Electrochemical studies on nitrite reductase towards a biosensor

Area of Science:

• Biochemistry
• Electrochemistry
• Enzyme catalysis

Background:

• Nitrite reductase (NiR) is a c-type hexaheme enzyme.
• Desulfovibrio desulfuricans (Dd) NiR catalyzes the six-electron reduction of nitrite to ammonia.
• Previous studies indicated a simple electrocatalytic mechanism for this enzyme.

Purpose of the Study:

• To investigate the potential of Dd NiR as a biosensor component.
• To characterize the electrochemical behavior of gel-immobilized Dd NiR.
• To determine the substrate dependence of the enzyme's amperometric response to nitrite.

Main Methods:

• Isolation of c-type hexaheme nitrite reductase from Desulfovibrio desulfuricans.
• Immobilization of the enzyme onto a glassy carbon electrode.
• Electrochemical characterization, including cyclic voltammetry and amperometry.
• Analysis of enzyme kinetics using Michaelis-Menten models.

Main Results:

• Gel-immobilized Dd NiR exhibited enzymatic activity and amperometric response to nitrite.
• The catalytic current density was dependent on nitrite concentration.
• The enzyme's response followed Michaelis-Menten-type substrate dependence.
• The NiR-electrode demonstrated potential for analytical nitrite determination.

Conclusions:

• Desulfovibrio desulfuricans NiR is a suitable candidate for biosensor development due to its substrate specificity, availability, and stability.
• The NiR-electrode can be used for the analytical determination of nitrite in complex media.
• Electrochemical immobilization of NiR provides a viable platform for biosensing applications.