A simple method to identify supramolecules in action: Hill coefficients for exergonic self-assembly

Area of Science:

• Supramolecular Chemistry
• Biophysical Chemistry
• Materials Science

Background:

• Precise supramolecular architecture is crucial for molecular function.
• Existing methods struggle to reliably detect supramolecular structures and functions in complex systems at relevant concentrations.
• Traditional Hill plots are incompatible with exergonic self-assembly, a common and stable form of supramolecular organization.

Purpose of the Study:

• To develop a reliable and rapid method for demonstrating supramolecular structure and function in complex systems.
• To adapt Hill plot analysis for the accurate characterization of exergonic self-assembly.
• To validate the new method using a relevant example of functional supramolecular architecture.

Main Methods:

• Utilized chemical denaturation to artificially increase monomer concentration.
• Applied modified Hill plots to analyze the dependence of spectroscopic signals on monomer concentration.
• Employed circular dichroism (CD) spectroscopy for sensitive and selective detection of supramolecular structures.

Main Results:

• Demonstrated that chemical denaturation restores compatibility of Hill plots with exergonic self-assembly.
• Achieved Hill coefficients (n > 1) indicating stable supramolecular formation.
• Successfully applied the method to a rigid-rod pi-stack architecture with photosynthetic and ion channel activity.

Conclusions:

• The developed method enables accurate detection and characterization of stable supramolecular structures and functions.
• This approach overcomes limitations of traditional Hill plot analysis for exergonic self-assembly.
• The findings provide a valuable tool for studying complex supramolecular systems in various scientific fields.