Raggi Luciana, Bada Jeffrey L, Lazcano Antonio
Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-407, Cd. Universitaria, 04510 Ciudad de México, Mexico.
Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0212, USA.
Phys Chem Chem Phys. 2016 Jul 27;18(30):20028-32. doi: 10.1039/c6cp00793g.
The significance of experiments that claim to simulate the properties of prebiotic small peptides and polypeptides as models of the polymers that may have preceded proteins is critically addressed. As discussed here, most of these experiments are based only on a small number of a larger set of amino acids that may have been present in the prebiotic environment, supported by both experimental simulations and the repertoire of organic compounds reported in carbonaceous chondrites. Model experiments with small peptides may offer some insights into the processes that contributed to generate the chemical environment leading to the emergence of informational oligomers, but not to the origin of proteins. The large body of circumstantial evidence indicating that catalytic RNA played a key role in the origin of protein synthesis during the early stages of cellular evolution implies that the emergence of the genetic code and of protein biosynthesis are no longer synonymous with the origin of life. Hence, reports on the abiotic synthesis of small catalytic peptides under potential prebiotic conditions do not provide information on the origin of triplet encoded protein biosynthesis, but in some cases may serve as models to understand the properties of the earliest proteins.
对那些声称模拟益生元小肽和多肽性质的实验的意义进行了批判性探讨，这些实验将其作为可能先于蛋白质的聚合物模型。如本文所讨论的，大多数此类实验仅基于益生元环境中可能存在的大量氨基酸中的少数几种，这得到了实验模拟以及碳质球粒陨石中报告的有机化合物种类的支持。小肽的模型实验可能会为促成导致信息寡聚物出现的化学环境的过程提供一些见解，但对于蛋白质的起源却并非如此。大量间接证据表明，催化性RNA在细胞进化早期阶段的蛋白质合成起源中起关键作用，这意味着遗传密码和蛋白质生物合成的出现不再等同于生命的起源。因此，关于在潜在益生元条件下非生物合成小催化肽的报道并未提供有关三联体编码蛋白质生物合成起源的信息，但在某些情况下可作为理解最早蛋白质性质的模型。
