5:15 PM - 7:15 PM
[MIS08-P04] Amino acid as a molecular hub beyond peptide
Keywords:Origin of Life, Prebiotic chemistry, Amino acid chemistry, protometabolism
Reactivity of molecules is an intrinsic property of chemical compounds. This means that reaction pathways that are identified in laboratory work can be potentially applied under equivalent geological conditions. Therefore, research on discoveries of new reaction pathways in the field of astrobiology has a significant meaning for us to understand the molecular evolution in the universe and explains the observations from space exploration missions.
One class of the most commonly detected molecules from extraterrestrial objects is amino acid with glycine as the most abundant species. On Earth, amino acids could be synthesized through electrical discharge, UV irradiation and hydrothermal reactions, with Fisher-Tropsch-type, formose-type followed by reductive amination mechanisms. Additionally, glycine has been identified frequently on asteroids such as Ryugu and Bennu and many carbonaceous chondrites. As a result, amino acids are considered as a group of available prebiotic molecules for origin of life (OoL).
What make discoveries on amino acid availability important in the universe is its biological activity for forming peptides, which can potentially act as catalysts for further chemical evolution towards OoL and serves as a signature for the possible existence of life. The polymerization of peptides therefore became a main trend in this field to understand how amino acids were transformed with condensation reagents or wet-dry cycles. However, reactivities of amino acids towards other transformation to produce useful prebiotic molecules are relatively less focused.
Here, we report that oxidation of amino acids by geological available minerals generates hydrogen cyanide and useful organic carboxylic acids. Using glycine as a representative amino acid substrate, cyanide production was confirmed by isotopic labeling experiment using UPLC-ESI-MS. Cyanide was identified to be produced from 2-C position of glycine through a C-C bond cleavage pathway. We found that this reaction could take place under wide ranges of pH (2-13) and temperature (6 – 60 ℃). This oxidation reaction was monitored to reach equilibrium within 24 hours and the minimum amount of glycine required for cyanide generation could be decreased to 1 μM with a yield of 47%. Organic acid generation was analyzed by ion-chromatography and 1H-NMR spectroscopy, amino acid oxidation to carboxylic acids by natural mineral were studied for glycine, alanine, aspartic acid and glutamic acid. It was found that intermediates of reductive Kreb’s Cycle (rTCA cycle), including pyruvate, oxaloacetate, keto-glutarate, succinate, fumarate, malate were detected from alanine, aspartate or glutamate. Glyoxylate might have existed during oxidation of glycine but was quickly converted. Formate, acetate, oxalate and malonate were also identified to be present.
These identified reaction pathways represent the potential of amino acids as a molecular hub for providing useful reagents and are expected to deepen current understanding of organic molecule evolution in prebiotic and astrobiology fields.
One class of the most commonly detected molecules from extraterrestrial objects is amino acid with glycine as the most abundant species. On Earth, amino acids could be synthesized through electrical discharge, UV irradiation and hydrothermal reactions, with Fisher-Tropsch-type, formose-type followed by reductive amination mechanisms. Additionally, glycine has been identified frequently on asteroids such as Ryugu and Bennu and many carbonaceous chondrites. As a result, amino acids are considered as a group of available prebiotic molecules for origin of life (OoL).
What make discoveries on amino acid availability important in the universe is its biological activity for forming peptides, which can potentially act as catalysts for further chemical evolution towards OoL and serves as a signature for the possible existence of life. The polymerization of peptides therefore became a main trend in this field to understand how amino acids were transformed with condensation reagents or wet-dry cycles. However, reactivities of amino acids towards other transformation to produce useful prebiotic molecules are relatively less focused.
Here, we report that oxidation of amino acids by geological available minerals generates hydrogen cyanide and useful organic carboxylic acids. Using glycine as a representative amino acid substrate, cyanide production was confirmed by isotopic labeling experiment using UPLC-ESI-MS. Cyanide was identified to be produced from 2-C position of glycine through a C-C bond cleavage pathway. We found that this reaction could take place under wide ranges of pH (2-13) and temperature (6 – 60 ℃). This oxidation reaction was monitored to reach equilibrium within 24 hours and the minimum amount of glycine required for cyanide generation could be decreased to 1 μM with a yield of 47%. Organic acid generation was analyzed by ion-chromatography and 1H-NMR spectroscopy, amino acid oxidation to carboxylic acids by natural mineral were studied for glycine, alanine, aspartic acid and glutamic acid. It was found that intermediates of reductive Kreb’s Cycle (rTCA cycle), including pyruvate, oxaloacetate, keto-glutarate, succinate, fumarate, malate were detected from alanine, aspartate or glutamate. Glyoxylate might have existed during oxidation of glycine but was quickly converted. Formate, acetate, oxalate and malonate were also identified to be present.
These identified reaction pathways represent the potential of amino acids as a molecular hub for providing useful reagents and are expected to deepen current understanding of organic molecule evolution in prebiotic and astrobiology fields.