Inhibitors have been essential in studying the sequence of events in electron tr
ID: 175108 • Letter: I
Question
Inhibitors have been essential in studying the sequence of events in electron transport system. As part of the experimental investigation of this sequence of events, rotenone has been useful as a specific inhibitor of one of the seven components shown above. Explain how p-hydroxybutyrate concentration will change when rotenone is mixed with mitochondria in the presence of beta-hydroxybutyrate and NADH. (mitochondria contain beta-hydroxybutyrate dehydrogenase enzyme that can convert beta-hydroxybutyrate to acetoacetate.)Explanation / Answer
Rotenone is an odorless, colorless and crystalline isoflavone insecticide.
In mitochondria, it interferes with the electron transport chain by inhibiting the oxidation NADH to NAD. Rotenone acts as complex-I inhibitor of the respiratory chain. It inhibits the transfer of electrons from iron-sulfur centers in complex I to coenzyme Q.
In mitochondria, beta hydroxybutyrate is converted to acetoacetate by the enzyme beta hydroxybutyrate dehydrogenase. The reversal of this also takes place by using NAD as hydrogen acceptor. Since, rotenone reduced the level of NAD in mitochonadria, this in turn will lead to decreased concentration of beta hydroxybutyrate in mitochondria.