Learning Goal Describe competitive and noncompetitive inhibition and reversible and irreversible inhibition Inhibitors Inhibitors are molecules that cause a loss of catalytic activity ID: 936008
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Slide1
20.5 Enzyme Inhibition
The structure of a noncompetitive inhibitor does not resemble the substrate and does not compete for the active site.
Learning Goal Describe competitive and noncompetitive inhibition and reversible and irreversible inhibition.
Slide2Inhibitors
Inhibitorsare molecules that cause a loss of catalytic activity.prevent substrates from fitting into the active sites.
can be classified as either reversible inhibitors or irreversible inhibitors.
Slide3Reversible Inhibition
Reversible inhibitorscause a loss of enzyme activity that can be restored.can act in different ways but do not form covalent bonds with the enzyme.
Reversible inhibition can be competitive or noncompetitive.Competitive inhibitors compete for the active site.Noncompetitive inhibitors act on another site that is not the active site.
Slide4Competitive Inhibitors
A competitive inhibitor
has a chemical structure and polarity similar to the substrate.competes with the substrate for the active site.has its effect reversed by increasing substrate concentration.
Slide5Some bacterial infections are treated with competitive inhibitors called antimetabolites
. Sulfanilamide competes with
p-aminobenzoic acid (PABA), an essential metabolite in the growth cycle of bacteria.Antimetabolites: Competitive Inhibitors in Medicine
Slide6Noncompetitive Inhibitors
A noncompetitive inhibitor
has a structure that is much different from that of the substrate.does not compete for the active site.distorts the shape of the enzyme, which prevents the binding of the substrate at the active site.cannot have its effect reversed by adding more substrate.
Slide7Irreversible Inhibition
In irreversible inhibition, enzyme activity is destroyed when the inhibitor covalently bonds with R groups of an amino acid that may be near the active site.
the inhibitor changes the shape of the enzyme, which prevents the substrate from entering the active site.
Slide8Irreversible Enzyme Inhibitors
Slide9Enzyme Inhibition Summary
Slide10Study Check
Identify each description of an inhibitor that is either competitive or noncompetitive.
Increasing substrate reverses inhibition.It binds to the enzyme’s surface
but
not to the active site.
Its
structure is similar to that of
the
substrate.
Inhibition
is not reversed by adding
more
substrate.
Slide11Solution
Identify each description of an inhibitor that is either competitive or noncompetitive.
Increasing substrate reverses inhibition. competitive It binds to the enzyme’s surface
but
not
to
the active site.
noncompetitive
Its
structure is similar to that of
the
substrate.
competitive
Inhibition
is not reversed by adding
more
substrate.
noncompetitive