A Mechanism for the Prebiotic Emergence of Proteins
The first living organisms were not necessarily the result of the assembly of fully structured biochemical mechanisms involving macromolecules, but at least some life-related processes, as we know them today, probably appeared alongside the structural integration and early evolution of these proto-organisms. Along these ideas, we consider that spatial compartmentalization and protein functionality are tightly related in their origin. A possible scenario of this relationship is the early polymerization of amino acids (AA) embedded in amphiphilic membranes. The resulting membrane-embedded proto-proteins could have played an important role modulating the transport of elements or ions between the internal compartment and the environment. This scenario is congruent with selectivity arguments of AA (Hitz & DeLuisi, 2000) (i.e., 20 out of nearly 70 originally available (Croning & Chang, 1993; Engel & Nagy, 1982)) and their homochirality (Hitz et al., 2001). Other mechanisms of peptide bond formation, such as alumina-catalyzed reactions (Bujdak & Rode, 2002), polymerization on clay surfaces (Bujdak & Rode, 1996) and polymerization mediated by thioesters (De Duve, 1996), can also lead to this scenario.
KeywordsPeptide Bond Formation Internal Compartment Polyamino Acid Murchison Meteorite Spatial Compartmentalization
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