Switchable "On-Off" electrochemical technique for detection of phosphorylation

Area of Science:

• Electrochemistry
• Biochemistry
• Biosensors

Background:

• Phosphorylation is a key post-translational modification regulating protein function.
• Protein kinase A (PKA) plays a crucial role in various cellular signaling pathways.
• Sensitive detection of PKA activity is essential for understanding cellular processes and disease mechanisms.

Purpose of the Study:

• To develop a simple, ultrasensitive electrochemical method for detecting phosphorylation.
• To establish a robust assay for quantifying protein kinase A (PKA) activity.
• To demonstrate the method's applicability in complex biological samples like serum.

Main Methods:

• Utilized self-assembled monolayers (SAMs) of substrate peptides on an electrode surface.
• Employed a positively charged electrochemical probe, [Ru(NH3)5Cl]2+, to monitor changes in SAM structure.
• Monitored electrochemical signal changes corresponding to phosphorylation events and PKA activity.

Main Results:

• Achieved an "Off" state due to blocked probe access by the compact SAM.
• Observed an "On" state signal upon phosphorylation-induced SAM loosening and probe access.
• Demonstrated reversible switching between "On" and "Off" states via PKA and alkaline phosphatase.
• Determined an exceptionally low detection limit of 1×10⁻⁴ unit/mL for PKA activity.
• Established a wide linear range for PKA activity assay from 1×10⁻⁴ to 1×10⁻² unit/mL.

Conclusions:

• The developed electrochemical method offers ultrasensitive detection of phosphorylation and PKA activity.
• The assay exhibits high specificity and reproducibility, even in serum samples.
• This approach provides a valuable tool for biochemical research and clinical diagnostics.