Research Summary:

Antimicrobial peptides are the main active components of the natural defense system that exists in many organisms in nature against the invasion of microorganisms such as exogenous fungi, bacteria and viruses. This article summarizes the progress of biomedical research on antimicrobial peptides, hoping to help more researchers.

Antimicrobial peptides show a broad antibacterial spectrum, unique and complex antibacterial mechanism, and are not easy to produce drug resistance. They are considered to be the best drugs for multidrug resistant bacteria. Many non-human antimicrobial peptides have problems such as immunogenicity, hemolytic reaction and short half-life.

On the basis of the original antimicrobial peptides, researchers have improved the activity of antimicrobial peptides, reduced toxicity, and simplified the preparation process through different modifications. At the same time, there are also scientific researchers who continue to study the mechanism of action of antimicrobial peptides, in order to provide more feasible references for the discovery and design of antimicrobial peptides.

Key words: antimicrobial peptides, peptide modification, antibacterial mechanism

In the process of searching for antibacterial active substances, scientists have found that some active substances in the natural immune system of some organisms are mostly small molecular peptides. Although the sequences of these active peptides are very different, they also have many commonalities. For example, usually containing 5 to 100 amino acids, rich in Arg and Lys, positively charged, and amphipathic, they are now collectively called antimicrobial peptides (AMPs).

Searching the antibacterial peptide database shows that as of December 2015, more than 2,600 antibacterial species have been identified . The antimicrobial peptide library (APD2684) contains antimicrobial peptides from six fields (266 bacteriocins from bacteria, 4 from archaea, 8 from protists, 13 from fungi, 329 from plants, 2018 derived from animals)

According to different objects of action, it can also be divided into: antibacterial peptides (antibiofilms), antiviral peptides (anti-HIV), antifungal peptides, parasitic peptides (antimalarial), anticancer peptides, antibiological peptides, insecticidal peptides, spermicidal peptides Peptides, chemotactic peptides, antioxidant peptides, protease inhibitors, etc.

Antimicrobial peptides have a wide antibacterial spectrum and are not easy to cause drug resistance. They are considered as an ideal antibacterial active substance and are expected to solve the problem of drug-resistant bacteria. In addition to killing bacteria, antimicrobial peptides can also be used in the treatment of cancer and septic shock.

People’s research on antimicrobial peptides is getting deeper and deeper, and the understanding of antimicrobial peptides is clearer. In recent years, while people have continuously discovered natural antibacterial peptides, they have also analyzed and summarized known antibacterial peptides. On this basis, scientists have used methods such as modification, recombination, and artificial peptide synthesis in peptide laboratories, to improve the activity of antimicrobial peptides, reduce toxicity and so on.

Modification Method of Antimicrobial Peptide

Antimicrobial peptides are generally small molecular peptides, which can easily enter the body and play a role. However, due to the presence of various proteases in the body, the half-life of antimicrobial peptides must be considered. Otherwise, it is necessary to increase the dose or give multiple doses in a short period of time. Drugs, which will inevitably fail to meet the requirements of effective and convenient medication.

In order to solve the problem that antimicrobial peptides are easy to degrade, there are currently various modification forms, such as linking fatty acids, amino acid fluorination, and replacing L-amino acids with D-amino acids. From the essence of modification, it can be divided into two categories: chemical modification and biochemical modification.

1. Chemical Modification of Antimicrobial Peptides

The classical theories and chemical reactions of chemistry guide the continuous improvement of people’s lives and the continuous development of industrial production. Chemical modification of many medicinally active substances is also an important idea in the field of pharmaceutical research.

 For example, in order to change the water solubility of the original substances, reduce the various toxic and side effects of metabolites on the body, etc. This kind of modification is not limited to the modification of chemical drugs by chemical groups, but also the modification of biological drugs is very common.

2. Biochemical modification of antimicrobial peptides

The biochemical modification of antimicrobial peptides mainly uses molecular biological means to change the biochemical composition and characteristics of the original antimicrobial peptides, so as to obtain peptides with better medicinal activity. Or optimize the expression system of antimicrobial peptides with good medicinal effects to reduce the cost of medicinal use.

Mechanism of Action of Antimicrobial Peptides

While constantly discovering new antimicrobial peptides, people are also committed to the research on the mechanism of action of antimicrobial peptides in order to better provide a more scientific basis for the design of antibacterial drugs. 

From the initial research on the mechanism of action of antimicrobial peptides through transmission electron microscopy to the current techniques such as isothermal titration calorimetry, the understanding of the mechanism of action of antimicrobial peptides has become more and more in-depth.

Research Prospects of Antimicrobial Peptides

The study of antimicrobial peptides is required for the threat of multidrug-resistant bacteria to human health, and is also a product of the development of life science and technology. 

Whether it is the research on the isolation and identification of antibacterial active substances from various organisms and their metabolites, or various components of the body, or the research on the mechanism of action of identified or synthesized antimicrobial peptides, or on the medicinal value High industrial production research of antimicrobial peptides is an essential part of antimicrobial peptides for human use. This makes antimicrobial peptides have broad prospects in the field of drug-resistant bacteria.

---

About the Author:

Shuai Lv, graduated from the School of Pharmacy of Southwest University, engaged in pharmaceutical research and development, organic synthesis of peptides for 8 years, currently working as a researcher of antimicrobial peptides in Omizzur Peptide Laboratory. Hope my research here can help more people.

You may visit our laboratory and check peptide research here: www.omizzur.com