A pathway to peptides in space through the condensation of atomic carbon

TL;DR

This study demonstrates a novel space chemistry pathway where atomic carbon condenses on cosmic dust to form peptides directly, bypassing amino acids, which could be crucial for life's origins.

Contribution

It provides experimental evidence for peptide formation in space via carbon condensation on dust, a pathway previously unconfirmed.

Findings

Peptides can form in space without water or irradiation.

The process involves common interstellar molecules like CO, C, and NH3.

Peptides of various lengths are produced through polymerization.

Abstract

Organic molecules are widely present in the dense interstellar medium, and many have been synthesized in the laboratory on Earth under the conditions typical for an interstellar environment. Until now, however, only relatively small molecules of biological interest have been demonstrated to form experimentally under typical space conditions. Here we prove experimentally that the condensation of carbon atoms on the surface of cold solid particles (cosmic dust) leads to the formation of isomeric polyglycine monomers (aminoketene molecules). Following encounters between aminoketene molecules, they polymerize to produce peptides of different lengths. The chemistry involves three of the most abundant species (CO, C and NH$_3$) present in star-forming molecular clouds, and proceeds via a novel pathway that skips the stage of amino acid formation in protein synthesis. The process is efficient, even at low temperatures, without irradiation or the presence of water. The delivery of biopolymers formed by this chemistry to rocky planets in the habitable zone might be an important element in the origins of life.