Free energy perturbation techniques applied to subtilisin BPN' stability

Area of Science:

• Protein Engineering
• Computational Biophysics

Background:

• Predicting mutation effects on protein stability is crucial for protein engineering.
• Small changes in free energy (5-15 kcal/mol) differentiate native and denatured protein states, complicating rational design.
• Accurate prediction of mutation-induced stability changes remains a significant challenge.

Purpose of the Study:

• To evaluate the utility of Free Energy Perturbation Technique (FEPT) for predicting protein stability changes.
• To identify key atomic contributions to stability changes upon mutation.
• To explore the application of FEPT in rational protein design, specifically for subtilisin BPN'.

Main Methods:

• Utilized the Free Energy Perturbation Technique (FEPT) computational method.
• Employed the CHARMm program for simulations.
• Applied FEPT to analyze specific mutations in subtilisin BPN', including Asn to Ser at residue 218 and mutations at residue 203.

Main Results:

• FEPT was applied to known stabilizing mutations in subtilisin BPN', demonstrating its capability to evaluate potential mutation sites.
• The study analyzed atomic contributions to increased protein stability.
• FEPT's predictive power was tested using mutations at residue 203, highlighting the need for adequate conformational sampling for accuracy.

Conclusions:

• FEPT is a valuable computational tool for protein engineering, enabling the evaluation of mutations prior to synthesis.
• The technique identifies critical atomic interactions influencing protein stability.
• While accuracy and speed are limitations, FEPT's insights into structure, energy, dynamics, and solvent effects make it attractive for designing more stable proteins like subtilisin BPN'.