Figure 4.

In vitro inhibition of OGDHC and OADHC from the rat heart and liver by 0.01 mM phosphonate analogues of 2-oxodicarboxylates at physiologically relevant concentrations of 2-oxo substrates. (A) The 2-oxo acid substrates and their phosphonate analogues. (B) Inhibition of the rates of the OADH reaction at 0.01 or 0.02 mM 2-oxoadipate (2-OA) by 0.01 mM succinyl, glutaryl or adipoyl phosphonates (SP, GP or AP, correspondingly). (C) Inhibition of the rates of the OGDH or OADH reactions at 0.2 mM 2-oxoglutarate (2-OG) or 2-oxoadipate (2-OA) by 0.01 mM SP, GP or AP. The reactions were started by the enzyme addition to the reaction medium. App. 40 µg or 65 µg of protein of the heart or liver preparations, correspondingly, was added per well. The control (Ctrl) reaction rates were measured in the media omitting the inhibitors. The lower reaction rates (with 0.01 (B) or 0.2 mM (C) 2-OA) and corresponding significant differences are depicted with lighter shades of the same colours. Statistical significances were analysed by one-way ANOVA for multiple groups comparison, followed by Tukey’s post-hoc test. For the simplicity of the presentation, only the significant differences (p ≤ 0.05) vs the control reaction rates are shown by asterisks.