Hamidinia SA, Tan
B, Erdahl WL, Chapman CJ, Taylor RW, Pfeiffer DR.
The ionophore nigericin transports Pb2+ with
high activity and selectivity: a comparison to monensin and
ionomycin.
Biochemistry. 2004 Dec
21;43(50):15956-65.
The K(+) ionophore nigericin is
shown to be highly effective as an ionophore for Pb(2+) but not
other divalent cations, including Cu(2+), Zn(2+), Cd(2+),
Mn(2+), Co(2+), Ca(2+), Ni(2+), and Sr(2+). Among this group a
minor activity for Cu(2+) transport is seen, while for the
others activity is near or below the limit of detection. The
selectivity of nigericin for Pb(2+) exceeds that of ionomycin or
monensin and arises, at least in part, from a high stability of
nigericin-Pb(2+) complexes. Plots of log rate vs log Pb(2+) or
log ionophore concentration, together with the pH dependency,
indicate that nigericin transports Pb(2+) via the species
NigPbOH and by a mechanism that is predominately electroneutral.
As with monensin and ionomycin, a minor fraction of activity may
be electrogenic, based upon a stimulation of rate that is
produced by agents which prevent the formation of transmembrane
electrical potentials. Nigericin-catalyzed Pb(2+) transport is
not inhibited by physiological concentrations of Ca(2+) or
Mg(2+) and is only modestly affected by K(+) and Na(+)
concentrations in the range of 0-100 mM. These characteristics,
together with higher selectivity and efficiency, suggest that
nigericin may be more useful than monensin in the treatment of
Pb intoxication.
PMID: 15595852
|
