Date:

Metabolism may have started in our early oceans before the origin of life

The chemical reactions behind metabolism – the processes that occur within all living organisms in order to sustain life – may have formed spontaneously in the Earth’s early oceans, according to research published today.

n a study funded by the Wellcome Trust and the European Research Council researchers at the University of Cambridge reconstructed the chemical make-up of the Earth’s earliest ocean in the laboratory. The team found the spontaneous occurrence of reaction sequences which in modern organisms enable the formation of molecules essential for the synthesis of metabolites. These organic molecules, such as amino acids, nucleic acids and lipids, are critical for the cellular metabolism seen in all living organisms

- Advertisement -

The detection of one of the metabolites, ribose 5-phosphate, in the reaction mixtures is particularly noteworthy, as RNA precursors like this could in theory give rise to RNA molecules that encode information, catalyze chemical reactions and replicate.

It was previously assumed that the complex metabolic reaction sequences, known as metabolic pathways, which occur in modern cells, were only possible due to the presence of enzymes. Enzymes are highly complex molecular machines that are thought to have come into existence during the evolution of modern organisms. However, the team’s reconstruction reveals that metabolism-like reactions could have occurred naturally in our early oceans, before the first organisms evolved.

Life on Earth began during the Archean geological eon almost 4 billion years ago in iron-rich oceans that dominated the surface of the planet. This was an oxygen-free world, pre-dating photosynthesis, when the redox state of iron was different and much more soluble to act as potential catalysts. In these oceans, iron, other metals and phosphate facilitated a series of reactions which resemble the core of cellular metabolism occurring in the absence of enzymes.

The findings suggest that metabolism predates the origin of life and evolved through the chemical conditions that prevailed in the worlds earliest oceans.

- Advertisement -

“Our results show that reaction sequences that resemble two essential reaction cascades of metabolism, glycolysis and the pentose-phosphate pathways, could have occurred spontaneously in the earth’s ancient oceans,” says Dr Markus Ralser from the Department of Biochemistry at the University of Cambridge and the National Institute for Medical Research, who led the study.

“In our reconstructed version of the ancient Archean ocean, these metabolic reactions were particularly sensitive to the presence of ferrous iron which was abundant in the early oceans, and accelerated many of the chemical reactions that we observe. We were surprised by how specific these reactions were,” he added.

The conditions of the Archean ocean were reconstructed based on the composition of various early sediments described in the scientific literature which identify soluble forms of iron as one of the most frequent molecules present in these oceans.

Alexandra Turchyn from the Department of Earth Sciences at the University of Cambridge, one of the co-authors of the study said: “We are quite certain that the earliest oceans contained no oxygen, and so any iron present would have been soluble in these oxygen-devoid oceans. It’s therefore possible that concentrations of iron could have been quite high”.

The different metabolites were incubated at temperatures of 50-90˚C, similar to what might be expected close to the hydrothermal vents of an oceanic volcano. These temperatures would not support the activity of conventional protein enzymes. The chemical products were separated and analyzed by liquid chromatography tandem mass spectrometry.

Some of the observed reactions could also take place in water but were accelerated by the presence of metals that served as catalysts. “In the presence of iron and other compounds found in the oceanic sediments, we observed 29 metabolism-like chemical reactions, including those that produce some of the essential chemicals of metabolism, for example precursors to the building blocks of proteins or RNA,” says Dr Ralser.

“These results indicate that the basic architecture of the modern metabolic network could have originated from the chemical and physical constraints that existed on Earth billions of years ago.”

Header Image : WikiPedia CC

Contributing Source : Cambridge University

- Advertisement -
spot_img
Mark Milligan
Mark Milligan
Mark Milligan is multi-award-winning journalist and the Managing Editor at HeritageDaily. His background is in archaeology and computer science, having written over 7,500 articles across several online publications. Mark is a member of the Association of British Science Writers (ABSW), the World Federation of Science Journalists, and in 2023 was the recipient of the British Citizen Award for Education, the BCA Medal of Honour, and the UK Prime Minister's Points of Light Award.
spot_img

Mobile Application

spot_img

Related Articles

Explorers find lost plane of WWII fighter ace

A team of explorers from Pacific Wrecks have discovered the lost plane of WWII ace pilot, Richard Bong.

Rediscovered : Lost reliquary of Stavanger’s patron saint

Archaeologists have rediscovered the remains of the reliquary of St Swithun in a crypt beneath Stavanger Cathedral.

Stone box containing rare ceremonial offerings discovered at Tlatelolco

Archaeologists from the National Institute of Anthropology and History (INAH) have discovered a stone box containing ceremonial offerings during excavations of Temple "I", also known as the Great Basement, at the Tlatelolco archaeological zone.

Excavation uncovers traces of the first bishop’s palace at Merseburg Cathedral Hill

Archaeologists from the State Office for Monument Preservation and Archaeology (LDA) Saxony-Anhalt have uncovered traces of the first bishop’s palace at the southern end of the Merseburg Cathedral Hill in Merseburg, Germany.

BU archaeologists uncover Iron Age victim of human sacrifice

Archaeologists from Bournemouth University have uncovered an Iron Age victim of human sacrifice in Dorset, England.

Archaeologists find ancient papyri with correspondence made by Roman centurions

Archaeologists from the University of Wrocław have uncovered ancient papyri that contains the correspondence of Roman centurions who were stationed in Egypt.

Study indicates that Firth promontory could be an ancient crannog

A study by students from the University of the Highlands and Islands has revealed that a promontory in the Loch of Wasdale in Firth, Orkney, could be the remains of an ancient crannog.

Archaeologists identify the original sarcophagus of Ramesses II

Archaeologists from Sorbonne University have identified the original sarcophagus of Ramesses II, otherwise known as Ramesses the Great.