| Abstract | dc.description.abstract | Cu2? ions and reduced glutathione (GSH)
swiftly interact to form the physiologically occurring
Cu(I)–[GSH]2 complex. Prompted by the recently reported
ability of this complex to generate superoxide radicals from
molecular oxygen, the present study addressed how the
concentration of Cu2? and GSH, the pH, and the temperature
affect the formation of the Cu(I)–[GSH]2 complex
and its capacity to generate superoxide radicals and
hydrogen peroxide. Increasing concentrations of Cu2? and
GSH, added at a fixed molar ratio of 1:3, led to a proportionally
greater production of superoxide anions, hydrogen
peroxide, and oxidized glutathione (GSSG). GSSG formation
was found to closely reflect the formation of Cu(I)–
[GSH]2. Biologically relevant changes in pH (e.g., from 6.8
to 7.7) and temperature (from 22 to 37 C) did not affect
the formation of the Cu(I)–[GSH]2, as assessed by GSSG
production. However, production of superoxide radicals
increased as the pH values were incremented. An opposite
effect was observed regarding hydrogen peroxide production.
The ability of a freshly prepared Cu(I)–[GSH]2
complex (assayed within a minute from its formation) to
generate superoxide radicals was incremented by as the
temperature was increased. Such ability, however, correlated
inversely with the temperature when, before assaying
for superoxide, the earlier referred preparation was incubated
during 30 min in the presence of oxygen. Under the
latter condition, hydrogen peroxide linearly accumulated in
time, suggesting that an increased autodismutation underlies
the apparent time-dependent ‘‘aging’’ of the capacity of
the complex to generate superoxide. | en_US |
