Final answer:
Oligomycin is the drug that inhibits Complex V or ATP synthase in the electron transport chain. It binds to the Fo subunit, blocking proton flow and stopping ATP synthesis. Understanding these inhibitors is crucial for exploring mitochondrial function and drug interactions.
Step-by-step explanation:
Inhibitors of the Electron Transport Chain (ETC) and Complex V
The student asks which drug inhibits Complex V of the electron transport chain (ETC). The ETC consists of a series of complexes that transfer electrons and pump protons to establish a gradient used for ATP synthesis. While the question specifies Complex V, commonly known inhibitors of ETC components include rotenone and barbital for Complex I and antimycin-A for Complex III. Complex IV can be inhibited by cyanide, carbon monoxide, and H₂S gas. However, oligomycin is known to specifically inhibit Complex V, also known as ATP synthase, thereby halting ATP production.
Oligomycin works by binding to the Fo subunit of ATP synthase, blocking proton flow through the complex, and effectively stopping ATP synthesis as protons cannot return to the mitochondrial matrix. This is because Complex V uses the proton gradient generated by the electron transport chain to synthesize ATP from ADP and inorganic phosphate. When oligomycin is present, it disrupts the flow of protons back into the mitochondrial matrix, preventing the production of ATP and leading to cellular energy deficits.
Considering the complex nature of the electron transport chain and the role of inhibitors, these interactions are significant in understanding mitochondrial function, potential drug targets, and implications for conditions such as cyanide poisoning, wherein the pH of the intermembrane space would increase, as proton pumping is inhibited, leading to a decrease in ATP synthesis.