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20 Cards in this Set

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In the nomenclature of the cytochrome P450 the first number, first letter, and second number each mean what?
First number = Family name with 40% homology among each same family
First Letter = Subfamily name with 59% homology among each in the same subfamily
Second Number = Individual form within each family and subfamily
What does the CYP1A subfamily do?
metabolism of polycyclic hydrocarbons (anything with more than one aromatic ring)
It is induced by them as well.
What is carcinogenic about cigarette smoke?
The reactive intermediate of benzopyrene break down from CYP1A group.
Where is CYP1A1 found?
Extrahepatic Tissues (particularly the lung)
Smoking causes induction within the lungs
Where is CYP1A2 found?
Only in the liver
It is both constitutively expressed and inducible through smoking.
How does Dioxin work and what does it do?
It is an inducer of the CYP1A1 and CYP1A2 P450s. It binds to the Ah (aryl hydrocarbon hydrolase) receptor) which then translocates to the nucleus and binds the promotor region of the CYP1A gene (1A1 or 1A2)
What are the two types of polymorphisms of the Cytochrome P450 system?
Expression Polymorphism - Mutation in the promoter region which can cause a difference in responsiveness to treatment (may lead to a decreased risk of cancer by preventing production of carcinogenic metabolites)
Structural Polymorphisms - Mutation in the active site. Compound may not fit into the site or may not be able to catalyze the reaction as well.
Can what you eat influence a Cytochrome P450?
Yes dot dot dot
Remember Charcoal-Broiled Beef Diet! mmmmmmmm!!! I'm so damn hungry!
Which cytochrome P450 enzymes are responsible for the metabolism of Nicotine?
CYP2A6 and CYP2A13
What would a polymorphism of CYP2A6 or CYP2A13 do?
They would be less likely to become addicted to cigarette smoking due to the inability to rapidly metabolize nicotine. I think this also implies a decreased risk for developing cancer as well.
Of the CYP2B family of cytochromes which one is most important in humans and is it constitutive or inducible?
CYP2B6 and it is inducible
Of the CYP2C family what are the major forms in humans, what do they do, and how can they be tested?
There are 7 total in humans. Four listed are:
CYP2C8, CYP2C9, CYP2C18, CYP2C19
They metabolize about 30% of commonly used drugs such as Omeprazole and Diazepam
S-mephenytoin is a marker for CYP2C19 function
Flurbiprofen (analgesic) is a marker for CYP2C9 Function
They may be hormonally regulated
What does CYP2D6 do?
Metabolizes Codeine and Dexromethophan to morphine
It was the first P450 found to be polymorphic.
How can you test for CYP2D6 functionality?
Debrisoquine and dextromethophan
What is the common mutation seen in CYP2D6?
A gene duplication event that can produce up to 25 copies of the gene.
Due to the polypolymorphic characteristic of CYP2D6 it is a major target testing enzyme for drug makers because of population variability. Variability = Garbage!
What is CYP2E1 known for?
It is an uncoupled enzyme making superoxides and hydrogen peroxide (reactive oxygen intermediates)
What compounds can form reactive intermediates with CYP2E1?
Nitrosamine and Acetaminophen
What can induce CYP2E1 and what is a competitive inhibitor of CYP2E1?
Alcoholics and Alcohol
What other pathway metabolizes alcohol besides CYP2E1 and because of this what in vivo substate would be used to test the CYP2E1 system?
Alcohol dehydrogenase
Use Chlorzoxazone
What is the Major... when I say major I mean MAJOR P450 enzyme in humans, how much does it metabolize and what are its polymorphisms?
CYP3A4 and CYP3A5 are the major ones
They metabolize over 50% of commonly used drugs, but only the CYP3A5 seems to have polymorphisms yeilding elevated metabolic rates
Testing substrates include Erythromycin and Alfentanil