Turnover-dependent overoxidation of the conserved cysteine residue in the active site of water-forming NADH oxidases is the presumed cause of the limited nox2 stability.
A turnover-dependent kinetic assay, combined with the active-site titration approach of Ackermann and Potter, revealed that both M. tuberculosis enzymes had very low kcat values.
The turnover-dependent inactivation coupled to conformational change suggests a mechanism-based transformation that may provide a new probe of nitrogenase catalysis.
In the presence of divalent cations (Mg2 +, Ca2 +) or at alkaline pH, the turnover-dependent activation takes longer and the lag phase is more pronounced (Fig. 1A, DSH).
(i) The inactivation reaction, being turnover-dependent, suggests a process involving states of the MoFe-protein that are distinct from the as-isolated form, mostly likely a different redox state.
To understand the nature of the turnover-dependent interaction between LS and its substrate and to provide evidence for a potential intermediate in catalysis, we studied the Ec LS reaction with [8,8,8-H3]-OHP [8,8,8-H3]-OHP [8,8,8-H3]-OHP
In addition, slow turnover-dependent A to D conversion might involve dissociation of bound sodium ions from antiporter-like subunits in order for the enzyme to initialize H+-translocation machinery.
Turnover-dependent activation of complex I during NADH oxidation follows first-order kinetics [20], and therefore rate constant (kD → A) can be derived from the semilogarithmic plots as shown in Fig. 2C.
Together the findings indicate that the markers reflect lung pathology tissue turnover-dependent mechanisms in general, and that these mechanisms may be more pronounced in lung cancer (or a subgroup of lung cancers) as compared to the other lung pathologies (IPF + COPD) tested.
