M. Koutny et al., Evaluation of relative contributions of two enzymes supposed to metabolisehydrogen peroxide in Paracoccus denitrificans, BBA-BIOENER, 1410(1), 1999, pp. 71-76
A biosensor exploiting an electrochemically mediated enzyme-catalysed react
ion was used to quantify relative contributions of cytoplasmic catalase and
periplasmic cytochrome c peroxidase to the overall rate of hydrogen peroxi
de breakdown in cells of Paracoccus denitrificans. The effects of antimycin
(an inhibitor of electron flow to cytochrome c peroxidase), the reaction r
ate versus substrate concentration profiles for the whole cells and subcell
ular fractions, and the time courses of oxygen concentration demonstrated a
profound decrease in the capacity of cytochrome c peroxidase to reduce H2O
2 under in vivo conditions. The reason is suggested to be a competition for
available electrons between the enzyme and terminal oxidases metabolising
oxygen produced by catalase. (C) 1999 Elsevier Science B.V. All rights rese
rved.