Prebiotic metabolic cycles

Metabolism sustains life by converting food into building blocks for biomolecules. At its heart this involves both the breaking down and building up of central metabolites, all of which is facilitated by a series of tailored enzymes. A key question in the origins of life is whether these reaction networks could have emerged without the help of biochemistry. In this work, Joseph Moran and colleagues find that a chemical reaction network emerges from pyruvate and glyoxylate, products of CO₂ reduction, in the presence of Fe(II). This network overlaps significantly with the Krebs cycle, a key part of biological metabolism, as well as breaking its constituents back down into CO₂. In the presence of hydroxylamine and metallic iron, the system also produces the amino acids glycine, alanine, aspartic acid and glutamic acid. Taken together, this work suggests how prebiotic metabolic pathways may have arisen from CO₂, a likely constituent of Earth’s primitive atmosphere.