June ArXivery

Articles studied June 2022 - some of which might go to Slashdot.

Biological Homochirality

Other things happened.

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June science readings.

Maybe I'll get back to something "productive" now. I think Uncle Roger (deceased) would approve.

Biological Homochirality and the Search for Extraterrestrial Biosignatures

https://arxiv.org/pdf/2205.01193.pdf

Eny Fule Noe that the homochirality of biological molecules is a really important topic in O(s)OL studies. Homochirality is probably essential in biochemistry, because of the concentration problem -if you don't control chirality of reactions, then every chiral centre (which are inevitable in molecules above a fairly low complexity threashold) will approximately halve your reaction efficiency.

Is it important to biochemistry? Ask any thalidomide victim (the sedative is harmless ; flip one chiral centre and you get the teratogen.

Chirality is mentioned in almost every discussion of amino acids and proteins, because amino acids other than glycine (the simplest) has at least one chiral centre. It's also important in sugars, because most sugar monomers have one or two chiral centres, in addition to any introduced in the polytmerisation. Unsurprisingly, chirality is important to getting proteins to fold up into the "right" shape.

This paper examines evidence for homochiral enantiomeric excess (of L- over D, or of D- over L enantiomers) exists beyond Earth, elsewhere in the Solar system, in the "local neighbourhood" (galactic arm, galaxy group - what do they mean?) or in the wider universe.

This short (8 pages) paper seems to be an introduction or a summary for a forthcoming book on the subject, but the publication isn't named.

The big question is, would the detection of a robust homochirality signal by remote (spectroscopic, probably) means be a robust biosignature?

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