Enzyme inhibitors 2.4.8 Flashcards
What is an inhibitor?
Substances that reduce the activity of an enzyme, by inhibiting the formation of ES complexes and therefore product formation.
What is a competitive inhibitor?
They have a similar shape to a substrate molecule and compete directly with the substrate for the enzymes active site. (They block the active site).
How does a competitive inhibitor reduce rate of reaction?
They reduce the number of free active sites for the substrate molecules to bind to
What is the molecule known as when an inhibitor and active site bind together?
Enzyme-inhibitor complex, which is catalytically inactive.
What does the amount of inhibition depend on?
The relative concentration, as if the concentration of competitive inhibitors is higher then the collision rate between those and the active sites increase- and so the effect of inhibition is greater.
What is an inactivator?
When a competitive inhibitor binds irreversibly to the enzymes active site.
What is a non-competitive inhibitor?
A molecule that binds to the enzyme somewhere other than the active site
What is an allosteric site?
A site away from the active site
How do non-competitive inhibitors work?
They bind to the allosteric site which disrupts the tertiary structure (reversible or irreversible), changing the shape of the active site - so ES complexes can no longer be formed.
What happens to rate of reaction during inhibition?
The Vmax is reduced due to the greater degree of inhibition.
What can help the reduced rate of reaction return to its Vmax during inhibition?
Adding more substrate
What is end-product inhibition?
After the catalysed reaction is complete, product molecules may remain bound to the enzyme which prevents the enzyme making more product than the cell requires.
When may the inhibitor detach from the enzyme?
When the concentration of the product decreases, so it detaches to allow the metabolic pathway to run again.
How do metabolic poisons affect enzyme rate of reaction?
They inhibit/inactivate enzymes by exerting their effect.
Give an example of a metabolic poison
Cyanide, as it inhibits aerobic respiration and the action of catalase
