1.9- ENZYME INHIBITION Flashcards
What are enzyme inhibitors?
substances that directly or indirectly interfere with functioning of active site of enzyme
What do enzyme inhibitors do?
reduce enzyme activity
What are two types of enzyme inhibitors?
competitive inhibitors
non-competitive inhibitors
What do competitive inhibitors do?
bind to active site of enzyme
What do non-competitive inhibitors do?
bind to enzyme at position other than active site
What shape do competitive inhibitors have?
molecular shape similar to that of the substrate
What does competitive inhibitors having a similar shape to the substrate allow them to do?
allow them to occupy the active site of an enzyme
Why do competitive inhibitors compete with the substrate?
as they can occupy the active site so compete for with substrate for available active sites
What determines the effect of the inhibitors on the enzyme activity?
difference between concentration of inhibitor and concentration of substrate
What happens when if the substrate concentration is increased?
effect of the inhibitor is reduced
Is the competitive inhibitor permanently bound to the active site?
no
What happens when the competitive inhibitor leaves?
another molecule can take its place
What could be the molecule that takes the place of the competitive inhibitor once it leaves?
a substrate or inhibitor molecule, depending on how much of each type is present
sooner or later what will happen?
all the substrate molecules will occupy an active site
What will make it longer for all the substrate molecules to occupy an active site?
greater the concentration of inhibitor
What enzyme and substrate does an example of a competitive inhibitor occur with?
a respiratory enzyme that acts on succinate
What is another compound that can inhibit the respiratory enzyme?
malonate
How can malonate inhibit the respiratory enzyme?
has a very similar molecular shape to succinate
As the malonate has a very similar molecular shape to the succinate what is it able to do?
easily combines with the enzyme and blocks succinate from combining with the enzyme’s active site
What is another example of an inhibitor and of what enzyme?
inhibition of enzyme transpeptidase by penicillin
What do non-competitive inhibtors do?
attach themselves to the enzyme at binding site which is not the active site
Upon attaching to the enzyme, what does the non-competitive do?
alters shape of enzyme
What happens as the shape of the enzyme is altered due to the non-competitive inhibitor?
active site of shape changes
What happens as the shape of the active site is changed?
substrate molecule can no longer occupy active site so enzyme cannot function
Why does increasing the substrate concentration not decrease the effect of the inhibitor ?
substrate and inhibitor not competing for same site
