A Maximum Caliber analysis of the Foldon Hypothesis

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Protein folding models propose different mechanisms, including defined pathways (e.g., Foldon Hypothesis) and heterogeneous pathways.
• The Foldon Hypothesis posits protein folding occurs via stepwise assembly of cooperative units called foldons.

Purpose of the Study:

• To test the Foldon Hypothesis by analyzing protein folding mechanisms.
• To investigate whether protein folding follows a dominant, defined pathway or a heterogeneous set of pathways.

Main Methods:

• Application of the Maximum Caliber (Max Cal) method to analyze folding dynamics.
• Utilizing experimental folding data for the protein cytochrome c (cyt c).
• The Max Cal method calculates probabilities for dynamical trajectories, analogous to the maximum entropy principle for equilibrium states.

Main Results:

• Analysis of cytochrome c folding data using the Max Cal method.
• The results suggest that a dominant, defined folding pathway is not required by the data.
• Evidence points towards a heterogeneous folding process for cytochrome c, involving multiple pathways.

Conclusions:

• The study challenges the necessity of a single, defined pathway in protein folding.
• The folding of cytochrome c is likely a complex, heterogeneous process with multiple contributing pathways.
• Findings suggest that protein folding mechanisms may be more varied than proposed by strictly defined pathway models.