The discussion revolves around the discovery of a protein series termed "Hemolithin" by a Harvard team, purportedly found in an asteroid. Participants explore the implications of this finding for astrobiology, the nature of the molecules involved, and their potential origins, including abiotic processes. The conversation touches on definitions of proteins versus peptides and the broader implications for the understanding of life's origins.
Participants generally express disagreement on the classification of Hemolithin and its implications for biological processes. There is no consensus on whether these molecules should be considered proteins or peptides, and the discussion remains unresolved regarding their origins and significance.
Participants highlight the need for caution in interpreting the findings, particularly regarding the biological implications of the term "protein" and the potential for artifacts in the research. The discussion also reflects uncertainty about the evolutionary context of these short sequences.
Structures are presented in S5 for each of these. 2320 and 2364 have 32 amino acid residues while 2124 has 30. An additional 34 amino acid structure at 2402 is also proposed in S5, to fit two peaks within the 4641Da cluster. The chain lengths in each anti-parallel configuration are therefore 16 residues for 2320 and 2364, 15 residues for 2124 and 17 residues for 2402. As discussed herein the glycine residues are subject to varying degrees of hydroxylation, but the more constant parameter is the number of glycines per side. We propose calling the 16-residue entity Hemolithin 16, and the 15 or 17-residue entities Hemolithins 15 or 17.
The "evolution of more complex proteins" suggests a Darwinian selection process. Just to be clear, no one is suggesting that this particular protein, or mini-protein, or polypeptide was the result of DNA, RNA, or any other kind of replication process. So it's potential to "evolve" is really limited.jim mcnamara said:Assuming the hemolithin paper is not the result of an artifact, short sequences like this would reasonably be expected to arise in the course of the evolution of more complex proteins.
jim mcnamara said:@Ygggdrasil
FWIW -
In this thread
https://www.physicsforums.com/threads/science-white-paper-on-miniproteins.979258/
There is a category of short and redundant amino acids sequences called miniproteins that are biologically active.
White paper:
https://www.sciencemag.org/news/2019/10/new-universe-miniproteins-upending-cell-biology-and-genetics
Assuming the hemolithin paper is not the result of an artifact, short sequences like this would reasonably be expected to arise in the course of the evolution of more complex proteins. I am not so sure about the presence of the Lithium atom in the results. The mass fraction of Lithium is way down the list of elements ordered by abundance in the Universe, ditto the Solar System.