Figure 1.

Kinetic characterization of ProDH activity in isolated mitochondria (A,B), and the effect of proline concentration on oxygen consumption rates (LEAK: red bars; OXPHOS: green bars) of isolated mouse liver (C–G) and kidney (H–L) mitochondria using various substrate combinations and concentrations. (A) ProDH catalytic activity content (expressed in pkat/mg) of mitochondria isolated from mouse liver, kidney, brain, and heart using saturating concentrations of proline (100 mM) * p < 0.05 (comparing all groups with each other; ANOVA on Ranks). Data are SEM averaged from three independent experiments. (B) Determination of apparent K_m of mouse liver ProDH for proline. Data points are SEM averaged from three independent experiments. (C,H) Rox: residual oxygen consumption (no external substrate added; increased OXPHOS indicates the effect of ADP stimulating respiration on internal substrates), followed by proline titrations. (D,I) GM: glutamate and malate, followed by proline titrations. (E) GM and 2 mM βOH, followed by proline titration. (J) GM: glutamate and malate, 2 mM Itac: GM+2 mM itaconate, followed by proline titration. (F,K,G,L) Proline (Pro) and/or succinate (S). Data are SEM averaged from at least three independent experiments. For C–L, * p < 0.05 (ANOVA Bonferroni [comparisons are to controls, i.e., no proline] or on ranks, if normality failed).