Why and how will it be a threat?
Nearly two centuries ago, Louis Pasteur revealed through double sodium-ammonium salt of tartaric acid crystals that molecules of the same composition seemed to be mirror images of each other. Each molecule had one of two distinct forms, either rotated polarized light clockwise or counterclockwise. Pasteur’s discovery laid the foundation of the chirality of molecules, or in other words, a molecule’s unique “handedness” (1). Despite having identical chemical formulas, chiral molecules have a non-superimposable mirror image. Similar to the right hand being similar yet evidently distinct from the left hand, a non-superimposable mirror image refers to how molecules will not match up when overlapped; they are asymmetric. Pasteur thus proved that molecules of the same composition can be structurally distinct from each other. Pasteur named molecules either “L” configured for leavus meaning left in Latin, or “D” configuration for dexter meaning right in Latin.
Mirrored molecules
Research soon found that these two configurations of a molecule are found in base codes that all forms of life follow. DNA is in the D, or right-handed form, whereas amino acids are in the L, or left-handed form. This pattern is crucial to nearly any process within the cells and even to how our body works. All molecules are chiral and have a certain chirality. A given molecule’s structure relies on its unique chirality, meaning that it will only interact with molecules of that same chirality. This tendency is seen with all of our body’s molecules.
Pasteur’s experimentation on the chirality of molecules and how they work opened a new possibility: mirror life. Mirror life hypothetically reverses the natural chirality of L and D form to their opposing handedness. Mirror organisms would be synthetically composed by reversed L formed DNA and D formed amino acids. Today, researchers across the world are attempting to actuate mirror life to create synthetic organisms.
Theoretically, there could be a supposed benefit from a reverse-oriented chirality. An advantage to mirror life would be that living organisms in the current world would be unable to interact with these unfamiliar organisms. Thus, researchers in the medical field are interested in programming ensuring drug safety through biological molecules being unable to interact with each other.
For example, mirror life molecules are more resistant to natural degradation than natural molecules, as they would be unchanged by enzymes that are meant to break down natural molecules. This prolonged period of activity is likely to have longer effects of the drug. The pre-existing shorter half-life of most drugs that follow natural chirality would be mitigated. This same pattern can be applied to reduce side effects. Many therapeutic drugs oftentimes end up affecting molecules beyond the targeted molecule due to drugs being unable to be perfectly selective. On the other hand, reverse mirror molecules will have a much smaller potential of affecting molecules beyond the target molecule, as naturally chiral molecules are unable to interact with it (3). Recently, scientists have been able to chemically synthesize mirror proteins that are D formed instead of its natural L form. So far, these proteins have shown positive results in therapeutic drugs. For example, d-peptides that help treat Alzheimer disease and cancer that are more effective than natural l-peptides because they are less degradable (2).
Mirrored molecules
Yet, a group of nearly 40 renowned biologists came out with a warning to the community, asking to halt further research efforts to create mirror life before it becomes too risky, as it will initiate an “unstoppable pandemic.” The warning, entailed in a 299-page technical report, claimed that scientists would successfully create mirror life in the next few decades. However, mirror life allegedly has the power to collapse ecosystems with deadly effects on a global scale, according to Nobel-prize-winning chemist Jack W. Szostak. Since all organisms are adapted to the natural chirality, it also means that mirror organisms can have the power to evade such restraints. For example, in the human immune system, to fight off pathogens, they must be first detected by sensors. However, these sensors only work on D configured DNA and L configuration proteins. If mirror molecules will not go through this same checks and balance system of molecules, the cell can spread throughout the body with little resistance, meaning that it could easily become fatal (5). This similar idea applies to any existing antibiotics. If a pandemic-like fatal outcome does become true to word, mirror cells can kill off not only humans, animals, plants, or any living organism. Not to mention, ecological damage could occur (4).
Thus, scientists propose that to avoid this uncontrollable pandemic, further research about mirror life should halt. While an antibiotic of mirror life could be created, scientists predict that it will be much after the expected creation of mirror life.
References
- DeGrado, W. F. (2018, January 29). Method to generate highly stable D-amino acid analogs of bioactive helical peptides using a mirror image of the entire PDB. PNAS. Retrieved from https://www.pnas.org/doi/10.1073/pnas.1711837115
- Hong Kong Baptist University. (202, May 12). Scientists eliminate drug side effects by manipulating molecular chirality. Retrieved from https://www.sciencedaily.com/releases/2020/05/200519101320.htm
- University of Edinburgh. (2024, April 24). New method could cut waste from drug production. Retrieved from https://www.ed.ac.uk/news/2024/new-method-could-cut-drug-production-waste#:~:text=Chemical%20method,a%20process%20 called%20 asymmetric%20 synthesis.
- Service, R. F. (2023, June 13). ‘Breakthrough’ could explain why life molecules are left- or right-handed. Retrieved from https://www.science.org/content/article/breakthrough-could-explain-why-life-molecules-are-left-or-right-handed#:~:text=In%201848%2C%20French%20chemist%20Louis,%2D%20and%20 left%2 Handed%20 molecules.
- Zimmer, C. (2024, December 12). A ‘Second Tree of Life’ Could Wreak Havoc, Scientists Warn. The New York Times. Retrieved from https://www.nytimes.com/2024/12/12/science/mirror-life-microbes-research.html