Their experiments proved that the key chemical reactions that support life these days were possible 4 billion years ago.
All aerobic organisms, from bacteria to humans, use it in the process of cellular respiration. Previously, scientists believed that the first life forms were characterized by the Krebs cycle, similar to the modern one. However, the molecules involved in it are too fragile and probably could not exist 4 billion years ago. To solve this problem, the researchers determined which of the molecules that existed on the early Earth could participate in the Krebs cycle.
A new study showed that two non-biological cycles - a cycle of 4-hydroxy-2-ketoglutarate and a malonate cycle - can be combined, forming an earlier version of the Krebs cycle.
According to the authors of the work, as the appearance of biological molecules, for example, enzymes, they could replace non-biological analogs, forming the Krebs cycle known to us. Thus, modern metabolism had a non-biological predecessor, which as a result of evolution became more complex and effective.