Figure 8. M. tuberculosis APS Reductase Cys249Ser Mutant Enzyme Binds APS, but Does Not Form a Covalent Intermediate.

ESI mass spectra of 20 μM Cys249Ser APS reductase with 20 μM APS (A) and wild-type enzyme (B) with 5 μM APS in 50 mM NH₄OAc (pH 7.5). Insets: The corresponding deconvoluted spectra acquired in 80% acetonitrile showing the presence and absence of a covalent modification to the mutant and wild-type enzymes, respectively.