Can an Imidazole Be Formed from an Alanyl-Seryl-Glycine Tripeptide under Possible Prebiotic Conditions?

Abstract

The five-membered heterocyclic imidazole group, which is an essential component of purines, histidine and many cofactors, has been abiotically synthesized in different model experiments that attempt to simulate the prebiotic environment. The evolutionary significance of imidazoles is highlighted not only by its presence in nucleic acid components and in histidine, but also by experimental reports of its ability to restore the catalytic activity of ribozymes. However, as of today there are no reports of histidine in carbonaceous chondrites, and although the abiotic synthesis of His reported by Shen et al. (1987, 1990a) proceeds via an Amadori rearrangement, like in the biosynthesis of histidine, neither the reactants nor the conditions are truly prebiotic. Based on the autocatalytic biosynthesis of 4-methylidene-imidazole-one (MIO), a cofactor of some members of the amino acid aromatic ammonia-lyases and aminomutases, which occur via the self-condensation of a simple Ala-Ser-Gly motif within the sequence of the enzymes, we propose a possible prebiotic synthesis of an imidazolide.

Comprehensive reduction of amino acid set in a protein suggests the importance of prebiotic amino acids for stable proteins

“…Sutherland and colleagues recently reported abiotic synthesis pathways for precursors to arginine and asparagine (Supplementary Table S2 ) 47 . Prebiotic syntheses of histidine and imidazolide have also been proposed 47 – 50 .…”

Origin of the Reductive Tricarboxylic Acid (rTCA) Cycle-Type CO2 Fixation: A Perspective

“…A conclusion for the abiotic origin of the TPP-mediated pyruvate synthesis must await the time when the aforementioned possibilities are experimentally tested under simulated primordial geo-electrochemical conditions. As a future experimental study, it is of particular importance to examine whether prebiotically producible heterocyclic compounds with structural features resembling TPP [ 19 , 20 , 21 ] can assist the CO 2 fixation in the proposed environment. The pyrimidine and pyrophosphate parts of TPP may be replaced with simpler structures (e.g., –CH 3 ) without deactivation, and imidazolium and perhaps oxazolium rings could serve as electron carriers in a manner similar to the thiazolium one in TPP.…”

“…Remarkably, replacement of heteroatoms in their ring structures with others (e.g., O or N vs. S) does not inactivate, or in some cases even improves, their functional properties [ 16 , 17 , 18 ]. Various heterocyclic compounds with structural features resembling the two have been synthesized under simulated primitive environmental conditions [ 19 , 20 , 21 ]. Therefore, an alternative possibility is that prebiotic analogs of TPP and biotin with simpler structures that are initially formed via inorganic processes, facilitated the primordial carbon fixation that preceded the origin of life, were incorporated into proto-enzymes in the course of functional evolution, and eventually developed into the modern counterparts.…”

Small and Random Peptides: An Unexplored Reservoir of Potentially Functional Primitive Organocatalysts. The Case of Seryl-Histidine

“…It has been noted, however, that once imidazole can be obtained in a prebiotic environment, it should be, in principle, possible to get to histidine through the Strecker synthesis [39]. Prebiotic imidazole syntheses have been reported in several conditions [40,41,42]. Based on the premise of the Strecker process through an imidazole intermediate, the prebiotic synthesis of histidine has been reported starting from erythrose and formamide [43].…”

“…Based on the premise of the Strecker process through an imidazole intermediate, the prebiotic synthesis of histidine has been reported starting from erythrose and formamide [43]. Some have argued that such a process does not fulfil the criteria that would enable it to be considered prebiotic [42], and therefore, putting into question whether or not this amino acid could in fact be available in early stages of prebiotic evolution remains open for debate.…”