4.3 Enzyme inhibitors Flashcards
how does competitive inhibition work
a molecule/part of a molecule that is a similar shape to the substrate can fit into the active sit, this prevents the enzyme from catalysing and its inhibited this decreases rate of reaction most competitive enzymes can only bind temporarily
how do competitive inhibitors effect rates of reaction
they decrease rates of reaction for a given concentration of substrate but it doesnt change the maximum rate and if the substrate conc is high enough the maximum rate can still be reached
what are some examples of competitive inhibitors
statins are competitive inhibitors of an enzyme in the synthesis of cholesterol.
aspirin irreversibly inhibits the active site of COX enzymes (that produce pain and fever)
how do non competitive inhibitors work
an inhibitor will bind to the allosteric site (an alternate to the active site), altering the tertiary structure of the active site so the substrate no longer fits.
as the inhibitor does NOT compete with the substrate for the active site, it is non-competitive
what effects do non competitive inhibitors have on the rates of reaction
increasing concentration of enzyme or substrate will not change rate of reaction, but increasing the inhibitor concentration will decrease the rate of reaction further as more active sites become unavailable
what are some examples of irreversible non-competitive inhibitors
organophosphates used as insecticides and herbicides irreversibly inhibit the enzyme necessary for nerve impulse transmission.
proton pump inhibitors (PPIs) irreversibly block the enzyme system responsible for secreting hydrogen ions into the stomach (that causes long-term indigestion)
what is end-product inhibition
is the term used for enzyme inhibition that occurs when the product of a reaction acts as an inhibitor to the enzyme that produces it. this creates a negative feedback that means excess products are not made and resources are not wasted
