"Rice University chemist James Tour, along with co-authors M. C.
The study found that the decay time constant approximates the decay time constant of a dimer (a pair of amino acids or nucleotides joined by a single bond) divided by the length of the chain.
---In other words, longer chains degrade more quickly, with the time constant decreasing in direct proportion to chain length. They summarize their results as follows:
More specifically, the half-life of a dipeptide — two amino acids linked by a peptide bond, as found in proteins — is approximately 7 years. Therefore, a polypeptide chain of 200 amino acids, which is typical for many functional proteins, has a half-life of only 13 days. The situation is even more severe for RNA. A chain of two nucleotides has a half-life of about 100 days, meaning that an RNA strand of 200 nucleotides would degrade in roughly 12 hours. Both classes of molecules decay far more rapidly than they could plausibly form under natural conditions, making their spontaneous emergence highly unlikely in any undirected origin-of-life scenario.
For a typical protein, the discovery time in one liter of water would be on the order of 10,000 years, which is over 100,000 times longer than most protein half-lives. The situation is even worse for RNA since it has a much shorter half-life. Yet origin scenarios require far larger volumes than a liter. The synthesis of the building blocks of life requires at least eight different environments, so the volume of water that a protein would need to explore to find a nascent cell would be enormous.
"For a polymer of N-monomer-units long, or N-mer, which has a dimer decay time constant of t, the polymer decay time constant is proved to be closely approximated by t/N (under rather general assumptions). The implications of this for abiogenesis are profound, namely that there would be small amounts of time available (order of days) for a prebiotic sequence of a condensation polymer to serve as the primary information-bearing code for the last universal common ancestor."
More specifically, the half-life of a dipeptide — two amino acids linked by a peptide bond, as found in proteins — is approximately 7 years. Therefore, a polypeptide chain of 200 amino acids, which is typical for many functional proteins, has a half-life of only 13 days. The situation is even more severe for RNA. A chain of two nucleotides has a half-life of about 100 days, meaning that an RNA strand of 200 nucleotides would degrade in roughly 12 hours. Both classes of molecules decay far more rapidly than they could plausibly form under natural conditions, making their spontaneous emergence highly unlikely in any undirected origin-of-life scenario.
For a typical protein, the discovery time in one liter of water would be on the order of 10,000 years, which is over 100,000 times longer than most protein half-lives. The situation is even worse for RNA since it has a much shorter half-life. Yet origin scenarios require far larger volumes than a liter. The synthesis of the building blocks of life requires at least eight different environments, so the volume of water that a protein would need to explore to find a nascent cell would be enormous.
The protein could never find its way into a staging ground for life’s origin before degrading."
EN&V
