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⚗️biological chemistry ii review

IMP dehydrogenase

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

IMP dehydrogenase is an enzyme that catalyzes the conversion of inosine monophosphate (IMP) to xanthosine monophosphate (XMP) in the purine biosynthesis pathway. This reaction is a crucial step in the de novo synthesis of purine nucleotides, linking the production of AMP and GMP, which are essential for DNA and RNA synthesis.

5 Must Know Facts For Your Next Test

  1. IMP dehydrogenase is the rate-limiting enzyme in the de novo synthesis pathway for GMP, making it a key regulatory point in purine metabolism.
  2. The enzyme requires NAD+ as a cofactor for its activity, facilitating the oxidation of IMP to XMP.
  3. Inhibition of IMP dehydrogenase can be a therapeutic target for certain cancers and autoimmune diseases due to its role in regulating lymphocyte proliferation.
  4. The activity of IMP dehydrogenase can be influenced by various allosteric regulators and feedback mechanisms related to nucleotide levels.
  5. Genetic mutations in the IMP dehydrogenase gene can lead to severe immunodeficiency disorders due to impaired purine synthesis.

Review Questions

  • How does the function of IMP dehydrogenase fit into the larger picture of purine metabolism?
    • IMP dehydrogenase plays a central role in purine metabolism by catalyzing the conversion of IMP to XMP, which is necessary for producing GMP. This step is crucial because it helps balance the synthesis of adenine and guanine nucleotides, ensuring that both are available for DNA and RNA synthesis. Additionally, the regulation of this enzyme affects overall cellular energy and nucleotide pools, impacting cell proliferation and function.
  • Discuss the significance of IMP dehydrogenase as a therapeutic target in treating certain diseases.
    • IMP dehydrogenase has gained attention as a therapeutic target due to its critical role in regulating purine synthesis. Inhibiting this enzyme can slow down the proliferation of lymphocytes, making it a potential strategy for treating cancers and autoimmune diseases where cell growth is unregulated. Drugs like mycophenolate mofetil work by inhibiting IMP dehydrogenase to suppress immune responses, showcasing its importance in pharmacology.
  • Evaluate how variations in IMP dehydrogenase activity could affect cellular functions and what implications this might have for human health.
    • Variations in IMP dehydrogenase activity can significantly impact cellular functions, particularly those related to nucleotide synthesis and cell proliferation. Reduced enzyme activity can lead to an imbalance in purine levels, resulting in impaired DNA and RNA synthesis, which may cause issues such as immunodeficiency or increased susceptibility to infections. Conversely, overactivity may contribute to uncontrolled cell growth seen in certain cancers. Understanding these variations opens up pathways for targeted therapies that can address specific health conditions linked to purine metabolism.