24/7 Space News
Shedding light on the synthesis of sugars before the origin of life
(a) Proposed protometabolic pentose pathway leading to the accumulation of aldonates followed by nonselective oxidation to uronates, carbonyl migration, and ss-decarboxylation. (b) First few steps of the pentose phosphate pathway shown for comparison. Reproduced from Yi et al. 2023 JACS Au.
Shedding light on the synthesis of sugars before the origin of life
by Staff Writers
Tokyo, Japan (SPX) Dec 04, 2023

Pentoses are essential carbohydrates in the metabolism of modern lifeforms, but their availability during early Earth is unclear since these molecules are unstable. A new study led by the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology, Japan, reveals a chemical pathway compatible with early Earth conditions and by which C6 aldonates could have acted as a source of pentoses without the need for enzymes. Their findings provide clues about primitive biochemistry and bring us closer to understanding the Origins of Life.

The emergence of life on Earth from simple chemicals is one of the most exciting yet challenging topics in biochemistry and perhaps all of science. Modern lifeforms can transform nutrients into all sorts of compounds through complex chemical networks; what's more, they can catalyze very specific transformations using enzymes, achieving a very fine control over what molecules are produced. However, enzymes did not exist before life emerged and became more sophisticated. Thus, it is likely that various nonenzymatic chemical networks existed at an earlier point in Earth's history, which could convert environmental nutrients into compounds that supported primitive cell-like functions.

The synthesis of pentoses is a prominent example of the above scenario. These simple sugars, containing only five carbon atoms, are the fundamental building blocks of RNA and other molecules that are essential to life as we know it. Scientists have proposed and studied various ways pentoses could have been generated prior to the origin of life, but current theories beg the question: how could pentoses ever accumulate in quantities enough to partake in pre-life reactions if these compounds are extremely short-lived?

To tackle this question, a research team led by Research Scientist Ruiqin Yi from ELSI recently conducted a study to find an alternative explanation for the origin and sustained supply of pentoses on early Earth. They explored an enzyme-free chemical network in which C6 aldonates, which are stable six-carbon carbohydrates, accumulate from various prebiotic sugar sources and then convert back to pentoses.

The proposed chemical pathway begins with gluconate, a stable C6 aldonate that may have been readily available on early Earth through known prebiotic transformations of basic sugars. The next step is the nonselective oxidation of C6 aldonate into uronate; here, the term 'nonselective' means that the oxidation process does not discriminate between the various carbon atoms in the aldonate structure, leaving five possible oxidation outcomes.

Through experiments and theoretical analyses, the researchers delved deep into the various oxidation products to figure out the details of the reaction network. Interestingly, they found that no matter where the oxidation takes place, the resulting uronate compounds can always undergo an intramolecular transformation known as 'carbonyl migration' until the specific compound 3-oxo-uronate is formed. Once this state is reached, 3-oxo-uronate gets easily transformed into pentose through ss-decarboxylation in the presence of H2O2 and a ferrous catalyst, both of which are compatible with the conditions of early Earth.

After establishing and testing the entirety of this complex reaction network, the researchers noticed an important resemblance with a modern biochemical pathway. "We demonstrated a nonenzymatic synthetic pathway for five-carbon sugars that relies on chemical transformations reminiscent of the first steps of the pentose phosphate pathway, a core pathway of metabolism," highlights the lead author Ruiqin Yi. "These results prove that prebiotic sugar synthesis may have overlaps with extant biochemical pathways." Given that sugars are ubiquitous in modern metabolism, the proposed reaction network could have been important for the emergence of the first life-like systems.

The findings of this study are important in the context of astrochemistry and astrobiology. Aldonates were found abundantly in the Murchison meteorite, a famous carbonaceous meteorite that fell to Earth in 1969. In contrast, the canonical carbohydrates found in modern biological systems were absent in it. This implies that aldonates can form and accumulate in extraterrestrial conditions, and the present study suggests that they could play an important role in the origin of the building blocks of life. "We hope this work will shape the next wave of astrobiology to focus on aldonate studies," adds Yi.

In future studies, the research team will focus on whether C6 aldonates could have accumulated enough in early Earth to act as 'nutrients' for the emergence of proto-metabolism. Lead researcher Ruiqin Yi concludes: "We want to understand more how these aldonates can be generated from classic prebiotic sugar reactions, such as the formose reaction and Kiliani-Fischer homologation." Notably, these classic prebiotic sugar reactions are not found in modern metabolism, and thus, the proposed nonenzymatic pathway could act as a much-needed bridge between early sugars and the carbohydrates theoretically used by the first lifeforms.

Research Report:Carbonyl Migration in Uronates Affords a Potential Prebiotic Pathway for Pentose Production

Related Links
Tokyo Institute of Technology
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth

Subscribe Free To Our Daily Newsletters

The following news reports may link to other Space Media Network websites.
Interstellar ice may hold the key to understanding life's origins
Los Angeles CA (SPX) Dec 01, 2023
Recent research, as detailed in a study published in ACS Central Science, presents a novel perspective on the origins of life's essential components, particularly amino acids. The study posits that carbamic acid, a simple amino acid, may have formed in the vicinity of stars or planets within interstellar ices. This groundbreaking hypothesis provides a new avenue for understanding how the building blocks of life might have originated in the universe, far predating life on Earth. Traditionally, it w ... read more

NASA Stennis Achieves Major Milestone for In-Flight Software Mission

Was going to space a good idea

Lost tomato found aboard International Space Station after eight months

Chandrayaan-3 Propulsion Module Successfully Transitions from Lunar to Earth Orbit

Professionals Satellite YPSat Ready for Electromagnetic Compatibility Testing

KAIST Partners with Rocket Lab for NeonSat-1 Launch

NASA identifies probable reason for OSIRIS-REx capsule parachute deployment issue

An incredible pace of SpaceX launch cadence continues with the launch of a Falcon 9 rocket

Mapping Mars: Deep Learning Could Help Identify Jezero Crater Landing Site

How Rocks Say Don't Touch: Sols 4032-4034

Should I Stay or Should I Go Now: Sols 4028-4029

On The Road Again: Sols 4030-4031

CAS Space expands into Guangdong with new rocket engine testing complex

China's Lunar Samples on Display in Macao to Inspire Future Explorers

China Manned Space Agency Delegation Highlights SARs' Role in Space Program

Wenchang Set to Become China's Premier Commercial Space Launch Hub by Next Year

Iridium's New GMDSS Academy to Bolster Safety Training for Maritime Professionals

Embry-Riddle's Innovative Mission Control Lab prepares students for booming space sector

Ovzon and SSC close to sealing satellite communication contract worth $10M

A major boost for space skills and research in North East England

Rogue Space Systems lands inaugural on-orbit service contract

NASA Laser Reflecting Instruments to Help Pinpoint Earth Measurements

Magnetization by laser pulse

CityU develops universal metasurface antenna, advancing 6G communications

Ariel moves from drawing board to construction phase

Digging Deeper to Find Life on Ocean Worlds

Researchers Develop Advanced Algorithm Pandora for Exomoon Hunt

Shedding light on the synthesis of sugars before the origin of life

Unwrapping Uranus and its icy moon secrets

Juice burns hard towards first-ever Earth-Moon flyby

Fall into an ice giant's atmosphere

Juno finds Jupiter's winds penetrate in cylindrical layers

Subscribe Free To Our Daily Newsletters


The content herein, unless otherwise known to be public domain, are Copyright 1995-2023 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.