FIG. 5.

Cationic manganoporphyrins stimulate NADPH oxidation by human cytochrome P450 reductase. Human recombinant cytochrome P450 reductase and NADPH (250 μM) is incubated in the presence of increasing concentrations of either MnTDEIP⁵⁺ or MnTEPyP⁵⁺ and NADPH oxidation is followed spectrophotometrically at 340 nm for 1 min. Each value is performed in triplicate and data are presented as their mean ± SEM. (A) Both MnTEPyP⁵⁺ and MnTDEIP⁵⁺ stimulated cytochrome P450 reductase oxidation of NADPH. (B) Lineweaver-Burke plot of data reveals a lower Km and higher Vmax for MnTEPyP⁵⁺ than MnTDMEIP⁵⁺.