Construction and Characterization of a Novel Direct Electron Transfer Type Enzymatic Sensor Using Spermidine...

Area of Science:

• Biochemistry
• Electrochemistry
• Biosensors

Background:

• Spermidine dehydrogenase (SpDH) is an enzyme crucial for polyamine metabolism.
• Direct electron transfer (DET) in enzymes is key for developing efficient biosensors.
• Spermine is a polyamine with significant physiological roles, and its detection is important.

Purpose of the Study:

• To investigate the direct electron transfer (DET) capability of spermidine dehydrogenase (SpDH).
• To develop a DET-type enzymatic sensor for spermine detection using immobilized SpDH.

Main Methods:

• Immobilization of SpDH onto a gold electrode using a self-assembled monolayer.
• Cyclic voltammetry and chronoamperometry for electrochemical analysis.
• Spectroscopic analysis to confirm internal electron transfer.

Main Results:

• SpDH confirmed to exhibit DET, with internal electron transfer from FAD to heme b.
• An SpDH-modified electrode showed increased oxidation current in the presence of spermine.
• The developed sensor demonstrated a linear response to spermine from 0.2 to 2.0 µM with a low limit of detection (0.084 µM).

Conclusions:

• SpDH possesses intrinsic DET ability, enabling its use in electrochemical sensors.
• The SpDH-based sensor is effective for detecting physiologically relevant spermine concentrations.
• Conserved histidine residues in SpDH homologs suggest potential for DET in related enzymes.