How did life begin? How did chemical reactions on the early Earth create complex, self-replicating structures that developed into living things as we know them? According to one school of thought, before the current era of DNA-based life, there was a kind of molecule called RNA. RNA-which is still a crucial component of life today-can replicate itself and catalyze other chemical reactions.
Chemists like me are trying to recreate the chain of reactions required to form RNA at the dawn of life, but it’s a challenging task. We know whatever chemical reaction created ribonucleotides must have been able to happen in the messy, complicated environment found on our planet billions of years ago.
These are reactions that produce chemicals that encourage the same reaction to happen again, which means they can sustain themselves in a wide range of circumstances. Autocatalytic reactions play crucial roles in biology, from regulating our heartbeats to forming patterns on seashells.
A chemical reaction called the formose reaction, first discovered in 1861, is one of the best examples of an autocatalytic reaction that could have happened on the early Earth. In essence, the formose reaction starts with one molecule of a simple compound called glycolaldehyde and ends with two.
A reaction between glycolaldehyde and formaldehyde makes a bigger molecule, splitting off fragments that feed back into the reaction and keep it going. Once the formaldehyde runs out, the reaction stops, and the products start to degrade from complex sugar molecules into tar.
The formose reaction shares some common ingredients with a well-known chemical pathway to make ribonucleotides, known as the Powner-Sutherland pathway. The formose reaction is notorious for being “Unselective.” This means it produces a lot of useless molecules alongside the actual products you want.
In the study, researchers tried adding another simple molecule called cyanamide to the formose reaction. The reaction still does not produce a large quantity of ribonucleotide building blocks. What’s interesting about our study is the integration of the formose reaction and ribonucleotide production. The lab is currently optimizing this procedure in the hope we can manipulate the autocatalytic reaction to make common chemical reactions cheaper and more efficient, and their pharmaceutical products more accessible.