Reactions of R5P with bovine heart cytochrome c and with Lys at 37 °C and pH 7.5 generate products that can reduce ferri-cytochrome c. Concentrations of reactants: cytochrome c (1 mg/mL; 82 μM), R5P (10 mM), and Lys (100 mM). Cytochrome c alone (○—○); cytochrome c and R5P (■—■); cytochrome c, R5P, and SOD (76 U/mL) (◆ - - ◆); cytochrome c, R5P, and Lys (▲- - ▲).