Lazcano A, Miller S L
Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-407, Cd. Universitaria, 04510 México D.F., Mexico.
J Mol Evol. 1999 Oct;49(4):424-31.
The heterotrophic theory of the origin of life is the only proposal available with experimental support. This comes from the ease of prebiotic synthesis under strongly reducing conditions. The prebiotic synthesis of organic compounds by reduction of CO(2) to monomers used by the first organisms would also be considered an heterotrophic origin. Autotrophy means that the first organisms biosynthesized their cell constituents as well as assembling them. Prebiotic synthetic pathways are all different from the biosynthetic pathways of the last common ancestor (LCA). The steps leading to the origin of the metabolic pathways are closer to prebiotic chemistry than to those in the LCA. There may have been different biosynthetic routes between the prebiotic and the LCAs that played an early role in metabolism but have disappeared from extant organisms. The semienzymatic theory of the origin of metabolism proposed here is similar to the Horowitz hypothesis but includes the use of compounds leaking from preexisting pathways as well as prebiotic compounds from the environment.
生命起源的异养理论是唯一有实验支持的观点。这源于在强还原条件下益生元合成的简易性。通过将二氧化碳还原为最早生物体所使用的单体来进行有机化合物的益生元合成，也会被视为一种异养起源。自养意味着最早的生物体既能生物合成其细胞成分，又能将它们组装起来。益生元合成途径与最后共同祖先（LCA）的生物合成途径完全不同。导致代谢途径起源的步骤更接近益生元化学，而非LCA中的步骤。在益生元和LCA之间可能存在不同的生物合成途径，这些途径在代谢中起了早期作用，但已从现存生物体中消失。这里提出的代谢起源的半酶理论与霍洛维茨假说相似，但包括利用从现有途径泄漏的化合物以及来自环境的益生元化合物。
