N-Carbamoyl Amino Acid
N-carbamoyl amino acids (CAAs) are prebiotically relevant organic compounds bearing both carboxylic (−COOH) and ureido (−NH-CO-NH2) functional groups. They are precursors to amino acids (in which an amino group −NH2 replaces the ureido group) and to hydantoins, the latter being cyclic, dehydrated forms of CAAs. CAAs are products of the Bücherer-Bergs synthesis, hence possible side products of the prebiotic formation of amino acids. Alternately, CAAs are also reversibly formed by spontaneous reaction of urea or cyanic acid with amino acids. CAAs are possible prebiotic precursors of peptides through the formation of N-carboxyanhydrides (NCAs), for example, by nitrosation. Since the ureido group bears chemical energy, the spontaneous hydrolytic decomposition of CAAs is also able to induce NCA formation, which is suggested by the formation of peptides in low yield from CAAs.