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2009-11-23 13:50:43
special functions of the Liver

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  1. acetaminophen catabolized by CYP2E1 yields
    NAPQI ( N acetyl-p-benzoquinoneimine)
  2. what happends if large amount of acetaminophen is digested? how?
    can be toxic. normally, NAPQI is toxic. However, certain amount of NAPQI is okay because it will be conjugated with glutathione by glutathione s transferase. But when there is overload of NAPQI due to overdose of acetaminophen, the body will run out of glutathione. Then NAPQI can damage cells.
  3. enzyme that produces NAPQI from acetaminophen

    this enzyme is induced by

    induced by alcohol
  4. explain acetaminophen metabolism in alcoholics
    they have higher sensitivity to acetaminophen. they produce more CYP2E1 and build up more NAPQI
  5. antidote for acetaminophen
  6. what happends to majority of acetaminophen ingested
    95% acetaminophen will be glucuronylated or sulfated. yielding acetaminphen glucuronate or acetaminophen sulfate.

    5% digested by CYP2E1
  7. T or F: CYP2E1 is a cytochrome P450
  8. increase transcription of cytochrome P450 by activating xenobiotic receptors
  9. this cytochrome p450 metabolizes 50% of all therpeutic drugs
  10. what happens to drug when CYT P450 is iduced?
    drug concentration decreases (more metabolized)
  11. what food inhibits CYP3A4
    grapefruit juice
  12. predominant form of aflatoxin
    aflatoxin B1 ( also most toxic aflatoxin)
  13. two cytochromes that metabolizes aflatoxin B1
    CYP1A2, CYP3A4, these activates aflatoxin B1 to 2,3 epoxide
  14. DNA mutation caused by epoxide
    G->T transversion. this inactivates p53 leading to hepatic carcinoma
  15. T or F- most mutagens and carcinogens require activation
    True ( has to be metabolized to active form)
  16. drugs that increase the synthesis of CYT P450
    phenobarbital, rifampin, carbamazepine
  17. How many pseudogenes are there in CYP
    58 pseudogenes
  18. flavoprotein reductase in the mitochondria
    NADPH ferredoxin reductase
  19. flavoprotein in the ER
    NADPH cytochrome P450 reductase
  20. accepts two electrons required for the monooxygenease reaction
    NADPH dependent flavoprotein reductase
  21. state of heme iron required for monooxygenation
    ferrous state ( heme iron has to be reduced from ferric to ferrous)
  22. terminal e- acceptor in the mammalian cells
    cytochrome P450