Meteoritenanalysen ergeben: Aminosäuren entstehen auch bei hohen Temperaturen

[karmaka]

Meteoritenanalysen ergeben: Aminosäuren entstehen auch bei hohen Temperaturen

http://www.nasa.gov/topics/solarsystem/features/life-components.html

In the study, scientists with the Astrobiology Analytical Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md., analyzed samples from fourteen carbon-rich meteorites with minerals that indicated they had experienced high temperatures – in some cases, over 2,000 degrees Fahrenheit. They found amino acids, which are the building blocks of proteins, used by life to speed up chemical reactions and build structures like hair, skin, and nails. [...]

The team also wants to expand their search for amino acids to all known groups of carbon-rich meteorites. There are eight different groups of carbon-rich meteorites, called "carbonaceous chondrites." The new work adds two additional groups to the three previously known to have produced amino acids, leaving three groups to be tested. These three remaining groups have a high metal content as well as evidence for high temperatures. "We'll see if they have amino acids also, and hopefully gain some insight into how they were made," says Burton. When the team began looking for amino acids in carbon-rich meteorites, it was considered somewhat of a long shot, but now: "We would be surprised if we didn't discover amino acids in a carbon-rich meteorite," says Burton.

automatisierte Übersetzung:

http://translate.google.de/translate?hl=de&sl=en&tl=de&u=http%3A%2F%2Fwww.nasa.gov%2Ftopics%2Fsolarsystem%2Ffeatures%2Flife-components.html

Leider fehlen Hinweise auf die genauen Meteoritentypen, die untersucht wurden.

Martin

[karmaka]

Nachgereicht hier jetzt das paper:

A propensity for n-ω-amino acids in thermally altered Antarctic meteorites

    Aaron S. BURTON, Jamie E. ELSILA, Michael P. CALLAHAN, Mildred G. MARTIN,
    Daniel P. GLAVIN, Natasha M. JOHNSON, Jason P. DWORKIN

http://onlinelibrary.wiley.com/doi/10.1111/j.1945-5100.2012.01341.x/abstract

Asteroids and their fragments have impacted the Earth for the last 4.5 Gyr. Carbonaceous meteorites are known to contain a wealth of indigenous organic molecules, including amino acids, which suggests that these meteorites could have been an important source of prebiotic organic material during the origins of life on Earth and possibly elsewhere. We report the detection of extraterrestrial amino acids in thermally altered type 3 CV and CO carbonaceous chondrites and ureilites recovered from Antarctica. The amino acid concentrations of the thirteen Antarctic meteorites ranged from 300 to 3200 parts-per-billion (ppb), generally much less abundant than in amino acid-rich CI, CM, and CR carbonaceous chondrites that experienced much lower temperature aqueous alteration on their parent bodies. In contrast to low-temperature aqueously altered meteorites that show complete structural diversity in amino acids formed predominantly by Strecker–cyanohydrin synthesis, the thermally altered meteorites studied here are dominated by small, straight-chain, amine terminal (n-ω-amino) amino acids that are not consistent with Strecker formation. The carbon isotopic ratios of two extraterrestrial n-ω-amino acids measured in one of the CV chondrites (δ13C approximately −25‰) are consistent with 13C-depletions observed previously in hydrocarbons produced by Fischer-Tropsch type reactions. The predominance of n-ω-amino acid isomers in thermally altered meteorites hints at cosmochemical mechanisms for the preferential formation and preservation of a small subset of the possible amino acids.

http://astrochem.wordpress.com/2012/03/10/nasa-meteorites-reveal-another-way-to-make-lifes-components/

 

Martin

[karmaka]

Neues zur Entstehung von Aminosäuren im All

Discoveries Suggest Icy Cosmic Start for Amino Acids and DNA Ingredients

http://www.nrao.edu/pr/2013/newchem/

[karmaka]

Amorphes kosmisches Eis und Aminosäuren
im Cosmic Ice Lab

Interessant!

http://www.nasa.gov/topics/universe/features/cosmic-ice.html

Amorphous ice is exactly the opposite of the typical ice on Earth, which forms perfect crystals like those that make up snowflakes or frost needles. These crystals are so orderly and predictable that this ice is considered a mineral, complete with a rating of 2.5 on the Mohs scale of hardness—the same rating as a fingernail.

Though almost unheard of on Earth, amorphous ice is so widespread in interstellar space that it could be the most common form of water in the universe. Left over from the age when the solar system was born, it is scattered across vast distances, often as particles no bigger than grains of dust. It's also been spotted in comets and icy moons. [...]

"We find that some amino acids could survive tens to hundreds of millions of years in ice near the surface of Pluto or Mars and buried at least a centimeter [less than half an inch] deep in places like the comets of the outer solar system," says Gerakines. "For a place that gets heavy radiation, like Europa, they would need to be buried a few feet." (These findings were reported in the journal Icarus in August 2012.)

"The good news for exploration missions," says Hudson, "is it looks as if these amino acids are actually more stable than anybody realized at temperatures typical of places like Pluto, Europa and even Mars."

[JFJ]

Hallo,

die beschriebenen n-ω-Aminosäuren (N-Aryloxycarbonyl-ω-Aminocarbonsäuren) sind sehr reaktionsfreudig und kristallisieren schnell aus, weshalb sie den Eintritt in die Atmosphäre in ihrer Struktur überstanden haben. Es sind sog. Monomere.
Bei Temperaturen über 200°C bilden sie Phenol (eine Karbolsäure), welche chemisch gesehen ein Benzolderivat darstellt, welches auch als Leuchtgas aus Lagern von Steinkohleteer auftritt. Diese Aminosäure zählt zu den Alaninen, welche durch die genannte chemische Reaktion aus Acetaldehyd entstehen können. Acetaldehyd kann biogen aus der Zersetzung von organischer Masse entstehen (s. Kohle), oder aber auch als ganz einfache Reaktion der sehr verbindungsfreudigen Elemente Wasserstoff mit Kohlenstoff (Es können sich zwar Polyamide bilden, jedoch nie komplexere Polypeptide). Wobei Kohlenstoff nicht zwangsläufig als organische Verbildung vorliegen muss. Acetaldehyd ist im Prinzip eine Oxidationsform von Ethan, bzw. ein Aldehyd des Ethan.
Der Fund von den genannten Aminosäuren impliziert zwar „Leben vom anderen Stern“, ist wahrscheinlich nur das Ergebnis einer chemischen, zufälligen Reaktion, ohne dass sich auf diese Aminosäuren weiteres Leben aufbauen kann. Eine Bildung bei hohen Temperaturen scheint fraglich, da Aminosäuren bereits ab 200°C denaturieren, Proteine schon viel eher. Ihre Entstehung könnte auf Ethan-reichen Planten stattgefunden haben (Jupiter, Saturn, Neptun). Auch vom Pluto ist Ethaneis bekannt. Denkbar sind alle Umgebungsbedingungen, welche reich an Kohlenstoff und Wasserstoff waren.
Der Bildung zugrunde, muss nicht unbedingt organische Masse liegen.
Andererseits ist Ethan ein gesättigter Kohlenwasserstoff, bei welchem ein Wasserstoffatom ersetzt wurde (= Ethanol). Vielleicht ist einem Außerirdischen ja einfach nur die Destille um die Ohren geflogen 

  Jörg

[karmaka]

Vielen Dank für die Erläuterungen, Jörg!  

Genau, die Destille war's.... 

Hier noch etwas Aktuelles von heute:

LINK

Original

ON THE FORMATION OF DIPEPTIDES IN INTERSTELLAR MODEL ICES
http://iopscience.iop.org/0004-637X/765/2/111/

The hypothesis of an exogenous origin and delivery of biologically important molecules to early Earth presents an alternative route to their terrestrial in situ formation. Dipeptides like Gly-Gly detected in the Murchison meteorite are considered as key molecules in prebiotic chemistry because biofunctional dipeptides present the vital link in the evolutionary transition from prebiotic amino acids to early proteins. However, the processes that could lead to the exogenous abiotic synthesis of dipeptides are unknown. Here, we report the identification of two proteinogenic dipeptides—Gly-Gly and Leu-Ala—formed via electron-irradiation of interstellar model ices followed by annealing the irradiated samples to 300 K. Our results indicate that the radiation-induced, non-enzymatic formation of proteinogenic dipeptides in interstellar ice analogs is facile. Once synthesized and incorporated into the ''building material'' of solar systems, biomolecules at least as complex as dipeptides could have been delivered to habitable planets such as early Earth by meteorites and comets, thus seeding the beginning of life as we know it.