When did life start? How did sophisticated, self-replicating structures
emerge from chemical interactions on the early Earth to become living
organisms as we know them?
One school of thought holds that there existed a type of molecule known as
RNA (or ribonucleic acid) prior to the current era of life based on DNA. RNA
has the ability to duplicate itself and catalyze other chemical events,
making it an essential component of life as we know it today.
However, the building blocks of RNA molecules are smaller units known as
ribonucleotides. How would these components have come together to produce
RNA after forming on the primordial Earth?
It's a difficult effort for chemists like myself to reproduce the series of
processes needed to make RNA at the beginning of life. We know that the
complex and chaotic environment on our planet billions of years ago must
have allowed for the chemical process that produced ribonucleotides.
I've been researching the possibility that "autocatalytic" processes were
involved. These reactions can persist under a variety of conditions because
the chemicals they create promote the occurrence of the same reaction
again.
My coworkers and I have just incorporated autocatalysis into a well-known
chemical pathway to produce the building blocks of ribonucleotides, a
process that may have reasonably occurred given the simple molecules and
complicated environment present on the early Earth.
The response of Formose
In biology, autocatalytic processes are essential for anything from
controlling heart rate to creating patterns on seashells. The process of
life itself, in which a single cell uses its surroundings to generate two
more by absorbing nutrients and energy, is really a very intricate instance
of autocatalysis.
One of the better instances of an autocatalytic process that might have
occurred on the early Earth is the formose reaction, which was originally
identified in 1861.
Glycolaldehyde is a simple chemical consisting of hydrogen, carbon, and
oxygen. The formose reaction essentially begins with one molecule of this
substance and finishes with two. The formaldehyde molecule, another simple
chemical, is essential to the mechanism's operation.
Glycolaldehyde and formaldehyde mix to generate a larger molecule, which
then breaks up into smaller pieces that feed back into the reaction to
continue it. But as soon as the formaldehyde runs out, the synthesis halts
and the complicated sugar molecules begin to break down into tar.
The Powner–Sutherland route, a well-known chemical mechanism for producing
ribonucleotides, and the formose reaction have several similar constituents.
To be fair, nobody has attempted to make the connection between the two up
until now.
The "unselective" nature of the formose reaction is well-known. This
implies that in addition to the desired products, it also generates a large
number of worthless molecules.
An autocatalytic detour on the ribonucleotide route
In our investigation, we experimented with cyanamide—an additional basic
molecule—adding to the formose process. This allows some molecules formed in
the process to be "siphoned off" and converted into ribonucleotides.
Even yet, the process does not yield a significant amount of ribonucleotide
building blocks. The ones it does generate, though, are less prone to break
down and more stable.
Our study's combination of the ribonucleotide synthesis with the formose
reaction is intriguing. Prior research has examined each independently,
which is consistent with the way chemists typically approach the synthesis
of compounds.
Chemists typically steer clear of complexity in order to maximize a
product's quantity and purity. This reductionist methodology, however, may
keep us from looking into the dynamic connections between various chemical
pathways.
These interactions are undoubtedly the link that connects biology and
chemistry since they occur everywhere in the real world outside of the
lab.
applications in industry
The industrial sector can also benefit from autocatalysis. Another
byproduct of the formose reaction that is produced when cyanamide is added
is a substance known as 2-aminooxazole, which is utilized in both medicinal
and scientific research.
Glycolaldehyde, a costly substance, and cyanamide are often used in the
conventional synthesis of 2-aminooxazoles. Should the formose reaction be
employed, a minimal quantity of glycolaldehyde will be required to initiate
the reaction, hence reducing expenses.
In an effort to control the autocatalytic reaction and increase the
affordability and efficiency of common chemical processes as well as the
accessibility of medicinal goods, our lab is now refining this process. We
believe it may still be meaningful even if it might not be as significant as
the genesis of life itself.
Quoc Phuong Tran, PhD Candidate in Prebiotic Chemistry, UNSW Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.
