Oxidation kinetics with copper phenanthroline. The formation of procoat protein dimers with different times of phenanthroline exposure was studied. E. coli BL-21 cells bearing plasmids coding for procoat proteins H5/−6C (A), H5/−7C (B), and H5/−10C (C) were induced for 4 h. The cell membrane fraction was collected and exposed to 1 mM copper phenanthroline for the times indicated at the bottom of panel C. The reaction was stopped by addition of 10 mM EDTA and 10 mM NEM. The samples were acid precipitated and analyzed by nonreducing SDS-PAGE and Western blotting. Lane 1, samples pretreated with 100 mM DTT; lane 2, untreated samples (no CuP) (−PA); lanes 3 to 8, copper phenanthroline-treated samples; lane 9, same as lane 8 but samples were rereduced (rered) with 100 mM DTT. The arrows indicate the position of the procoat protein dimer.