Solvent effect on hydrogen bonded Tyr⋯Asp⋯Arg triads: Enzymatic catalyzed model system

Area of Science:

• Computational Chemistry
• Biophysical Chemistry
• Quantum Chemistry

Background:

• Hydrogen bonds are fundamental to molecular structure, enzyme function, and material properties.
• Understanding solvent and electronic influences on hydrogen bonds is key to predicting molecular behavior.

Purpose of the Study:

• To investigate the impact of solvent and electronic effects on hydrogen bonds within specific molecular triads.
• To elucidate the mechanisms of proton and electron transfer in these systems.

Main Methods:

• Utilizing the polarizable continuum model (PCM) with B3LYP/6-311++G(d,p) level of theory.
• Performing geometry optimizations to analyze structural and electronic changes.
• Examining Infrared (IR) spectra, chemical shifts, and spin-spin coupling constants.

Main Results:

• Proton transfer from tyrosyl occurs spontaneously upon oxidation in both gas and solvent phases.
• Electron transfer isomers are observed for anionic triads, irrespective of the solvent.
• Solvent effects enlarge hydrogen bond distances and stabilize the system, increasing ionization potential and electron affinity.

Conclusions:

• Solvent and electronic effects profoundly influence hydrogen bond dynamics and reactivity.
• Oxidation of tyrosyl and electron binding to arginine are favored under investigated conditions.
• Electronic effects on spectral properties are more pronounced than solvent dielectric constant variations.