Enzyme Inhibition - 1.9 Flashcards
What are enzyme inhibitors?
Substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduce its activity.
What are the two type of enzyme inhibitors?
- Competitive inhibitors - which bind to the active site of the enzyme.
- Non-competitive inhibitors - which bind to enzyme at a position other than the active site.
What is the shape of competitive inhibitors and what does this allow?
Competitive inhibitors have a molecular shape similar to that of the substrate. This allows them to occupy the active site of an enzyme. They therefore compete with the substrate for the available active sites.
What determine the effect of competitive inhibitors on enzyme action?
It is the difference between the concentration of the inhibitor and the concentration of the substrate that determines the effect that this has on enzyme activity. If the substrate concentration is increased, the effect of the inhibitor is reduced.
Is the effect of competitive inhibitors permanent?
The inhibitor is not permanently bound to the active site and so, when it leaves, another molecule can take its place, be it a substrate or inhibitor; the greater the concentration of competitive inhibitor, the longer it will take for a substrate to bind with active site.
What is an example of a competitive inhibition?
Succinate is an important respiratory enzyme. Another compound, called malonate, can inhibit the enzyme because it has a very similar molecular shape to succinate.
What do non-competitive inhibitors do?
Attach themselves to th e enzyme at a binding site which is not the active site. Upon attaching to the enzyme, the inhibitor alters the shape of the enzyme and thus its active site in such a way that substrate molecules can no longer occupy it, so the enzyme cannot function.
Are non-competitive inhibitors permanent?
Many non-competitive inhibitors are irreversible and permanent, and effectively denature the enzyme which they inhibit.
What is a metabolic pathway?
A series of reactions in which each stems catalysed by an enzyme.
How do enzymes relate to metabolic pathways?
The enzymes that control pathways are often attached to the membrane of a cell organelle in a very precise sequence. To keep a steady concentration of a particular chemical in a cell, the same chemical often acts as am inhibitor of an enzyme at the start of a reaction.
What is end product inhibition?
End product inhibition is negative feedback used to regulate the production of a given molecule. This type of inhibition is usually non-competitive.
