Until now, experiments demonstrated the possible formation of relatively small prebiotic molecules under typical space conditions. We demonstrated experimentally that condensation of atomic carbon on the surface of cold solid particles (cosmic dust) leads to the formation of monomeric fragments of polyglycine. These fragments polymerize effectively producing polypeptides. The chemistry involves three of the most common species (CO, C, and NH3) present in star-forming molecular clouds. It proceeds via a novel pathway that skips the stage of amino acids formation in protein synthesis and is effective even at low temperatures without irradiation or presence of water. Therefore, the amount of proteins formed in space through this process could be quite substantial. The delivery of proteins to rocky planets in the habitable zone might be an important element for the origin of life.