Superoxide and peroxynitrite inactivate aconitases, but nitric oxide does not.

The Escherichia coli and recombinant human cytosolic aconitases are inactivated by O2-., with a rate constant of approximately 3 x 10(7) M-1 s-1; the corresponding value for the porcine mitochondrial aconitase is approximately 0.8 x 10(7) M-1 s-1. Nitric oxide, which is reported to inactivate aconitase, did not do so at a perceptible rate, while incubation with peroxynitrite led to a rapid loss of aconitase activity. We propose that the reported inactivation of aconitase by nitric oxide in vivo is actually mediated through peroxynitrite, the product of the reaction between O2-. and NO..