[Thermodynamics of stacking-interactions in polyA and polyC].

Area of Science:

• Polymer thermodynamics
• Biophysical chemistry
• Nucleic acid science

Context:

• Investigating the thermodynamic stability of nucleic acid structures is crucial for understanding their biological functions.
• Single-chain thermodynamics provides fundamental insights into polymer behavior.
• Previous studies have not fully elucidated the stacking interactions in polyA and polyC at a detailed thermodynamic level.

Purpose:

• To determine the thermodynamic parameters (enthalpy, entropy, heat capacity) of stacking-contact breakdown in single polyA and polyC chains.
• To apply the Ising linear model for analyzing microcalorimetry data.
• To measure temperature-dependent partial heat capacities of these polymers for the first time.

Summary:

• Scanning microcalorimetry was employed to study the thermodynamics of stacking-contact breakdown in polyA and polyC single chains.
• Partial heat capacities were measured between 5-130°C, accounting for nucleoside monophosphate contributions.
• Analysis using the Ising linear model yielded enthalpy, entropy, and cooperativity factors for stacking interactions in both polymers.

Impact:

• Provides quantitative thermodynamic data for polyA and polyC stacking interactions, essential for molecular modeling and drug design.
• Establishes a methodology for detailed thermodynamic analysis of single nucleic acid chains.
• Contributes to a deeper understanding of DNA/RNA structural stability and flexibility.