MATERIALS & METHODS Materials: Tetrakis(4-sulfonatophenyl)porphyrin (TPPS), Zn(II)TPPS, Mn(III)TPPS, Tetrakis(4-carboxyphenyl)porphyrin (TPPC), Zn(II)TPPC, and Mn(III)TPPC were purchased from Frontier Scientific, Inc (Logan, UT). NAD+, triethanolamine (TEOA), 慣-ketoglutarate, ammonium sulfate, and glutamate dehydrogenase (GDH) were purchased from Sigma- Aldrich (St. Louis, MO). All chemicals were used without further purification. M was synthesized according to the literature (Lee et al., 2009).....