Physics

Meteorite

Murchison meteorite

Nanotechnology

Abiogenesis

Interstellar medium

Membrane

Biomolecule

Galaxy

Astronomy

Protocell

Chondrite

Homochirality

Astrochemistry

Chemistry

Materials science

Early Earth

Dipeptide

Molecule

Solar System

Quantum mechanics

Amino acid

Biochemistry

Astrobiology

Extraterrestrial life

The Astrophysical Journal

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.

ON THE FORMATION OF DIPEPTIDES IN INTERSTELLAR MODEL ICES