[GADV]-Protein World Hypothesis on the Origin of Life

Abstract

RNA world hypothesis is widely accepted by many researchers at present as an idea for explanation of the emergence of life because it has been considered that acquisition of genetic information or genes must precede the creation of proteins with catalytic functions and that formation process of “chicken and egg relationship” observed between genes and proteins could be explained by the RNA world hypothesis. But the RNA world hypothesis has many weak points, as follows. (1) RNA as well as nucleotides would be not only prebiotically synthesized from simple inorganic compounds but also self-replicated. (2) Even if RNA were self-replicated, it is also quite difficult for the self-replicated RNA to carry genetic information since capability of RNA for self-replication is not relevant to the genetic function or triplet base sequences for protein synthesis. On the other hand, [GADV]-amino acids, which are encoded by GNC codons, could be easily synthesized on the primitive earth as Miller’s discharge experiments suggested. [GADV]-amino acids would be stable for a long time under prebiotic conditions to accumulate enough amounts of the amino acids required to [GADV]-protein synthesis before the first gene was produced. Introduction of new concepts, protein 0th-order structure of [GADV]-amino acids and pseudo-replication of [GADV]-proteins, has led the GADV hypothesis on the origin of life, where [GADV] or GADV means glycine [G], alanine [A], aspartic acid [D], and valine [V].