Protein destabilisation by ruthenium(II) tris-bipyridine based protein-surface mimetics

Area of Science:

• Biochemistry
• Chemical Biology
• Protein Science

Background:

• Cytochrome c (cyt c) plays crucial roles in cellular respiration and apoptosis.
• Developing selective sensors for proteins like cyt c is vital for biological research.
• Understanding protein-ligand interactions requires detailed analysis of conformational changes.

Purpose of the Study:

• To investigate the selective binding of a ruthenium(II) tris-bipyridine receptor (1) to equine cytochrome c (cyt c).
• To characterize the impact of this molecular recognition on cyt c's native protein conformation.
• To confirm the specificity of the observed effects through control experiments.

Main Methods:

• Synthesis and application of ruthenium(II) tris-bipyridine derivatives (receptors 1-3).
• Differential scanning calorimetry to assess protein thermal stability.
• Ion-mobility spectrometry (IMS) to probe conformational changes.
• Accelerated trypsin proteolysis assays to evaluate protein structure modifications.

Main Results:

• Receptor 1 selectively destabilized native equine cyt c by approximately 25 °C.
• Receptors 2 and 3 did not induce significant thermal destabilization, confirming specificity.
• The destabilizing effect was absent in 60% acetylated cyt c, demonstrating protein specificity.
• Ion-mobility spectrometry and accelerated trypsin proteolysis indicated conformational changes at room temperature due to molecular recognition.

Conclusions:

• Ruthenium(II) tris-bipyridine receptor 1 acts as a specific sensor for equine cyt c.
• Molecular recognition by receptor 1 induces significant conformational changes in cyt c.
• These findings highlight the potential of tailored receptors for probing protein structure and function.