Glyoxylate: The simple chemical that could hold the key to early life forms
Two prominent origin-of-life chemists from Scripps Research and the Georgia Institute of Technology have put forth a novel hypothesis regarding the source of life’s first sugars that were essential for the evolution of life on early Earth.
Today, a group of chemists from Scripps Research and the Georgia Institute of Technology published a paper in the journal “Chem,” proposing that glyoxylate (C2HO3–), a simple chemical that may have existed on Earth prior to the emergence of life, could have been involved in the formation of essential sugars necessary for the creation of early life forms. This suggests that glyoxylate may have played a crucial role in the origins of life on Earth.
“We show that our new hypothesis has key advantages over the more traditional view that early sugars arose from the chemical formaldehyde,” remarks Ramanarayanan Krishnamurthy, PhD, a professor in the Department of Chemistry at Scripps Research.
The objective of origin-of-life chemists is to elucidate the origins of the essential molecular building blocks and reactions required for the emergence of life, and how they could have developed from the basic chemicals that were believed to be present on the prebiotic Earth. The ultimate goal of this field is to unravel the fundamental mystery of how our planet became a hub of life. Additionally, the findings of this research have practical implications for a diverse range of scientific domains such as atmospheric science, geology, synthetic biology, and astrobiology, where it helps in the quest to discover life on other planets.
To account for the availability of biological molecules in the origin-of-life chemistry, three primary classes need to be considered: amino acids constituting proteins, nucleobases composing the building blocks of DNA and RNA, and sugars (also known as carbohydrates) that have a ubiquitous presence in biology and are a crucial component of the twisted backbone structure of DNA and RNA. As per the existing hypotheses, ammonia (NH3) gave rise to amino acids, while hydrogen cyanide (HCN) led to the formation of nucleobases.
The origin of sugars has been a subject of debate, with some limitations to the theory that the first sugars emerged from formaldehyde (CH2O) reactions. Nonetheless, several researchers support this notion.
“The formaldehyde reactions proposed by this theory are quite messy—they have uncontrolled side reactions and other drawbacks due to formaldehyde’s high reactivity under the envisioned early-Earth conditions,” adds co-author Charles Liotta.
They have put forward an alternative solution called the “glyoxylose reaction” as a substitute for formaldehyde-based reactions. In this process, glyoxylate initially reacts with itself, generating a chemical called glycolaldehyde that is similar to formaldehyde. According to the experts, this chemical, along with its byproducts and other uncomplicated compounds, could have undergone further reactions, leading to the formation of basic sugars and other products. This method doesn’t have the disadvantages associated with formaldehyde-based reactions.
According to origin-of-life chemistry theories, glyoxylate plays a significant role. In 2007, Albert Eschenmoser, a Swiss chemist, proposed that it might have served as the precursor for several original biomolecules. Recently, in a 2020 Nature Chemistry publication, Greg Springsteen, PhD, a chemist from Furman University, also suggested that glyoxylate could have facilitated the initiation of a rudimentary form of the tricarboxylic acid (TCA) cycle, a fundamental metabolic process present in almost all life forms on our planet.
Krishnamurthy and his colleagues are presently engaged in laboratory experiments to establish that the glyoxylose reaction could have plausibly produced the initial sugars.
“Such a demonstration would expand the role of glyoxylate as a versatile molecule in prebiotic chemistry and further stimulate the search for its own origin on the prebiotic Earth,” Krishnamurthy adds.
In addition, the researchers are exploring possible industrial applications of glyoxylate-forming reactions, which have the ability to consume carbon dioxide and may be utilized to decrease CO2 levels either within industrial settings or on a global scale to mitigate the effects of climate change.
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