Searching for the origins of life on Earth

21/10/2024

By Laura Filloy (GCiencia).

Where were the first molecules formed? Where did the molecules that gave rise to life originate? And how did they make their way to Earth? These are three questions that remain unanswered—at least for now. A team from the Center for Research in Biological Chemistry and Molecular Materials (CiQUS) has just published a study in Science Advances that takes a step forward in understanding how molecules were formed in the interstellar medium. These findings could shed light on the formation of prebiotic molecules—precursors to life as we know it.

This work is the cornerstone of a broader, more ambitious investigation. The CiQUS team developed a computer program capable of automatically searching for reaction mechanisms of molecules, and they decided to apply it to interstellar chemistry. In other words, they set out to uncover the pathways that molecules follow to form in the interstellar medium. Specifically, the researchers studied the formation pathways of benzene and benzyne—two compounds toxic to humans but of great industrial interest. "We chose to study them because they can be produced in the lab and are stable! But at the same time, they have also been detected in the interstellar medium, where the conditions are very different from those in a laboratory," explains Marta Castiñeira, the study's lead author.

"It’s fascinating that benzene and benzyne, which require high temperatures and pressures to form on Earth, are also generated in the interstellar medium and can survive there, where temperatures are so low," says Castiñeira, a postdoctoral researcher at CiQUS. To understand this process, molecular modeling and automatic reaction search methods were used, particularly a program developed at USC called AutoMeKin. "We gained a comprehensive perspective of the processes that could give rise to benzene and benzyne," the researchers note.

The selection of these two compounds, despite their limited importance to humans, was not arbitrary. "They’re not really relevant for people because they form during combustion processes," clarifies Castiñeira. However, the significance of this study lies not in the result itself but in the future research possibilities it opens. "If we can accurately describe these molecules, we might be able to extend this idea to others that are relevant to the origin of life, such as amino acids," Castiñeira suggests.

The CiQUS researcher confirms that the team is already working in this direction and emphasizes that this approach could be key to understanding the origin of life. "This study supports the panspermia hypothesis, which suggests that the first prebiotic molecules—precursors to life on Earth—may have formed in the interstellar medium and been transported by meteorites that impacted our planet," she asserts. However, more research is needed to continue opening pathways that will allow us to better understand interstellar chemistry.

This work, led by Antonio Fernández Ramos' team, enabled the selection of processes occurring under the "harsh conditions" of the interstellar medium. As Castiñeira explains, "with extremely low temperatures and near-zero pressure." The use of automated reaction mechanism search methods allowed the team to generate hundreds of possible formation pathways for benzene and benzyne. Now, the CiQUS team is focusing its research on the formation of amino acids in the interstellar medium—compounds that are fundamental to understanding life as we know it.

Reference
Marta Castiñeira Reis et al.,Comprehensive computational automated search of barrierless reactions leading to the formation of benzene and other C6-membered rings.Sci. Adv.10,eadq4077(2024). DOI:10.1126/sciadv.adq4077

 

Fernández-Ramos research group at CiQUS labs.