A-LevelBiologyEnzymes9700/12 · Oct/Nov 2016 · Q151 Mark
Substances called furanocoumarins are found in some fruits, where they act as inhibitors of the enzyme CYP3A4. This enzyme is needed to break down toxins in the human digestive system, so dangerous levels of these toxins may develop if these fruits are eaten. What does this information suggest about molecules of the enzyme CYP3A4?
AThey lower the activation energy of the toxin breakdown process.
BThey show specificity for a particular substrate found in fruits.
CThey will change permanently when acted upon by furanocoumarin molecules.
DThey will resume normal activity when levels of furanocoumarins decrease.
✓ Correct answer
A: They lower the activation energy of the toxin breakdown process.
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