptides are 20 common amino acids. That is, each adjacent three nucleotides in the messenger RNA molecule is grouped together to represent an amino acid during protein synthesis. For example, AAA is lysine and AUG is methionine. Most of the antibiotics are produced by enzymatic reactions. It involves the action of many synthetases, hydrolases, transferases, etc., combining some chemical groups to form complex structures. Even though some peptide antibiotics have undergone a large number of enzymatic reactions, many peptide antibiotics have difficulty in having a clear amino acid sequence because of the large number of amino acid derivatives or rare amino acids. If the bacitracin consists of 9-12 amino acids and its derivatives, and there is a modification of the thiazole ring, it is difficult to determine the amino acid sequence. For example, colistin sulfate consists of 10 amino acids, 6 of which are diaminobutyric acid, a rare amino acid, that is, a non-coding amino acid, and a non-amino acid structure of methyloctanoyl, so it is difficult to determine Amino acid sequence. Most of these structures are produced by enzymatic reactions.
Third, the immune function of the body is different
The antibacterial peptide is a host defense peptide, which plays an important regulatory role in host innate immunity and can improve the body's non-specific immunity. For example, cecropin antibacterial peptide can improve the non-specific immunity of the body by increasing the ratio of CD4+ and CD8+. Many antibiotics can not improve immunity, but also have an inhibitory or damaging effect on immunity. For example, chloramphenicol has a strong destructive effect on bone marrow hematopoietic function, thereby reducing the production of immune cells. Because the antibacterial peptide is an anti-exogenous pathogen produced by the innate immunity of the body, in addition to inhibiting and killing the bacteria, it has a certain inhibitory effect on fungi, viruses and protozoa, and the antibacterial spectrum of different antibacterial peptides is different. Antibiotics, which mainly kill bacteria-based microorganisms, have no effect on the virus.
Fourth, the mechanism of action is different
Most antibiotics have specific sites of action, such as quinolone antibiotics inhibiting DNA gyrase, tetracycline antibiotics inhibiting the ribosomal 30S subunit, penicillin competes with cell wall D-alanyl-D-alanine, and inhibits cell wall synthesis. The main role of antibacterial peptides is on the cell membrane of bacteria, which kills bacteria by changing the permeability of cell membranes, and is not easy to produce drug resistance.
As can be seen from the above four points, there is an essential difference between antibiotics and antibacterial peptides. It is even more difficult to confuse antibacterial peptides with peptide antibiotics. As an alternative to antibiotics, the development and application of antimicrobial peptides are currently global antibacterial agents, adjuvants and immunizations. The hotspots of enhancer research have attracted a large number of biological companies to continue research. With the advancement of technology, the phrase "antibacterial peptides for the benefit of all mankind" will gradually become a reality.
(Article source: National Feed Engineering Technology Research Center Zhongnong Yingtai Group Technology Department)
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