E. Argese et al., A POLAROGRAPHIC STUDY OF THE CATALYTIC MECHANISM OF THE IRON-CONTAINING SUPEROXIDE-DISMUTASE FROM ESCHERICHIA-COLI, Bioelectrochemistry and bioenergetics, 38(2), 1995, pp. 397-400
The dependence of the activity of iron-containing superoxide dismutase
from Escherichia coil on pH and ionic strength was investigated exten
sively in the ranges 7.7-11.0 and 0.02-0.25 M respectively. The result
s show that the enzymatic activity diminishes with both increasing pH
and increasing ionic strength, reaching a minimum value at about pH 11
. The activity decrease with increasing pH was ascribed to a gradual t
itration, by OH- ion, of the acid group Fe3+-H2O. This gives rise to a
deprotonated enzymatic form with a residual activity which is about 1
0% that of the protonated form. The dependence of the activity on ioni
c strength was interpreted as a Debye-Huckel effect.