Spectroscopic and kinetic investigation of the reactions of peroxyacetic acid with Burkholderia pseudomallei catalase-peroxidase, KatG.

Catalase-peroxidases or KatGs can utilize organic peroxyacids and peroxides instead of hydrogen peroxide to generate the high-valent ferryl-oxo intermediates involved in the catalase and peroxidase reactions. In the absence of peroxidatic one-electron donors, the ferryl intermediates generated with a low excess (10-fold) of peroxyacetic acid (PAA) slowly decay to the ferric resting state after several minutes, a reaction that is demonstrated in this work by both stopped-flow UV–vis absorption measurements and EPR spectroscopic characterization of Burkholderia pseudomallei KatG (BpKatG). EPR spectroscopy showed that the [FeIV═O Trp330•+], [FeIV═O Trp139•], and [FeIV═O Trp153•] intermediates of the peroxidase-like cycle of BpKatG (Colin, J.Wiseman, B.Switala, J.Loewen, P. C.Ivancich, A. (2009) J. Am. Chem. Soc. 131, 8557−8563), formed with a low excess of PAA at low temperature, are also generated with a high excess (1000-fold) of PAA at room temperature. However, under high excess conditions, there is a ra...