Amino acids from ultraviolet irradiation of interstellar ice analogues

Abstract

Amino acids are the essential molecular components of living organisms on Earth, but the proposed mechanisms for their spontaneous generation have been unable to account for their presence in Earth's early history. The delivery of extraterrestrial organic compounds has been proposed as an alternative to generation on Earth, and some amino acids have been found in several meteorites. Here we report the detection of amino acids in the room-temperature residue of an interstellar ice analogue that was ultraviolet-irradiated in a high vacuum at 12 K. We identified 16 amino acids; the chiral ones showed enantiomeric separation. Some of the identified amino acids are also found in meteorites. Our results demonstrate that the spontaneous generation of amino acids in the interstellar medium is possible, supporting the suggestion that prebiotic molecules could have been delivered to the early Earth by cometary dust, meteorites or interplanetary dust particles.

Experimental investigation of aminoacetonitrile formation through the Strecker synthesis in astrophysical-like conditions: reactivity of methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN)

“…Without hydrolysis, meteoritic amino acids are less abundant. These results can be correlated with the analysis of refractory residues obtained after the VUV irradiation and the warming of ice analogs (Bernstein et al 2002;Muñoz-Caro et al 2002). Without hydrolysis, amino acids are not identified, whereas amino acids are present after the residue hydrolysis (Nuevo et al 2008).…”

Special Issue: Abstracts From the 2008 Issol Meeting

“…In this context, experimental simulations in laboratory have shown that a large quantity of amino acids can be formed by simple vacuum ultraviolet (VUV) irradiation of interstellar ice analogs. These abiotic syntheses of amino acids only lead, without asymmetric induction, to the formation of racemic mixtures (Bernstein et al 2002;Muñoz-Caro et al 2002). In meteorites such as Murchison or Murray, amino acids have been detected (Cronin et al 1980).…”

“…The first step is thus to compare these data with astronomical observations in order to identify the importance of photochemical processes in astrophysical environments. After sample heating, radicals and molecules can rearrange to form a residue which includes complex organic molecules such as amino acids, detected after hydrolysis treatment of the samples (Bernstein et al, 2002;Muñoz-Caro et al, 2002;Nuevo et al, 2008). Without this treatment only very few amounts of amino acids are detected (Nuevo et al, 2008).…”

“…Zamaraev, K. I., Romannikov, V. N., Salganik, R. I., Wlassoff, W. A., and Khramtsov, V. V. (1997) The detection of amino acids in organic residues formed by the UV photolysis of ices mimicking interstellar and cometary environments (H 2 O, CO, CO 2 , CH 3 OH, NH 3 , etc.) showed that molecules of prebiotic interest can form easily in space (Bernstein et al 2002;Muñoz Caro et al 2002). This result agrees with the detection of amino acids in meteorites (Engel and Macko 1997;Cronin and Pizzarello 1997) although their distribution appears to be different (Nuevo et al 2008), and the (still debated) detection of glycine in molecular clouds (Kuan et al 2003;Snyder et al 2005), supporting a scenario where the organic molecules required for life are of extraterrestrial (interstellar or proto-planetary) origin, before being delivered by asteroids, comets, micrometeorites and interstellar dust particles on Earth.…”

“…For more than a decade, our team has been carrying out experiments in space, testing the stability of amino acids, their derivatives, and small peptides that are exposed to solar UV either in the free state or mixed with finely ground meteorite material using. Two experiments were performed on board on Soyouz: Biopan I (Barbier, et al 1998) and Biopan II (Barbier, et al 2002), and on the Mir Station Perseus mission (Boillot, et al 2002).…”