RT Journal Article
SR Electronic
T1 Hydrogen Inhibition of Nitrogen Reduction by Nitrogenase in Isolated Soybean Nodule Bacteroids
JF Plant Physiology
JO Plant Physiol.
FD American Society of Plant Biologists
SP 663
OP 668
DO 10.1104/pp.91.2.663
VO 91
IS 2
A1 Rasche, Madeline E.
A1 Arp, Daniel J.
YR 1989
UL http://www.plantphysiol.org/content/91/2/663.abstract
AB Dihydrogen, a by-product of biological nitrogen fixation, is a competitive inhibitor of N2 reduction by nitrogenase. To evaluate the significance of H2 inhibition in vivo, we have measured the apparent inhibition constant for H2 inhibition of N2 reduction in Bradyrhizobium japonicum bacteroids isolated from soybean nodules. The rate of N2 reduction was measured as ammonia production by bacteroids incubated in a buffer containing 200 micromolar leghemoglobin and 10 millimolar succinate under 0.02 atmosphere O2 and various concentrations of N2 and H2. The apparent inhibition constant for H2 under these conditions was determined to be approximately 0.03 atmosphere. This relatively low value strengthens the proposal that H2 inhibition of N2 reduction may be a significant factor in lowering the efficiency of nitrogen fixation in legume nodules.