Extended Data Fig. 6: Putative ancient catalysts.
From: Environmental boundary conditions for the origin of life converge to an organo-sulfur metabolism
(a) In extant biochemistry, keto acids are converted to amino acids using transamination or reductive amination reaction mechanisms, which are then polymerized using a phosphate or thioester-coupled mechanism to make polypeptides. (b) If prebiotic environments did not have a source of fixed nitrogen, then keto acids could have been reduced to -hydroxy acids, which could then be polymerized into polyesters either with4 or without55 thioester bond breaking.
