Light-driven dinitrogen reduction catalyzed by a CdS:nitrogenase MoFe protein biohybrid.
The splitting of dinitrogen (N2) and reduction to ammonia (NH3) is a kinetically complex and energetically challenging multistep reaction. In the Haber-Bosch process, N2 reduction is accomplished at high temperature and pressure, whereas N2 fixation by the enzyme nitrogenase occurs under ambient conditions using chemical energy from adenosine 5'-triphosphate (ATP) hydrolysis. We show that cadmium sulfide (CdS) nanocrystals can be used to photosensitize the nitrogenase molybdenum-iron (MoFe) protein, where light harvesting replaces ATP hydrolysis to drive the enzymatic reduction of N2 into NH3 The turnover rate was 75 per minute, 63% of the ATP-coupled reaction rate for the nitrogenase complex under optimal conditions. Inhibitors of nitrogenase (i.e., acetylene, carbon monoxide, and dihydrogen) suppressed N2 reduction. The CdS:MoFe protein biohybrids provide a photochemical model for achieving light-driven N2 reduction to NH3.
Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.
Katherine A
KA
Brown
Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
Derek F
DF
Harris
Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA.
Molly B
MB
Wilker
Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
Andrew
A
Rasmussen
Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
Nimesh
N
Khadka
Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA.
Hayden
H
Hamby
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA.
Stephen
S
Keable
Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA.
Gordana
G
Dukovic
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA.
John W
JW
Peters
Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
Lance C
LC
Seefeldt
Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA. paul.king@nrel.gov.
Paul W
PW
King
D000255:Adenosine Triphosphate / Q000737:chemistry; D000641:Ammonia / Q000737:chemistry; D019187:Cadmium Compounds / Q000737:chemistry*; D002384:Catalysis / Q000528:radiation effects; D006868:Hydrolysis / Q000528:radiation effects; D008027:Light; D008983:Molybdoferredoxin / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry*; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000737:chemistry* / Q000528:radiation effects; D010084:Oxidation-Reduction / Q000187:drug effects / Q000528:radiation effects; D013440:Sulfides / Q000737:chemistry*
D019187:Cadmium Compounds; D008983:Molybdoferredoxin; D013440:Sulfides; C034939:cadmium sulfide; D000641:Ammonia; D000255:Adenosine Triphosphate; D009591:Nitrogenase; D009584:Nitrogen