Dinitrophenol inhibiting ATP production. Animation showing the mechanism by which 2, 4 dinitrophenol (DNP) inhibits the production of ATP (adenosine triphosphate). This mechanism involves the uncoupling of the normal electron transport chain. The normal process is shown in this animation, with the effect of DNP shown at the end. This mechanism occurs in cell organelles called mitochondria (one at bottom left). Mitochondria produce and store energy obtained in respiration. The inner mitochondrial membrane is shown with embedded proteins and complexes. The electron transport chain shown here starts with a reduced form of nicotinamide adenine dinucleotide (NADH2, top left). The electrons (blue) are transferred to NADH dehydrogenase (orange), with two protons (green) moving from inside to outside the mitochondrion (matrix to intermembrane space). The next stage is transfer of the electrons to the cytochrome b-c1 complex (red), with further transfer of an electron to cytochrome oxidase (green), and then onwards to oxygen (O2, top right). This produces water (H2O, blue) with protons passing through the proton pump (bottom right). At the proton pump, ATP is synthesised, with adenosine diphosphate (ADP) and inorganic phosphate (Pi) also shown. In the re-run of this sequence, DNP (large white oval) is a hydrophobic substance and inserts into the membrane's phospholipid bilayer to act as a proton transporter. Like other uncouplers, it short-circuits the proton concentration gradient and the electric potential across the inner mitochondrial membrane, converting the energy released by NADH2 oxidation to heat. For this animation without labels, see K004/3316. |