Gels were removed from the glass plates and submerged in a staining solution containing 200 mM Tris (pH 7.9), 0.4 mM NADP+, 15 mM MgCl2, 8 mM isocitrate, 0.4 mM 3-(4,5-dimethyl-2-thiazolyl)-2,5 diphenyl- 2H-tetrazolium bromide, and 0.5 mM phenazine methosulfate.