One-step formation of oligopeptide-like molecules from Glu and Asp in hydrothermal environments

Abstract

Biopolymer accumulation in the absence of enzymes is an essential step for the chemical evolution of primitive life-like systems, and successful simulation experiments of prebiotic biopolymer formation have suggested that oligopeptides could have formed near submarine hydrothermal vent environments on primitive earth. However, the yield and length of oligopeptides -- typically limited to 6-mers -- seems to be inadequate. One reason is the rapid formation of diketopiperazines (DKPs) from dipeptides. In this study, using a hydrothermal microflow reactor, we show that the one-step synthesis of oligopeptide-like molecules of length up to 20-mers proceeds from Glu and Asp. Yields of up to 0.17-0.57% were obtained in an acidic solution within 183 s at 250-310 degrees C, as evaluated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis and different types of high-performance liquid chromatography (HPLC) analyses. The present study indicates that Glu and Asp may have played important roles in the chemical evolution of oligopeptide-like molecules in hydrothermal vent environments on primitive earth.

The Organic Composition of Carbonaceous Meteorites: The Evolutionary Story Ahead of Biochemistry

“…Occasionally, these experimental studies also obtain small concentrations of tripeptides and longer oligomers (Imai et al 1999a;Tsukahara et al 2002), but the formation of cyclic dipeptides, which is thermodynamically favored (Shock 1992b), often dominates. It has also been shown that if experiments are started with somewhat larger oligomers, say three or four amino acids in length, then the peptides can be lengthened by hydrothermal reactions involving the monomers (Kawamura et al 2005), and that polymers containing up to 20 amino acids can be generated hydrothermally from glutamic acid or aspartic acid, which do not form cyclic dipeptides (Kawamura and Shimahashi 2008). In addition, hydrothermal dehydration reactions involving alkanoic acids and glycerol produce lipid-like molecules capable of self-assembly (Simoneit et al 2007).…”

Stability of ribonuclease A under hydrothermal conditions in relation to the origin-of-life hypothesis: verification with the hydrothermal micro-flow reactor system

“…Size-exclusion chromatography (SEC) was carried out at a wavelength of 220 nm with an SEC column (TSK-GEL G2000SWXL (/, 7.8 9 300 mm); Tosoh Co. Japan); an eluent containing 0.05 M NaH 2 PO 4 , and 0.3 M NaCl (at pH 7) at a flow rate of 1.0 mL min -1 were used. Matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS) analysis was performed by using a Shimadzu KOMPACT MALDI2 mass spectrometer with a matrix solution containing 10 mg mL -1 2,5-dihydroxybenzoic acid (DHBA) solution (0.1% trifluoroacetic acid (TFA) and 50% ethanol) [21].…”

“…This hypothesis is supported by phylogenetic analysis of existing thermophilic organisms [14][15][16] and experiments conducted by simulation of conditions in the submarine vent systems on primitive Earth [17][18][19][20][21]. Since the hydrothermal origin-of-life hypothesis is still disputed [22][23][24], it needs to be experimentally verified.…”

Development of Micro-Flow Hydrothermal Monitoring Systems and Their Applications to the Origin of Life Study on Earth

“…12). Furthermore, a reduction of the DKP formation was elucidated by the discovery of a one-step oligopeptide formation of up to 20 amino acid units from Glu and Asp mixtures within 180 s at 250 -310 C. 53 The stability of ribonuclease A (RNase A) was studied by the present hydrothermal reactor system, combined using liquid chromatography and enzyme kinetic analysis. 54 This study showed that the activity of RNase A partially remained at temperatures at 200 C within 25 s, where the RNase A is divided into 2 large parts of 4000 -7000 dalton, and degraded to much smaller molecules.…”