Enzyme Inhibition

how can enzymes be inhibited

the binding of specific small molecules and ions.

exampls of drugs which inhibit enzymes

fluxoteine
atorvastatin
methotrexate

what enzymes does fluoxetine inhibit
-what is its purpose

pre-synaptic serotonin receptors
-anti-depressant

what does atorvastatin inhibit
-purpose

HMG Co-A reductase

-reduce cholesterol

what does methotrexate inhibit
-puropse

dihydrofolate reductase

-oncology

how does methotrexate work and what is it

Methotrexate is a structural analog of dihydrofolate, a substrate for dihydrofolate reductase

what binding occurs with methotrexate

What makes it such a potent competitive inhibitor is that it binds to the enzyme 1 000 times as tightly as the natural substrate binds, and it inhibits nucleotide base synthesis.

what are the 3 common methods of enzyme inhibition

-competitive
-uncompetitive
non-competitive

what is competitive inhibition

The competitive inhibitor often resembles the substrate and binds to the active site of the enzyme

. The substrate is thereby prevented from binding to the same active site.

how does a competeitve inhibitor reduce the rate of catalysis

by reducing the proportion of enzyme molecules bound to a substrate.

can competitve inhibition be overcome
-if so how

competitive inhibition can be relieved by increasing the substrate concentration.

Under these conditions, the substrate successfully competes with the inhibitor for the active site.

example of a competeive inhibitor

methotrexate

what is uncompetitve inhibition

the inhibitor binds only to the enzyme-substrate complex.

how is the binding site of an uncompetitive inhibitor created

he binding site of an uncompetitive inhibitor is created only on interaction of the enzyme and substrate

can uncompetitive inhibition be overcome by increasing substrate

no

what is non-competitve inhibition

the inhibitor and substrate can bind simultaneously to an enzyme molecule at different binding sites

what can a non-competition inhibitor lead to

free enzyme or the enzyme-substrate complex.

how does a non-competitve inhibitor act

A noncompetitive inhibitor acts by decreasing the concentration of functional enzyme rather than by diminishing the proportion of enzyme molecules that are bound to substrate.

can a non-competitve inhibitor be overcome by increaing the concentration of substrate

NO

what is the dissocation constant of an inhibitor

in competitve inhibition is Vmax affected

NO
-vmax will always be reached with an increase in substrate concentration

does Km increase in the presence of an inhibitor

yes
-its called Km app

graph of competeive inhibition

what happens when the reciprocal of the competitve inhibition is taken

the lines converge at the same spot

does the Vmax change in uncompeteitve inhibition

yes
-it lowers

graph of uncompetitve inhibition