Prebiotic Oligomer Assembly: What Was the Energy Source?

Area of Science:

• Origin of life studies
• Prebiotic chemistry
• Polymerization reactions

Background:

• Polymerization of nucleotides and amino acids is crucial for life's origin.
• Condensation reactions have unfavorable Gibbs energies, yielding small oligomers.
• Geochemical condensing agents have been proposed but are limited by episodic sources and hydrolytic instability.

Purpose of the Study:

• To investigate mechanisms for overcoming unfavorable thermodynamics in prebiotic polymerization.
• To propose a novel mechanism for achieving ascending sequences of complex polymers.

Main Methods:

• Thermodynamic analysis of condensation reactions.
• Evaluation of proposed geochemical activators.
• Theoretical modeling of evaporating pools and wetting-drying cycles.

Main Results:

• Proposed activators provide only modest yields and are limited by instability.
• Oligomer formation is inherently antientropic.
• Evaporating pools with wetting-drying cycles create favorable entropy changes.

Conclusions:

• Evaporating pools overcome thermodynamic barriers by concentrating reactants at air/water interfaces.
• Reduced configurational freedom in evaporating pools drives polymerization exergonically.
• This mechanism enables the production of ascending sequences of complex polymeric products essential for life's origin.