Stories
Slash Boxes
Comments

SoylentNews is people

SoylentNews is powered by your submissions, so send in your scoop. Only 12 submissions in the queue.
posted by hubie on Wednesday November 27, @12:26AM   Printer-friendly
from the why-cant-we-be-ambidextrous? dept.

NASA is reporting on research concerning the chirality of amino acids and how they may have impacted the development of life here on Earth, and perhaps, elsewhere.

From the NASA Article:

The mystery of why life uses molecules with specific orientations has deepened with a NASA-funded discovery that RNA — a key molecule thought to have potentially held the instructions for life before DNA emerged — can favor making the building blocks of proteins in either the left-hand or the right-hand orientation. Resolving this mystery could provide clues to the origin of life. The findings appear in research recently published in Nature Communications.

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes (catalysts that speed up or regulate chemical reactions). Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acid building blocks in a huge variety of arrangements to make millions of different proteins. Some amino acid molecules can be built in two ways, such that mirror-image versions exist, like your hands, and life uses the left-handed variety of these amino acids. Although life based on right-handed amino acids would presumably work fine, the two mirror images are rarely mixed in biology, a characteristic of life called homochirality. It is a mystery to scientists why life chose the left-handed variety over the right-handed one.

DNA (deoxyribonucleic acid) is the molecule that holds the instructions for building and running a living organism. However, DNA is complex and specialized; it "subcontracts" the work of reading the instructions to RNA (ribonucleic acid) molecules and building proteins to ribosome molecules. DNA's specialization and complexity lead scientists to think that something simpler should have preceded it billions of years ago during the early evolution of life. A leading candidate for this is RNA, which can both store genetic information and build proteins. The hypothesis that RNA may have preceded DNA is called the "RNA world" hypothesis.

If the RNA world proposition is correct, then perhaps something about RNA caused it to favor building left-handed proteins over right-handed ones. However, the new work did not support this idea, deepening the mystery of why life went with left-handed proteins.

In the experiment, the researchers simulated what could have been early-Earth conditions of the RNA world. They incubated a solution containing ribozymes and amino acid precursors to see the relative percentages of the right-handed and left-handed amino acid, phenylalanine, that it would help produce.
[...]
"The findings suggest that life's eventual homochirality might not be a result of chemical determinism but could have emerged through later evolutionary pressures," said co-author Alberto Vázquez-Salazar, a UCLA postdoctoral scholar and member of Chen's research group.
[...]
"Understanding the chemical properties of life helps us know what to look for in our search for life across the solar system," said co-author Jason Dworkin, senior scientist for astrobiology at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and director of Goddard's Astrobiology Analytical Laboratory.

Dworkin is the project scientist on NASA's OSIRIS-REx mission, which extracted samples from the asteroid Bennu and delivered them to Earth last year for further study.

"We are analyzing OSIRIS-REx samples for the chirality (handedness) of individual amino acids, and in the future, samples from Mars will also be tested in laboratories for evidence of life including ribozymes and proteins," said Dworkin.

Journal Reference: Kenchel, J., Vázquez-Salazar, A., Wells, R. et al. Prebiotic chiral transfer from self-aminoacylating ribozymes may favor either handedness. Nat Commun 15, 7980 (2024). https://doi.org/10.1038/s41467-024-52362-x


Original Submission

 
This discussion was created by hubie (1068) for logged-in users only. Log in and try again!
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by jman on Friday November 29, @01:15PM

    by jman (6085) Subscriber Badge on Friday November 29, @01:15PM (#1383752) Homepage
    So, life, at least here on Terra, is left handed.

    Wonder if there's a correlation between that and actual left-handedness?

    The ubiquituous "they" say something like ten percent of mammals are southpaws. So, it's been in the genes for awhile.

    Maybe something like two gears, where the next one runs in reverse direction? So this mysterious second gear is responsible for most folks being righties.

    (Of course that analogy breaks down a little because it would imply three gears, not two, to get the handedness going back in the other direction.)
    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2