Publication details
pH control of the reaction mechanism: interactions of the Au(i)-NHC complex with thioredoxin reductase (modeled by cysteine and selenocysteine); ab initio and DFT calculations
| Authors | |
|---|---|
| Year of publication | 2025 |
| Type | Peer-reviewed scientific article |
| Magazine / Source | Physical Chemistry Chemical Physics |
| MU Faculty or unit | |
| Citation | |
| web | https://pubs.rsc.org/en/content/articlelanding/2025/cp/d4cp04386c |
| Doi | https://doi.org/10.1039/d4cp04386c |
| Keywords | Addition reactions; Alkylation; Amino acids; Complexation; Coordination reactions; Gibbs free energy; pH |
| Description | Interactions of Cys and Sec amino acids with a simple model of the Au(i)-NHC complex were explored using DFT functionals and post-HF methods. In addition to the conventional quantum chemical description with the NVT canonical ensemble, a transformation to the grand-canonical ensemble was performed. This approach allowed for the consideration of chemical species with different numbers of protons and the evaluation of reactions at constant pH. For this purpose, a new thermodynamic state function, the Gibbs-Alberty free energy (Delta GA0), was introduced, with the proton chemical potential as the natural variable, and applied to Cys/Sec-Au(i)NHC interactions. Having determined all the necessary pKa values, the pH-dependent equilibrium constant was expressed for both Cys and Sec coordination to the gold(i) complex. The dependences of Delta GA0(Cys) and Delta GA0(Sec) as functions of varying pH demonstrated a clear preference for Sec coordination under acidic and neutral conditions, which shifted near pH approximate to 8, where Cys coordination became thermodynamically more stable. |