Light-driven dinitrogen reduction catalyzed by a CdS:nitrogenase MoFe protein biohybrid

Area of Science:

• Biochemistry
• Materials Science
• Chemical Engineering

Background:

• Dinitrogen (N2) reduction to ammonia (NH3) is crucial for life but energetically demanding.
• The Haber-Bosch process requires high temperatures and pressures.
• Nitrogenase enzyme performs N2 fixation under ambient conditions using adenosine 5 -triphosphate (ATP) hydrolysis.

Purpose of the Study:

• To investigate the use of cadmium sulfide (CdS) nanocrystals to photosensitize the nitrogenase molybdenum-iron (MoFe) protein.
• To replace ATP hydrolysis with light harvesting for N2 reduction.
• To establish a photochemical model for light-driven ammonia synthesis.

Main Methods:

• Utilizing cadmium sulfide (CdS) nanocrystals to coat the nitrogenase molybdenum-iron (MoFe) protein.
• Employing light energy to drive the enzymatic reduction of N2 to NH3.
• Assessing the turnover rate and effect of nitrogenase inhibitors.

Main Results:

• Cadmium sulfide (CdS) nanocrystals successfully photosensitized the nitrogenase MoFe protein.
• Light harvesting by CdS replaced ATP hydrolysis for N2 reduction to NH3.
• The observed turnover rate was 75 per minute, achieving 63% of the ATP-coupled rate.
• Inhibitors like acetylene, carbon monoxide, and dihydrogen suppressed N2 reduction.

Conclusions:

• CdS:MoFe protein biohybrids demonstrate a viable photochemical pathway for N2 reduction.
• This approach offers a potential alternative to traditional ammonia synthesis methods.
• The study provides a new model for light-driven biological catalysis.