Pulsed electron paramagnetic resonance studies of the interaction of Mg-ATP and D2O with the iron protein of nitrogenase.
Mg-ATP binds to the iron protein component of nitrogenase. The magnetic field dependence of the linear electric field effect (LEFE) in pulsed EPR is consistent with a single 4Fe-4S cluster. The LEFE is virtually unaltered when Mg-ATP is bound. Electron spin echo envelope modulation techniques were employed to evaluate the possibility of a magnetic interaction between 31P of Mg-ATP and the Fe-S center of the iron protein. None was detected. However, weak modulations possibly attributable to peptide 14N were seen, and these were slightly shifted by Mg-ATP addition. Further, protons in the vicinity of the Fe-S cluster of the protein readily exchange with D2O, and this process is unaffected by Mg-ATP.
Morgan
T V
TV
University of Georgia, Center for Metalloenzyme Studies, Athens, Georgia 30602.
McCracken
J
J
Orme-Johnson
W H
WH
Mims
W B
WB
Mortenson
L E
LE
Peisach
J
J
D000255:Adenosine Triphosphate / Q000378:metabolism*; D001395:Azotobacter / Q000201:enzymology; D003013:Clostridium / Q000201:enzymology; D003903:Deuterium; D017666:Deuterium Oxide; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D007700:Kinetics; D008667:Metalloproteins / Q000378:metabolism*; D009591:Nitrogenase / Q000378:metabolism*; D011485:Protein Binding; D014867:Water
D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D014867:Water; D000255:Adenosine Triphosphate; D003903:Deuterium; D009591:Nitrogenase; D017666:Deuterium Oxide