This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Swimming in the blood, sweat, cells and tears of every human are small proteins known as peptides. Many peptides can kill bacteria on contact, yet the bacteria never seem to evolve resistance to them.
Mass-produced peptides could become a new type of antibiotic that evades resistance, but they are challenging to work with. They are short-lived and expensive to synthesize. In a new paper, researchers at Stanford School of Engineering describe how they trained an AI model to scour millions of other potential molecules—polymers—for candidates that mimic the mechanisms peptides use to kill bacteria so effectively.
The paper is published in the journal Matter. These new polymers also share peptides' ability to overcome or escape the microbial resistance that plagues many traditional antibiotics, bringing hope to the public health community. Millions worldwide die each year from drug-resistant microbial infections.
"Antimicrobial peptides are chemically able to get very close to and disrupt the cell membrane, killing the bacteria," explained Shoshana Williams, a former graduate student in chemistry at Stanford Engineering who recently earned her Ph.D. working on this challenge. "Importantly, they don't need to get inside the cell to work, like a typical drug would. Nor do they work on one specific protein or pathway, like drugs do." The key to evading resistance is that these new molecules use a physical, rather than biochemical, pathway to attack the bacteria.
"The peptides permeabilize the microbes … they literally rip holes in the cell membrane to kill them," said Eric Appel, a professor of materials science and senior author of the study. "It's much harder for a bacterium to change the entire lipid structure of its membrane or the electrical charge of its surface than to learn to reject a chemical drug or turn off its narrow pathway." The researchers are quick to point out that the new chemicals are not synthetic peptides but rather a different type of molecule altogether: polymers. These long, chain-like molecules are easier and cheaper to synthesize than peptides and do not degrade easily, enabling global distribution and access to low-resource communities.
Polymers are also "super safe," Appel added. The researchers built a library of 1.7 million potential polymer candidates to choose from—an overwhelming number to investigate manually—so they did it computationally. They developed a new model that predicts the chemical properties of the polymers based on their chemical structures and identifies those that have similar antimicrobial characteristics to the peptides.
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