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New class of bacteria busting antimicrobials

Polypeptides are short protein chains and the attack bacteria by perforating the bacterial membrane. This process of “hole punching” happens multiple times, until the bacterial cell breaks up. The technical term is “membrane disruption.” The activity can be confirmed using such techniques as neutron and X-ray diffraction, and fluorescent dyes.

Research has shown that polypeptides can be engineered with a positively charged shell. This charge allows them to progress in body fluids and prevents them from interacting with other proteins. The charge serves a secondary function, allowing the polypeptide to be attracted to the negatively charged bacterial cell membranes.

The new design of polypeptides incorporates a spiral design, according to the research note, which leads to a slightly twisted rod-like structure. This shape and relative hardness allows the polypeptide to more readily break holes into the bacterial membrane.

The advantage of this type of antimicrobial is that it is, in theory, difficult for a bacterium to develop resistance to it. Other antimicrobials (such as antibiotics) target specific areas of the bacterial cell through chemical interaction. However, the polypeptides work on the basis of causing structural damage.

As a way of building effectiveness, it may be possible to pre-load the polypeptides with other antimicrobial agents in order to increase effectiveness. The process of breaking into the bacterial cell could allow these antimicrobial agents to by-pass bacterial cell defenses, even in cases where the type of bacteria has developed resistance to the antimicrobial agent.

The research was led by Professor Jianjun Cheng, and the findings are published in the journal Proceedings of the National Academy of Sciences. The research paper is titled “Helical antimicrobial polypeptides with radial amphiphilicity.”

Written By

Dr. Tim Sandle is Digital Journal's Editor-at-Large for science news. Tim specializes in science, technology, environmental, and health journalism. He is additionally a practising microbiologist; and an author. He is also interested in history, politics and current affairs.

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