Limits...
Characterization of RNA-Like Oligomers from Lipid-Assisted Nonenzymatic Synthesis: Implications for Origin of Informational Molecules on Early Earth.

Mungi CV, Rajamani S - Life (Basel) (2015)

Bottom Line: The resultant products were characterized to understand their chemical makeup.Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules.This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

View Article: PubMed Central - PubMed

Affiliation: Indian Institute of Science Education and Research (IISER), Pune, Maharashtra 411008, India. cvmungi@students.iiserpune.ac.in.

ABSTRACT
Prebiotic polymerization had to be a nonenzymatic, chemically driven process. These processes would have been particularly favored in scenarios which push reaction regimes far from equilibrium. Dehydration-rehydration (DH-RH) cycles are one such regime thought to have been prevalent on prebiotic Earth in niches like volcanic geothermal pools. The present study defines the optimum DH-RH reaction conditions for lipid-assisted polymerization of nucleotides. The resultant products were characterized to understand their chemical makeup. Primarily, our study demonstrates that the resultant RNA-like oligomers have abasic sites, which means these oligomers lack information-carrying capability because of losing most of their bases during the reaction process. This results from low pH and high temperature conditions, which, importantly, also allows the formation of sugar-phosphate oligomers when ribose 5'-monophosphates are used as the starting monomers instead. Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules. This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

No MeSH data available.


Related in: MedlinePlus

Graphical representation of HPLC chromatograms obtained from Cyc7 samples of DH-RH reactions of 5'-AMP (5 mM) and POPC (1 mM) carried out using varying dehydration time scales at pH 2. The optimum drying time for these reactions seems to be around 1 h.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4390841&req=5

life-05-00065-f005: Graphical representation of HPLC chromatograms obtained from Cyc7 samples of DH-RH reactions of 5'-AMP (5 mM) and POPC (1 mM) carried out using varying dehydration time scales at pH 2. The optimum drying time for these reactions seems to be around 1 h.

Mentions: To identify this, various dehydration time scales from 30 min to 3 h were analyzed. It was observed that longer dehydration time periods did indeed result in higher yields of oligomers, as shown in Figure 5. However, increasing the dehydration time period to over 2 h resulted only in a marginal increase in yields of higher oligomers. Overall, one to two hours of dehydration was found to be optimum. In addition to the above, a reaction with a drying time of ~12 h was also performed over a total of 60 h. It was expected that such a long drying time might result in much higher breakdown, owing to possible thermal decomposition. Interestingly, the extent of breakdown was not very different in a 1 h dehydration time reaction versus a ~12 h dehydration time reaction, after accounting for the overall time differences. Higher oligomers, which were not resolved by HPLC, seem to have increased over this period, as is indicated by pronounced trailing (Figure S2, supplementary data). This suggests that the reaction is robust even when carried out for prolonged time periods (over days).


Characterization of RNA-Like Oligomers from Lipid-Assisted Nonenzymatic Synthesis: Implications for Origin of Informational Molecules on Early Earth.

Mungi CV, Rajamani S - Life (Basel) (2015)

Graphical representation of HPLC chromatograms obtained from Cyc7 samples of DH-RH reactions of 5'-AMP (5 mM) and POPC (1 mM) carried out using varying dehydration time scales at pH 2. The optimum drying time for these reactions seems to be around 1 h.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390841&req=5

life-05-00065-f005: Graphical representation of HPLC chromatograms obtained from Cyc7 samples of DH-RH reactions of 5'-AMP (5 mM) and POPC (1 mM) carried out using varying dehydration time scales at pH 2. The optimum drying time for these reactions seems to be around 1 h.
Mentions: To identify this, various dehydration time scales from 30 min to 3 h were analyzed. It was observed that longer dehydration time periods did indeed result in higher yields of oligomers, as shown in Figure 5. However, increasing the dehydration time period to over 2 h resulted only in a marginal increase in yields of higher oligomers. Overall, one to two hours of dehydration was found to be optimum. In addition to the above, a reaction with a drying time of ~12 h was also performed over a total of 60 h. It was expected that such a long drying time might result in much higher breakdown, owing to possible thermal decomposition. Interestingly, the extent of breakdown was not very different in a 1 h dehydration time reaction versus a ~12 h dehydration time reaction, after accounting for the overall time differences. Higher oligomers, which were not resolved by HPLC, seem to have increased over this period, as is indicated by pronounced trailing (Figure S2, supplementary data). This suggests that the reaction is robust even when carried out for prolonged time periods (over days).

Bottom Line: The resultant products were characterized to understand their chemical makeup.Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules.This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

View Article: PubMed Central - PubMed

Affiliation: Indian Institute of Science Education and Research (IISER), Pune, Maharashtra 411008, India. cvmungi@students.iiserpune.ac.in.

ABSTRACT
Prebiotic polymerization had to be a nonenzymatic, chemically driven process. These processes would have been particularly favored in scenarios which push reaction regimes far from equilibrium. Dehydration-rehydration (DH-RH) cycles are one such regime thought to have been prevalent on prebiotic Earth in niches like volcanic geothermal pools. The present study defines the optimum DH-RH reaction conditions for lipid-assisted polymerization of nucleotides. The resultant products were characterized to understand their chemical makeup. Primarily, our study demonstrates that the resultant RNA-like oligomers have abasic sites, which means these oligomers lack information-carrying capability because of losing most of their bases during the reaction process. This results from low pH and high temperature conditions, which, importantly, also allows the formation of sugar-phosphate oligomers when ribose 5'-monophosphates are used as the starting monomers instead. Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules. This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

No MeSH data available.


Related in: MedlinePlus