W14/L6: *Parslow CYP Flashcards
(8 cards)
1
Q
How do dietary toxins get to the liver?
A
Directly, via the hepatic portal vein
2
Q
Which molecules are oxidised by P450 system?
A
ALL foreign chemicals with MW < 5,000
3
Q
Where in the cell are the P450 cytochromes located?
A
Endoplasmic reticulum
Mitochondria
4
Q
What are microsomes?
A
Pink spherical vesicles with embedded cytochrome P450. They don’t exist in cells - they’re an artefact of centrifuging.
5
Q
What sort of enzymes are the P450s?
A
Monoxygenases
6
Q
What reaction do the P450s typically catalyse?
A
RH + NADPH + H+ + O2 —>
ROH + H2O + NADP+
(The key point is that RH becomes ROH)
7
Q
What initiates the P450 cycle of reactions?
A
Binding of a substrate to the P450
8
Q
What P450 is deficient in people who can’t convert codeine to morphine?
A
CYP 2D6
