Synthesis and characterization of peptides after high-energy impact on the icy matrix: Preliminary step for further UV-induced formation

In the interstellar medium, the most probable source of organic molecules could be non-equilibrium processes driven by photons, cosmic rays, shock waves and solid bodies’ collisions. The dense cold phase of ISM host icy dust grains—important chemical catalyst during its life cycle. Such particles consist of mineral core composed by silicate or olivine admixed with metal sulfides and oxides, with the water-icy envelope containing organic molecules. Organic molecules in the ISM evolve and become later incorporated in solar system material (comets and meteorites).The formation of polypeptides from single amino acids was traced in simulation experiments representing the inner structure of icy dust grains. Experimental chamber was irradiated at subzero temperatures at the dosage of 2.54 kRad/min. Solid frozen solutions of Gly and Phe were taken as the experimental samples inserted into the metal tube kept at subzero temperatures in the presence of liquid nitrogen. Formation of di- and tri-peptides was demonstrated after applying mass-spectrometry and high performance liquid chromatography (HPLC) techniques.Having polypeptides within the icy matrix, dust grains with ice mantles are transported to warm, dense and active protostellar regions, where ultraviolet irradiation may become important and alter the grain composition. Furthermore UVC radiation may contribute to the formation of additional amounts of polypeptides, since short-wave photons are totally adsorbed by a thin outer layer. This presumption coincides with our previous investigations concerning UV impact on prebiotic formation of the main biological molecules. Combination of two irradiation types in different stages of interstellar flight could compensate the effects of low reagents concentration and temperature. Since the primordial Earth had no atmosphere, the natural carriers could get freely onto its surface and thus raise the concentration of organic molecules.