enzyme inhibitors Flashcards
describe how increasing the concentration of competitive inhibitors will affect the rate of the reaction
if the concentration of competitive inhibitors is increased, there will be a larger number of inhibitor molecules present compared to substrate molecules.
This increases the likelihood that more inhibitors will outcompete the substrate molecules for space and bind to the active site of enzymes.
This will block the active site , preventing substrates from binding,resulting in less ESC forming and more EIC
This causes the decrease of the rate of a reaction
how does a competitive inhibitor inhibit enzyme-controlled reactions
the competitive inhibitor bind to the active site of the enzyme by weeak hydrogen/ionic bonds as it has a similar shape to the substrate.
This blocks the active site and prevents the substrate from binding to the active site,starting a reaction
-the competitive inhibitor competes with the substrate for space in the active site of the enzyme
-enzyme cant carry out its function so said to have been inhibited
what are the two types of inhibitors
-competitive inhibitors
-non-competitive inhibitors
what is the definition of an inhibitor
its a molecule which binds to the enzyme, reducing its activity or even stopping it
by preventing the active site of the enzyme from binding to its specific substrate stimulating a reaction
do competitive inhibitors have irreversible effects
no they have reversible effects thus known as reversible inhibitors
Describe how increasing the concentration of a substrate will affect the rate of a reaction
( enzyme inhibited by a competitive inhibitor.)
the rate of the reaction will decrease following the inhibition of the enzyme.
However, the rate of the reaction increases with the increase in substrate concentration.
This is because the competitive inhibitor is a reversible inhibitor
the competitive inhibitor binds to the active site of the enzyme through weak hydrogen/ionic binding, meaning that they can be easily removed./
As well the increase in the concentration of substrates means that more substrates will have a higher chance of outcompeting the inhibitors for space in the enzymee
-when the concentration of inhibitor is high enough the substrate can knowch off the inhibitor and bind to the active site of an enzyme ,forming ESc and increasing the rate of thee reaction once again
what is Vmax
it is the fastest rate a reaction cn exceed to
how do the Vmax of an original reaction compare to one inhibited by a competitive inhibitor
they have same vmx initially the reactin inhibited has a lower Vmax but as the substrate concentration increases so does the V max of the reaction until it reaches the V max of the non inhibited reaction
describe how the rate of a reaction changes when first a competitive inhibitor is added and then later when the concentration of a substrate is increased
at first the rate of the reactin will decrease,this is because the competitive inhibitor will bind to the active site of enzymes,blocking the active site and preventing substrate molecules from binding to it,thus less ESC form so the rate of the reaction is decreased
However ,for competitive inhibitors as you increase the concentration of the substrate the rate of the reaction also increases
.This is because with larger number of substrate molecules the substrates have a greater chance of binding to the active sites of enzymes before inhibits
.Inhibitors can also be knocked off thee active site of enzymes as they are held only by weak hydrogen/ionic bonds so a substrate can remove them and bind to the active site .
More ESC will form and as a result the rate of the reaction will increase,eventually the rate will reach the normal rate of the reaction,
they will have the same Vmax,and the same amount of product will be produced if no inhibitor was present
state examples of competitive ,reversible inhibitors
statins
how does the vmax of a reaction inhibited by non-competitive inhibitors differ from original reaction
the v max of a reaction is lower is will remain lower ,it won’t reach the v max of the original reaction
what are statins used for
statins are used to decrease the blood cholesterol concentration which can lead to a heart disease
how do non-competitive inhibitors work
-non-competitive inhibitors bind to a site away from the active site of the enzyme known as the allosteric site. The allosteric site has a different shape than the active site of the enzyme
-the non-competitive inhibitor will bind to the allosteric site by forming strong covalent bonds and this will result in changes in the tertiary structure of the enzyme and so the shape of its active site
-the active site of the enzyme is no longer complementary to the substrate and the substrate can no longer bind so no reaction happen
-the enzyme has been permanently inhibited
give me an exception,a competitive inhibitor but with irreversible effects
aspirin,it prevents the synthesis of chemicals that produce fever and pain
Explain how the reaction rate changes when inhibited by non-competitive inhibitors and whether increasing substrate concentration influences the reaction rate
the reaction rate will decrease when the enzyme is inhibited by a non-competitive inhibitor.This is because as the inhibitor bind to thee allosteric site of the enzyme through covalent bonds the shape of the active site changes so the substrate can no longer binds and as a result no enzyme-substrate complex is formed so the rate of reaction increases
the increase of substrate concentration does not affect the rate of reaction.This is because the substrate cannot remove the inhibitor from the enzyme’s allosteric site as it’s joined to it by strong covalent bonds.Thus means that the effects on the inhibitor are irreversible and the enzyme is permanently inhibited.
what are non-competitive inhibitors also known as and why
irreversible inhibitors because they permanently inhibit an enzyme, have irreversible effects
is more or less a product formed ina reaction inhibited by a non-competitive inhibitor. Explain
less product as the enzyme is inhibited before its fully metabolised into its products
state example of a non-competitive inhibitor
-cyanide,binds to cytochrome oxidase preventing the production of ATP leading to death
describe all the differences between competitive and non-competitive inhibitors
-one binds to the active site of the enzyme,the other to the enzyme’s allosteric site
-one has a similar shape to the substrate the other doesn’t
-one forms weak hydrogen/ionic bonds with the enzyme the other strong covalent bonds
-one has a reversible effect the other has irreversible effects
-one can detach from the enzyme when the concentration of substrate increase the other cant,its always present
-only one permanently inhibits an enzyme
-for one increasing the concentration of the substrate increases the rate of reaction,for the other one it has no effect
-one allows the reaction it inhibits to eventually reach the same Vmax as the original reaction and produce the same amount of product whereas the other one makes the reaction it inhibits have a lower Vmax and produce less amount of product compared to the original reaction
describe similarities between both the competitive and non-competitive inhibitors
-in both the rate of reaction decreases in their presence
-both prevent the activity of the enzyme
-both used to control the amount of product produced
why does the end product inhibition need to be reversible
it needs to be reversible to regulate the metabolic pathway and control the amount of product produced so no resources are wasted
for example, when the level of a product falls the level of inhibition can also fall . This means that the enzyme will be able to function again and so more product can be made to increase the level of the protein
explain the process of end-of-product inhibition
In end-product inhibition,the end product of a metabolic pathway acts as an inhibitor, inhibiting an enzyme that functions earlier in the pathway.
explain how you will recognise a reaction inhibited by competitive and non-competitive inhibitors on a graph
the line that ends up touching the original line that hasn’t been inhibited is the competitive inhibitor as its effects are reversible and the V max of a reaction can reach the V max of the original reaction
the line that doesn’t touch the original and is much lower is the non-competititve inhibitor,it is always present so enzyme is permanently inhibited and the V max of a reaction will be lower as result
what happens when the product levels decrease in an end-product inhibition process
inhibition will also fall
the end-product will detach from the allosteric site of the enzyme, causing the active site to reform its shape so that it is once again complementary to the substrate and the specific substrate can bind to it resulting in ESCs.
The enzyme is functioning again and is catalysing the reaction earlier on it the pathway
