24/7 Space News
New study provides novel insights into the cosmic evolution of amino acids
illustration only
New study provides novel insights into the cosmic evolution of amino acids
by Staff Writers
Tsukuba, Japan (SPX) May 26, 2023

All biological amino acids on Earth appear exclusively in their left-handed form, but the reason underlying this observation is elusive. Recently, scientists from Japan uncovered new clues about the cosmic origin of this asymmetry. Based on the optical properties of amino acids found on the Murchison meteorite, they conducted physics-based simulations, revealing that the precursors to the biological amino acids may have determined the amino acid chirality during the early phase of galactic evolution.

If you look at your hands, you will notice that they are mirror images of each other. However, no matter how hard you try to flip and rotate one hand, you will never be able to superimpose it perfectly over the other. Many molecules have a similar property called "chirality," which means that the "left-handed" (L) version of a molecule cannot be superimposed onto its "right-handed" (D) mirror image version. Even though both versions of a chiral molecule, called "enantiomers," have the same chemical formula, the way they interact with other molecules, especially with other chiral molecules, can vary immensely.

Interestingly, one of the many mysteries surrounding the origin of life as we know it has to do with chirality. It turns out that biological amino acids (AAs)-the building blocks of proteins-on Earth appear only in one of their two possible enantiomeric forms, namely the L-form. However, if you synthesize AAs artificially, both L and D forms are produced in equal amounts. This suggests that, at some early point in the past, L-AAs must have come to dominate a hetero-chiral world. This phenomenon is known as "chiral symmetry breaking."

Against this backdrop, a research team led by Assistant Professor Mitsuo Shoji from University of Tsukuba, Japan, conducted a study aimed at solving this mystery. As explained in their paper published in The Journal of Physical Chemistry Letters, the team sought to find evidence supporting the cosmic origin of the homochirality of AAs on Earth, as well as iron out some inconsistencies and contradictions in our previous understanding.

"The idea that homochirality may have originated in space was suggested after AAs were found in the Murchison meteorite that fell in Australia in 1969," explains Dr. Shoji. Curiously enough, in the samples obtained from this meteorite, each of the L-enantiomers was more prevalent than its D-enantiomer counterpart. One popular explanation for this suggests that the asymmetry was induced by ultraviolet circularly polarized light (CPL) in the star-forming regions of our galaxy. Scientists verified that this type of radiation can, indeed, induce asymmetric photochemical reactions that, given enough time, would favor the production of L-AAs over D-AAs. However, the absorption properties of the AA isovaline are opposite to those of the other AAs, meaning that the UV-based explanation alone is either insufficient or incorrect.

Against this backdrop, Dr. Shoji's team pursued an alternate hypothesis. Instead of far-UV radiation, they hypothesized that the chiral asymmetry was, in fact, induced specifically by the CP Lyman-a (Lya) emission line, a spectral line of hydrogen atom that permeated the early Milky Way. Moreover, instead of focusing only on photoreactions in AAs, the researchers investigated the possibility of the chiral asymmetry starting in the precursors to the AAs, namely amino propanals (APs) and amino nitriles (ANs).

Through quantum mechanical calculations, the team analyzed Lya-induced reactions for producing AAs along the chemical pathway adopted in Strecker synthesis. They then noted the ratios of L- to D-enantiomers of AAs, APs, and ANs at each step of the process.

The results showed that L-enantiomers of ANs are preferentially formed under right-handed CP (R-CP) Lya irradiation, with their enantiomeric ratios matching those for the corresponding AAs. "Taken together, our findings suggest that ANs underlie the origin of the homochirality," remarks Dr. Shoji. "More specifically, irradiating AN precursors with R-CP Lya radiation lead to a higher ratio of L-enantiomers. The subsequent predominance of L-AAs is possible via reactions induced by water molecules and heat."

The study thus brings us one step closer to understanding the complex history of our own biochemistry. The team emphasizes that more studies focused on ANs need to be conducted on future samples from asteroids and comets to validate their findings. "Further analyses and theoretical investigations of ANs and other prebiotic molecules related to sugars and nucleobases will provide new insights into the chemical evolution of molecules and, in turn, the origin of life," concludes an optimistic Dr. Shoji.

Be sure to stay tuned as scientists continue to piece together this one grand puzzle called life!

Research Report:Enantiomeric Excesses of Aminonitrile Precursors Determine the Homochirality of Amino Acids

Related Links
University of Tsukuba
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth

Subscribe Free To Our Daily Newsletters

The following news reports may link to other Space Media Network websites.
Researchers uncover how primordial proteins formed on prebiotic earth
Sendai, Japan (SPX) May 15, 2023
How did catalytic organic polymers emerge on prebiotic Earth? Answering this essential question will unlock key understandings in the origin of life. A team of scientists at Tohoku University have recently found a potential environment for the reaction that produced catalytic organic polymers. To do so, they dried down amino acid solutions containing boric acid and found that boric acid catalyzes polypeptide synthesis under neutral and acidic conditions. The longest peptides formed in the experime ... read more

ASPINA Launches Space Team

Solar Foods one of the Phase II winners of NASA Deep Space Food Challenge

Virgin Galactic resumes spaceflights after two year pause

The Huginn mission - an overview

South Korea hails successful launch of homegrown rocket

Stratolaunch expands fleet with Virgin Orbit's modified Boeing 747

NASA, Boeing provide update on Starliner flight test readiness

Rocket Lab launches second batch of TROPICS satellites for NASA

Ingenuity's high-stakes game of hide and seek

Meet the scientist (sort of) spending a year on Mars

Hitting the road after three weeks at Ubajara: Sols 3839-3840

MAHLI works the night shift: Sols 3837-3838

China launches Shenzhou-16 with first civilian to space station

China's 'space dream': A Long March to the Moon and beyond

Chinese mission with first civilian reaches space station

China launches Shenzhou-16 with first civilian to space station

Terran Orbital Announces $37.1 Million Registered Direct Offering

A Saudi Arabian satellite launches on a SpaceX Falcon 9 rocket

NASA funds small business to advance tech for Space, Earth

Iridium adds to constellation resilience with launch of spare satellites

Technicians apply thermal protection material to SLS

What do we know about the mechanics of two-dimensional materials

Understanding boiling to help the nuclear industry and space missions

Arabsat Badr-8 launched

The search for habitable planets expands

Astronomers discover a key planetary system to understand the formation mechanism of the mysterious 'super-Earths'

New study provides novel insights into the cosmic evolution of amino acids

Chemistry: Meteoritic and volcanic particles may have promoted origin of life reactions

Juice deployments complete: final form for Jupiter

First observation of a Polar Cyclone on Uranus

Research 'solves' mystery of Jupiter's stunning colour changes

NASA's Juno mission closing in on Io

Subscribe Free To Our Daily Newsletters

The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.