Stoichiometric production of hydrogen peroxide and parallel formation of ferric multimers through decay of the diferric-peroxo complex, the first detectable intermediate in ferritin mineralization.

The catalytic step that initiates formation of the ferric oxy-hydroxide mineral core in the central cavity of H-type ferritin involves rapid oxidation of ferrous ion by molecular oxygen (ferroxidase reaction) at a binuclear site (ferroxidase site) found in each of the 24 subunits. Previous investigators have shown that the first detectable reaction intermediate of the ferroxidase reaction is a diferric-peroxo intermediate, F(peroxo), formed within 25 ms, which then leads to the release of H(2)O(2) and formation of ferric mineral precursors. The stoichiometric relationship between F(peroxo), H(2)O(2), and ferric mineral precursors, crucial to defining the reaction pathway and mechanism, has now been determined.

[Overexpression and its clinical significance of multi-drug resistance associated genes in lung cancer tissues].

Background: To investigate the expression level and its clinical significance of the multi-drug resistance (MDR) associated protein in lung cancer specimens.

Methods: The expression levels of Pgp, MRP, GST-π and TopoII of MDR associated protein were detected in 60 lung cancer samples and 30 paracancerous tissues by S-P immunohistochemistry method.

Results: The positive rate of Pgp, MRP, GST-π and Topo II in the lung cancer tissues was 40.