In a chance discovery, researchers have for the first time observed the emergence of something akin to metabolism in molecules that also self-replicate. The replicator molecules catalyse a reaction that produces compounds that help to make the replicator’s own building blocks. It might be one of the most lifelike chemical systems ever created, combining two of life’s three essential features – replication, metabolism and compartmentalisation.
‘What it can teach us is that those functions that we see in living systems, they are not unique to life as we know it,’ says origin of life scientist Kamila Muchowska from the University of Strasbourg, France, who wasn’t involved in the work…
Systems that either replicate or perform metabolism-like reactions have existed before, and some can even switch from one function to the other upon addition of chemicals or environmental changes. But a team around Sijbren Otto from the University of Groningen in the Netherlands has now created molecules that do both at the same time.Katrina Krämer, “Self-replicating molecules show signs of metabolism for the first time” at Chemistry World
Paper 1. (paywall)
Paper 2. (paywall)
They use quite a generous definition of “self replicator”. It has nothing to do with replication of biopolymers in life, yet they intend for the work to be encouraging to abiogenesis. Here are a few of the serious limitations for the application of this to abiogenesis:
1) The starting monomers are purified, concentrated, homochiral molecules purchased from a synthetic peptide lab. Certainly not prebiotically plausible.
2) the starting monomers have no relation to any biopolymer known in life – they are short polypeptides connected to a benzene dithiol.
3) the starting monomers do not covalently bond to create a polymer (as in life); they merely afinitize to form a macromolecular structure. Mechanical perturbation breaks the growing macromolecule to allow for an increased number of nucleation sites that subsequently grow. This is called “self-replication”. It is closer to crystal growth than to replication of any biopolymer.
4) The system is not capable of molecular evolution because any “replication errors” that could convey a benefit would not be passed on to “daughter” molecules (i.e., no “information” could be “passed down” from “generation to generation”).
The novelty in this paper is that they found catalytic abilities created by the macromolecular structure that could enhance the growth rate of this macromolecule.
So, it is entirely distinct from life, but intended to demonstrate one principle that is required for abiogenesis.
The fact that it is recognized as a meaningful contribution is a testimony to the desperation to show progress—it stands out only because no meaningful progress can be made in any direction that is actually relevant to life.