Recent advances in biosynthetic modeling of nitric oxide reductases and insights gained from nuclear resonance vibrational and other spectroscopic studies.
This Forum Article focuses on recent advances in structural and spectroscopic studies of biosynthetic models of nitric oxide reductases (NORs). NORs are complex metalloenzymes found in the denitrification pathway of Earth's nitrogen cycle where they catalyze the proton-dependent two-electron reduction of nitric oxide (NO) to nitrous oxide (N2O). While much progress has been made in biochemical and biophysical studies of native NORs and their variants, a clear mechanistic understanding of this important metalloenzyme related to its function is still elusive. We report herein UV-vis and nuclear resonance vibrational spectroscopy (NRVS) studies of mononitrosylated intermediates of the NOR reaction of a biosynthetic model. The ability to selectively substitute metals at either heme or nonheme metal sites allows the introduction of independent (57)Fe probe atoms at either site, as well as allowing the preparation of analogues of stable reaction intermediates by replacing either metal with a redox inactive metal. Together with previous structural and spectroscopic results, we summarize insights gained from studying these biosynthetic models toward understanding structural features responsible for the NOR activity and its mechanism. The outlook on NOR modeling is also discussed, with an emphasis on the design of models capable of catalytic turnovers designed based on close mimics of the secondary coordination sphere of native NORs.
Saumen
S
Chakraborty
Julian
J
Reed
Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States.
J Timothy
JT
Sage
Department of Physics, Northeastern University , Boston, Massachusetts 02115, United States.
Nicole C
NC
Branagan
Igor D
ID
Petrik
Kyle D
KD
Miner
Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States.
Michael Y
MY
Hu
Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States.
Jiyong
J
Zhao
Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States.
E Ercan
EE
Alp
Yi
Y
Lu
D008958:Models, Molecular; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D009609:Nitrous Oxide / Q000737:chemistry / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet
D009569:Nitric Oxide; D010088:Oxidoreductases; C034747:nitric-oxide reductase; D009609:Nitrous Oxide