Klebsiella pneumoniae nitrogenase: pre-steady-state absorbance changes show that redox changes occur in the MoFe protein that depend on substrate and component protein ratio; a role for P-centres in reducing dinitrogen?
- 15 May 1993
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 292 (1) , 93-98
- https://doi.org/10.1042/bj2920093
Abstract
The pre-steady-state absorbance changes that occur during the first 0.6 s of reaction of the nitrogenase of Klebsiella pneumoniae can be simulated by associating redox changes with the different states of the MoFe protein described by our published kinetic model for nitrogenase [Lowe and Thorneley (1984) Biochem. J. 224, 877-886]. When the substrate is changed, from H+ to C2H2 (acetylene) or N2, or the nitrogenase component protein ratio is altered, these pre-steady-state absorbance changes are affected in a manner that is quantitatively predicted by our model. The results, together with parallel e.p.r. studies, are interpreted as showing that the P-clusters become oxidized when the MoFe protein is in the state where bound N2 is irreversibly committed to being reduced and is protonated to the hydrazido(2-) level.Keywords
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