The dynamical contact order: protein folding rate parameters based on quantum conformational transitions

Area of Science:

• Biophysics
• Quantum Chemistry

Background:

• Protein folding is a complex process crucial for biological function.
• Existing models often simplify the dynamics involved in protein conformational changes.

Purpose of the Study:

• To propose a new metric, dynamical contact order (DCO), for quantitatively analyzing protein folding rates.
• To validate the quantum theory of conformational dynamics in protein folding using experimental data.

Main Methods:

• Defined dynamical contact order (DCO) based on moment of inertia and torsion potential energy of polypeptide chains.
• Compared theoretical DCO calculations with experimental folding rate data for 80 diverse proteins.

Main Results:

• Established a correlation between protein folding rate and contact inertial moment.
• Demonstrated that multi-state protein folding exhibits quantum conformational transitions with a quantifiable time delay.
• Classified protein folding into exergonic (faster, two-state) and endergonic (slower, multi-state) types, with exergonic folding determining the speed limit.

Conclusions:

• Protein folding is a quantum conformational transition, supporting the quantum theory of conformational dynamics.
• DCO provides a robust method for quantitatively studying protein folding dynamics.
• Folding mechanisms can be categorized as exergonic or endergonic, influencing folding rates and protein types.