Kinetic data for Klebsiella pneumoniae nitrogenase were used to determine the values of nine of the 17 rate constants that define the scheme for nitrogenase action described by Lowe & Thorneley [(1984) Biochem. J. 224, 877-886]. Stopped-flow spectrophotometric monitoring of the MgATP-induced oxidation of the Fe protein (Kp2) by the MoFe protein (Kp1) was used to determine the rates of association (k+1) and dissociation (k-1) of reduced Kp2(MgATP)2 with Kp1. The dependences of the apparent KNm2 on Fe protein/MoFe protein ratio and H2 partial pressure were used to determine the mutual displacement rates of N2 and H2 (k+10, k-10, k+11 and k-11). These data also allowed the rate constants for H2 evolution from progressively more reduced forms of Kp1 to be determined (k+7, k+8 and k+9). A mechanism for N2-dependent catalysis of 1H2H formation from 2H2 that requires H2 to be a competitive inhibitor of N2 reduction is also presented.
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December 1984
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Research Article|
December 15 1984
The mechanism of Klebsiella pneumoniae nitrogenase action. The determination of rate constants required for the simulation of the kinetics of N2 reduction and H2 evolution
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1984 London: The Biochemical Society
1984
Biochem J (1984) 224 (3): 895–901.
Citation
D J Lowe, R N F Thorneley; The mechanism of Klebsiella pneumoniae nitrogenase action. The determination of rate constants required for the simulation of the kinetics of N2 reduction and H2 evolution. Biochem J 15 December 1984; 224 (3): 895–901. doi: https://doi.org/10.1042/bj2240895
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