Enzyme Inhibition
{
Why enzymes don’t work

An enzyme is just
a folded protein
Remember!!!
Organic catalysts-speed up
the rate of the reaction
 Proteins
 have –ase after their name

Enzymes are…
Enzymes
Enzymes fit together with
substrates to aid a chemical
reaction
 Lock and Key vs Induced Fit

Video on my website that you
need to watch and take notes
Due by Friday!

Enzymes

There are several things that
can effect the rate at which an
enzyme works: temperature,
pH, enzyme concentration,
substrate concentration, and
the presence of inhibitors or
activators.
Things effecting the rate at
which and enzyme works

When and enzyme stops
working in its normal manner.
This could be due to a variety
of inhibitors including:
nonspecific, competitive, and
noncompetitive.
What is enzyme inhibition?
Non-specific: Any physical or
chemical change that
ultimately denatures any
enzyme – irreversible
 Denature – when the enzyme
loses its folded shape; it
basically falls apart because
bonds have been broken

Non-specific vs Specific

Temperature – normally if you
increase a temperature you
speed up a reaction. However
if you increase the temperature
too much and it is no longer in
the enzymes optimum range it
will cause it to denature.
Things that can cause an
enzyme to denature
Example of a protein that
has denatured due to
increased temperature

pH – an increase or decrease
of pH out of the enzymes
optimum range can cause
denaturation.
Things that can cause an
enzyme to denature
Specific inhibition – only
works on specific enzymes, not
all of them
 Competitive and noncompetitive inhibition

Non-specific vs specific
Competitive vs non-competitive
An inhibitor
competes with
the substrate for
the active site
 Like a race
 Normally
reversible if
other substrates
are available for
the inhibitor to
bind with

Competitive Inhibition
An inhibitor binds to the
enzyme at a site different
than the active site.
 This special site that is just
for the inhibitor is called
the allosteric site

Non-competitive Inhibition

The binding of the inhibitor to
the allosteric site normally
changes the conformation of
the active site so the substrate
and enzyme can’t bind
Non-competitive Inhibition
Normally this type of
inhibition is not permanent.
 However this is not true in all
cases, sometimes it is
irreversible and the enzyme
can no longer work.

Non-competitive Inhibition

Cofactors are non-protein inorganic
chemical compounds bound to a
protein


Helps the protein function during
biochemical reactions and increase
the rate at which the enzyme works
Coenzymes are organic molecules
(usually vitamin or mineral) that
are required by certain enzymes to
carry out reactions
Cofactors and Coenzymes