Myoglobin as an efficient electrocatalyst for nitromethane reduction.

Area of Science:

• Biochemistry
• Electrochemistry
• Environmental Science

Background:

• Heme enzymes are crucial for metabolizing xenobiotics, including carcinogens like nitro compounds.
• Catalytic electron transfer reactions, particularly under anaerobic conditions, are key to this activation process.

Purpose of the Study:

• To investigate myoglobin (Mb) as a model heme enzyme for the electrocatalytic reduction of nitromethane.
• To elucidate the mechanism of Mb-mediated nitro compound reduction in surfactant films.

Main Methods:

• Cyclic voltammetry was used to characterize the electrocatalytic process.
• Spectroscopic methods identified a Mb-Fe(II)-nitrosomethane intermediate.
• Bulk electrolysis determined the end product of the reaction.

Main Results:

• Myoglobin demonstrated efficient electrocatalysis for nitromethane reduction in thin surfactant films.
• A Mb-Fe(II)-nitrosomethane complex was spectroscopically characterized as a potential intermediate.
• Methylhydroxylamine was identified as the primary aqueous product.

Conclusions:

• Myoglobin functions as an effective electrocatalyst for nitro compound reduction.
• The catalytic mechanism involves the reduced Fe(I) state of myoglobin facilitating inner-sphere electron and proton transfers.
• This research provides insights into the role of heme enzymes in carcinogen activation.