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Mitochondrial Function and Oxidative Phosphorylation

• Electron Transport Chain (ETC) Components and Oxidized States:

  • In a specific experimental setup with malate and cyanide, Complex I and CoQ remain oxidized after 7 minutes according to the described setup.
  • Complex II, Complex III and Cytochrome C won't be in oxidized state after being exposed to cyanide in a 7-minute incubation with malate as the substrate in a mitochondria sample.

• Proton Motive Force and Valinomycin:

  • Valinomycin, a drug that allows potassium ions to cross the inner mitochondrial membrane, reduces proton motive force (PMF).
  • The PMF decreases, disrupting the electrochemical gradient across the membrane.

• Dinitrophenol (DNP) and Oxidative Phosphorylation Uncoupling:

  • DNP uncouples oxidative phosphorylation by allowing proton exchange across the inner mitochondrial membrane.
  • This process disrupts the proton gradient needed for ATP generation, leading to less ATP synthesis.

Anemia and Iron Deficiency

• Iron Deficiency Anemia and Electron Transport:

  • Iron deficiency impairs electron transport chain function due to critical roles of Fe-S centers in electron transfer.

• Iron and TCA Cycle Enzymes:

  • Iron acts as a cofactor for α-ketoglutarate dehydrogenase in the TCA cycle.
  • This reaction supports electron flow through the ETC.

OXPHOS Diseases

• OXPHOS Diseases and Mitochondrial Function:
  • Patients with OXPHOS diseases typically display a high NADH/NAD+ ratio in mitochondria.
  • There is a defect in the integrity of the inner mitochondrial membrane.
  • A high ATP:ADP ratio within the mitochondria isn't typical in OXPHOS diseases.

Lead Poisoning and Heme Synthesis

• Lead Poisoning and Heme Synthesis:
  • Lead exposure disrupts heme synthesis.
  • This particularly affects proteins or complexes that depend on heme, such as hemoglobin, and myoglobin but not Complex I, III or IV.

Rotenone and ATP Production

• Rotenone Inhibition and ATP Production:
  • Rotenone inhibits NADH dehydrogenase, drastically decreasing ATP production in heart mitochondria.
  • The inhibition impacts the electron flow causing substantial losses in ATP production.

Oxidative Phosphorylation

• Key Components of Oxidative Phosphorylation:

  • Oxidative phosphorylation relies on using NADH and FADH2 to accept electrons when they are oxidized.
  • It necessitates the presence of ATP synthase for ATP synthesis and a source of electrons (usually oxygen).

• Mitochondrial Membrane Disruption:

  • Disrupting non-covalent interactions at the membrane surface through high-salt solutions minimizes oxygen consumption due to loss of ETC components.
  • This loss can affect various components of the ETC.

Uncoupling Protein (UCP) and Weight Loss

• Uncoupling Proteins and Weight Loss Drugs:
  • Activation of UCPs could increase body temperature as a side effect of weight-loss drugs.
  • This might lead to decreased oxidation of acetyl CoA and decreased glycolysis.

Free Radical Damage and Antioxidants

• Free Radical Damage and Antioxidants:

  • β-carotene, glutathione peroxidase, superoxide dismutase (SOD), vitamin C, and vitamin E are antioxidants.

• Superoxide Dismutase (SOD) Reaction:

  • SOD catalyzes the conversion of superoxide radicals to hydrogen peroxide and oxygen.
  • The reaction involves the utilization of superoxide and hydrogen ions for this process.

• Vitamin E Mechanism:

  • Vitamin E functions as an antioxidant by participating in the reduction of free radicals.

• Hydrogen Peroxide Conversion:

  • Iron catalyzes the conversion of hydrogen peroxide into harmful radicals.

• Mitochondrial DNA and Oxidative Damage:

  • Mitochondrial DNA has a higher susceptibility to oxidative damage than nuclear DNA due to the permeability of the mitochondrial membrane to ROS and the lack of histones.

Chronic Granulomatous Disease (CGD)

• Chronic Granulomatous Disease and Immune System Defects:
  • CGD is connected to an inability to generate hypochlorous acid (HOCl) — a vital component of the immune system's response to pathogens.

Amyotrophic Lateral Sclerosis (ALS)

• ALS and Oxidative Stress:
  • A genetic predisposition to ALS can involve an inability to detoxify hydrogen peroxide.

Nitric Oxide (NO) and Diseases

• Nitric Oxide (NO) and High Concentrations:
  • High concentrations of nitric oxide (NO) can lead to the formation of reactive nitrogen species (RNS) associated with various diseases.

Xenobiotics and Free Radical Injury

• Xenobiotics and Free Radical Formation:
  • Exposure to xenobiotics, such as alcohol or medications, can elevate free radical injury via the induction of cytochrome P450-containing enzymes.

Antioxidant Foods

• Foods High in Antioxidants:
  • Citrus fruits and green leafy vegetables contain high levels of antioxidants.