Alien chiral chemistry

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    Alien Biology Chirality
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SUMMARY

The discussion centers on the potential for terrestrial fungi and bacteria to utilize 'Other Hand' enantiomers in alien chiral chemistry. It is established that while terrestrial biology predominantly favors left-handed amino acids, some bacteria possess specialized enzymes, known as racemases, that can utilize nonstandard, including wrong-handed amino acids. The conversation highlights that these nonstandard amino acids can be formed through abiological racemization reactions and may accumulate if not consumed. The implications for alien biology suggest that different chiral preferences could exist, impacting biochemical processes.

PREREQUISITES
  • Understanding of chirality in organic chemistry
  • Knowledge of amino acid structures and classifications
  • Familiarity with bacterial enzyme functions, specifically racemases
  • Basic principles of abiological reactions and racemization
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  • Research the role of racemases in bacterial metabolism
  • Explore the implications of chirality in extraterrestrial biochemistry
  • Investigate the synthesis and utilization of nonstandard amino acids in various organisms
  • Study the effects of abiological processes on amino acid chirality
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Researchers in astrobiology, organic chemists, microbiologists, and anyone interested in the biochemical implications of chirality in extraterrestrial life forms.

Nik_2213
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A lot of terrestrial biology has specific chirality, the 'Other Hand' being bio-unavailable or toxic...
As 'our' set is product of aeons of happenstance and evolution, alien biology probably differs.
( I'm thinking genuinely alien 'alien' rather than eg 'seeding' or panspermia...)
Can terrestrial fungi / bacteria use 'Other Hand' enantiomers as-is, without degrading to simpler ?
 
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I don't see why not. I have read that our chirality is very slightly favored energetically. I've never been sure to believe it or not.
 
Hornbein said:
I don't see why not. I have read that our chirality is very slightly favored energetically. I've never been sure to believe it or not.
"Why" might be "because they don´t produce much of them".
But even if living enzymes did not produce or use wrong handed amino acids, some of them are formed by purely abiological racemization reactions from left handed enantiomers. If nobody at all ate or used them, they would build up.
In fact, several bacteria do use nonstandard, including wrong handed amino acids. They put them in specialized places like antibiotic oligopeptides and cell wall glycopeptides. Nonstandard amino acids including wronghanded ones are refractory in that standard enzymes designed for standard amino acids often fail at them. But some bacteria do have enzymes specialized for nonstandard amino acids... including wrong handed amino acids. One group of enzymes specialized for wrong-handed amino acids is "racemases".
When bacteria meet supplies of wrong handed amino acids, do they just break them down, or use directly for their specialized products (antibiotics, cell wall glycopeptides)?
 
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