Deciphering environment effects in peptide bond solvation dynamics by experiment and theory

Area of Science:

• Biophysics
• Physical Chemistry
• Computational Chemistry

Background:

• Proteins function in aqueous solutions, with water interactions critically influencing their structure and function.
• Conventional methods struggle to track individual water molecule motion due to bulk water averaging.
• Understanding protein hydration dynamics at the molecular level is essential for predicting protein behavior and designing new molecules.

Purpose of the Study:

• To elucidate the atomistic details of water rearrangement dynamics around the -CONH- peptide linkage.
• To investigate the impact of a minor structural modification (methyl group presence) on solvation dynamics.
• To establish a link between kinetic energy redistribution and solvent migration timescales.

Main Methods:

• Utilized picosecond pump-probe time-resolved infrared spectroscopy.
• Employed molecular dynamics simulations for detailed atomistic analysis.
• Compared solvation dynamics in formanilide and acetanilide model systems.

Main Results:

• Demonstrated that a small structural difference in peptide linkages profoundly influences solvation dynamics at the molecular level.
• Identified kinetic energy redistribution efficiency as the primary determinant of solvent migration timescales, rather than potential energy surface shape.
• Provided a detailed atomistic picture of water rearrangement dynamics.

Conclusions:

• The study offers fundamental insights into protein hydration and solvation dynamics.
• Highlights the sensitivity of molecular-level water dynamics to subtle structural variations.
• Suggests potential for designing functional molecules with tailored solution properties based on hydration dynamics.