NADH dehydrogenase

Definition

NADH dehydrogenase, also known as Complex I, is a large enzyme complex that is the first and largest of the five complexes in the electron transport chain of cellular respiration. It is responsible for the oxidation of NADH, transferring electrons to the next complex in the chain and contributing to the proton gradient that drives ATP synthesis.

5 Must Know Facts For Your Next Test

1. NADH dehydrogenase is the largest and most complex of the five enzyme complexes in the electron transport chain, containing over 40 different subunits.
2. It catalyzes the oxidation of NADH, transferring two electrons to the next complex (Coenzyme Q) and simultaneously translocating four protons across the inner mitochondrial membrane.
3. The transfer of electrons through NADH dehydrogenase is coupled to the pumping of protons, contributing to the proton gradient that drives ATP synthesis.
4. Defects in NADH dehydrogenase can lead to mitochondrial disorders, as it is a critical component of cellular respiration and energy production.
5. NADH dehydrogenase is also known as Complex I because it is the first complex in the electron transport chain, accepting electrons from NADH and passing them on to Coenzyme Q.

Review Questions

• Explain the role of NADH dehydrogenase in the electron transport chain and its importance in cellular respiration.
  • NADH dehydrogenase, or Complex I, is the first and largest enzyme complex in the electron transport chain of cellular respiration. It is responsible for oxidizing NADH, a key electron carrier produced during earlier stages of metabolism, and transferring the electrons to the next complex in the chain. This electron transfer is coupled to the translocation of protons across the inner mitochondrial membrane, contributing to the proton gradient that ultimately drives the synthesis of ATP through oxidative phosphorylation. NADH dehydrogenase is a critical component of the energy-producing machinery of the cell, and defects in this complex can lead to mitochondrial disorders and impaired cellular function.
• Describe the structural complexity of NADH dehydrogenase and how its unique features contribute to its function.
  • NADH dehydrogenase is the largest and most complex of the five enzyme complexes in the electron transport chain, containing over 40 different subunits. This structural complexity allows NADH dehydrogenase to perform its crucial role in cellular respiration. The multiple subunits facilitate the oxidation of NADH, the transfer of electrons to Coenzyme Q, and the simultaneous translocation of protons across the inner mitochondrial membrane. The intricate arrangement of these subunits, along with the presence of various cofactors and prosthetic groups, enables NADH dehydrogenase to efficiently couple electron transport with proton pumping, generating the proton gradient that drives ATP synthesis through oxidative phosphorylation.
• Analyze the importance of NADH dehydrogenase in maintaining overall cellular function and energy production, and discuss the potential consequences of its dysfunction.
  • NADH dehydrogenase is a critical component of the electron transport chain and oxidative phosphorylation, which are the primary means of ATP generation in eukaryotic cells. By oxidizing NADH and transferring electrons to the next complex in the chain, NADH dehydrogenase plays a central role in the process of cellular respiration and energy production. The coupling of this electron transfer to proton translocation across the inner mitochondrial membrane is essential for establishing the proton gradient that drives the synthesis of ATP, the universal energy currency of the cell. Disruptions or defects in NADH dehydrogenase can therefore have severe consequences, leading to mitochondrial disorders and impaired cellular function due to the reduced capacity for energy production. This highlights the vital importance of NADH dehydrogenase in maintaining overall cellular homeostasis and the need for its proper functioning to support the energy demands of various tissues and organs throughout the body.

Related terms

Electron Transport Chain: The series of protein complexes in the inner mitochondrial membrane that facilitate the transfer of electrons from one complex to the next, ultimately reducing oxygen and generating a proton gradient used for ATP synthesis.

Oxidative Phosphorylation: The metabolic pathway in which cells use enzymes to oxidize nutrients, transferring electrons through a series of complexes (the electron transport chain) to ultimately reduce oxygen and generate a proton gradient that drives ATP synthesis.

Proton Gradient: The uneven distribution of protons (H+ ions) across a membrane, creating a potential energy difference that can be used to drive the synthesis of ATP.