1. C206, T107, and R278 are the crucial residues for H2O2 catalysis.
C206, T107, and R278 are the crucial residues for H2O2 catalysis. (A) In the crystal structure of Cg-OxyRH2O2, an H2O2 molecule occupies the active-site pocket in two of the four chains present in the asymmetric unit. Displayed is one of the two the H2O2 binding environments, termed pocket A (see Crystallographic and Kinetic Evidence for H2O2 Binding and Reduction). Here, the side-chain of S206 is directed away from the active site, whereas in pocket B, the side-chain of S206 is directed into the active site. Both conformations are displayed here, with a double-headed arrow indicating the rotameric change. The hydrogen-bonding network between H2O2, two conserved water molecules, and residues of the active site is expressed in terms of interatomic distances. (B) Mutation of the active-site residues impairs H2O2 reduction and supports the crystallographic data. WT Cg-OxyR and mutant variants (C206S, T107V, T136V, H205A, R278Q) were mixed with an equimolar amount of H2O2, and the H2O2 concentration was monitored in function of time with the FOX assay reagent. The lines correspond to single exponential fittings of the H2O2 consumption (n = 3). The error bars correspond to SD.
Brandán Pedre et al. PNAS doi: /pnas
©2018 by National Academy of Sciences