Cytochrome c oxidase

Definition

Cytochrome c oxidase is a critical enzyme in the electron transport chain that catalyzes the final step of cellular respiration, transferring electrons from cytochrome c to molecular oxygen and facilitating the production of water. This enzyme is essential for oxidative phosphorylation, as it helps establish a proton gradient across the inner mitochondrial membrane, ultimately leading to ATP synthesis through chemiosmosis.

5 Must Know Facts For Your Next Test

1. Cytochrome c oxidase is composed of multiple subunits and contains metal ions such as copper and iron, which are crucial for its electron transfer capabilities.
2. The enzyme directly contributes to the creation of a proton gradient by pumping protons from the mitochondrial matrix into the intermembrane space, which is vital for ATP production.
3. Mutations in the genes coding for cytochrome c oxidase can lead to severe mitochondrial diseases, highlighting its importance in energy metabolism.
4. Cytochrome c oxidase plays a role in regulating apoptosis (programmed cell death) by releasing cytochrome c when cells undergo stress.
5. This enzyme is also a target for certain poisons, such as cyanide, which inhibits its function, thereby halting cellular respiration and ATP production.

Review Questions

• How does cytochrome c oxidase contribute to the overall function of the electron transport chain?
  • Cytochrome c oxidase serves as the terminal component of the electron transport chain, where it accepts electrons from cytochrome c and transfers them to molecular oxygen. This reaction not only produces water but also facilitates the pumping of protons into the intermembrane space. By contributing to the proton gradient, it plays a crucial role in driving ATP synthesis via ATP synthase, making it integral to cellular energy production.
• Discuss how dysfunctions in cytochrome c oxidase can affect cellular metabolism and health.
  • Dysfunctions in cytochrome c oxidase can severely impair cellular respiration and energy production. Such impairments can lead to a decrease in ATP levels, affecting all energy-dependent processes in cells. Moreover, mutations in its coding genes have been associated with various mitochondrial diseases, which can manifest as muscle weakness, neurological disorders, and other serious health issues due to inadequate energy supply.
• Evaluate the implications of cytochrome c oxidase inhibition by toxins like cyanide on cellular respiration and organismal survival.
  • Inhibition of cytochrome c oxidase by toxins such as cyanide effectively shuts down cellular respiration by preventing electron transfer to oxygen. This halts ATP production rapidly, leading to cellular energy failure. The rapid depletion of ATP can result in organ failure and death if not treated promptly. Understanding this mechanism emphasizes the critical role of cytochrome c oxidase in maintaining cellular function and highlights vulnerabilities in metabolic processes that can be exploited by toxins.

Related terms

Electron transport chain: A series of protein complexes located in the inner mitochondrial membrane that facilitate the transfer of electrons from electron donors to electron acceptors, generating a proton gradient.

ATP synthase: An enzyme that uses the proton gradient created by the electron transport chain to synthesize ATP from ADP and inorganic phosphate during oxidative phosphorylation.

Oxidative phosphorylation: The process by which ATP is formed as a result of the transfer of electrons from NADH and FADH2 to oxygen through the electron transport chain, coupled with the establishment of a proton gradient.