How did the first chemical reactions get started at the origin of life and what was their source of energy? Researchers at the Heinrich Heine University Düsseldorf (HHU) have reconstructed the metabolism of the last universal common ancestor, LUCA. They found that almost all chemical steps used by primordial life to piece together the molecular building blocks of cells are energy-releasing reactions. This identified the long-sought source of energy needed to drive these reactions forward, which has been hiding in plain sight. The energy required to synthesize the building blocks of life comes from within metabolism itself, as long as one essential starting compound is included. The secret ingredient that releases the energy from within at life’s origin is the cleanest, greenest, newest and oldest of all energy carriers: Hydrogen gas, H2.
LUCA existed after life originated so reconstructing its metabolism says little to nothing on the energy type that powered the earliest lifeforms. I didn’t read the actual paper but I am guessing it might differ considerably with the pop article.
With regard to the paper, your description is backwards.
They don’t say “LUCA had this metabolism, therefore life started with similar biochemistry”
They say that the synthesis of the universal core of all biochemistry (also present in LUCA) is exergonic under certain Temp. and pH when hydrogen (H2) is present. Thus the universally shared core of metabolism is able emerge via the thermodynamic favorable release of energy from the reactions involving H2, CO2, NH3, H2S, and phosphate without the need of external energy sources like sun light. The same would be true even for LUCA. The required energy conditions are met in hydrothermal vents like lost city.
That may be true, but it stands to reason that if you can get essentially all of the basal reactions of LUCA to proceed favorably in a single environment, then doing so with an even simpler metabolism shouldn’t be a problem.
After reading the entire article I realized this. Initially I read just the brief snippet Frank posted in his OP.
I agree. I just read the entire article so its a lot clearer.
And the fact that this appears to be possible, at least in principle, is an amazing fact all by itself. Mike Russell, Nick Lane, and Bill Martin might really be on to something about the origin of life. But it is somewhat technologically challenging to set up these reaction conditions in the laboratory. It should be possible to test it in practice, and there are people are working on designing and setting up the equipment so they can try to recreate the conditions in the lab basically as we speak. We live in interesting times.
This paper focuses on the energetic requirements and (apparently) when thermodynamics are concerned, the emergence of life seems quite possible, or even very likely, when the right conditions are met. But as you mentioned, setting up the conditions to see the reactions going might still be challenging due to other reasons.
Thermodynamic favorable is one thing, but as Nick Lane mentions in his books, there are reactions that are favorable - yet - they won’t happen due to a kinetic barrier. To overcome it you either have to input energy initially. Like building a fire. You have to first add some heat and after igniting the fuel the heat released from the fire is also enough to ignite more fuel. However, if the required amount of input energy exceeds the amount that you get out of the reaction in the end, then you don’t get a net yield in energy and the reaction doesn’t sustain itself like a fire.
An extreme (not chemical) example of this is nuclear fusion. At current technology (unless I am not up to date) we need to add more energy to initiate fusion than we get out of it. The reason why stars do emit net positive energy is because of the immense pressures that helps to overcome the kinetic barrier (coulomb barrier specifically), thus the cores of the stars - while still very hot - they don’t need to be as hot as the hydrogen inside our fusion reactors.
And for life to emerge, you likely also have to have specific conditions to overcome the (multiple) kinetic barriers. You probably require an environment of a large volume with different pH and temperature gradients and catalysts (like the metal centers found in enzymes). Conditions which, according to people like Lane, Martin and Russell, are also present the alkaline hydrothermal vents in addition to the energetic requirements. But such a geo-chemical system is extremely complex and very difficult to faithfully replicate in a laboratory, although they have tried to simulate the conditions with tiny vessels with some degree of success.
However, although seemingly paradoxical, I also think that the difficulty to overcome the barrier is rather a ‘good sign’ as well for abiogenesis. Think about it. If nuclear fusion was not hindered by the coulomb barrier, then all the hydrogen would readily fuse very quickly and there likely would be no stars. Likewise, if the reactions that life relies on occurred easily, then life would not emerge either.
Yes. They later abandoned that specific setup because it was extremely chaotic and they often couldn’t replicate the results of some experiments, as the topology of the mineral structures that precipitate out were extremely sensitive to initial reactor conditions and therefore different essentially every time, making it next to impossible to understand what made it some times work and some times not.
Last I heard they’re trying to now 3D print specific chimney precipitate structures to find the ones that “work”, in addition to also constructing a different type of reactor vessel.
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