Ring complexes of S-nitrosothiols with CU+: a density functional theory study

Area of Science:

• Computational chemistry
• Biochemistry
• Inorganic chemistry

Background:

• Nitrosylated cysteine (CysNO) plays a role in biological signaling.
• Copper ions (Cu+) are essential metal ions involved in various biological processes.
• Understanding the interaction between metal ions and S-nitrosothiols is crucial for elucidating their chemical behavior.

Purpose of the Study:

• To investigate the complex formation between Cu+ and nitrosylated cysteine (CysNO) and its derivatives using computational methods.
• To compare the stability and structural properties of different coordination modes.
• To assess the influence of water molecules on the complex stability.

Main Methods:

• Density Functional Theory (DFT) calculations using the B3P86/6-311+G(2df,p) method.
• Optimization of complex structures.
• Calculation and comparison of relative enthalpies and free energies.

Main Results:

• The most stable complexes are formed when Cu+ coordinates to the sulfur atom of the SNO group in CysNO derivatives.
• Coordination to sulfur leads to significant lengthening of the S-N bond and shortening of the N-O bond.
• Coordination to nitrogen results in the opposite effect: shortening of the S-N bond and lengthening of the N-O bond.
• The presence of other coordinating functional groups and the coordination state of Cu+ modulate these effects.

Conclusions:

• The coordination site of Cu+ on the SNO group dictates the structural changes within the nitrosothiol moiety.
• DFT calculations provide valuable insights into the bonding preferences and stability of metal-S-nitrosothiol complexes.
• These findings contribute to understanding the chemistry of S-nitrosothiols in biological systems involving copper.