Lecture 11 - Enzyme inhibition Flashcards
Many, but not all, enzyme inhibitors structurally resemble
the substrate
Types of enzyme inhibitors
- Competitive
- Uncompetitive
- Noncompetitive
- Mixed
In competitive inhibition, there is a decrease in enzymatic activity caused by
binding of a substrate analogue to the active (catalytic) site
In competitive inhibition, the inhibitor competes with the ______ for the ______ on the enzyme
substrate; active site
In competitive inhibition, Vmax is
unchanged
In competitive inhibition, Km
increases
Increasing substrate concentration can
overcome competitive inhibition
Using the Lineweaver-Burk plot, in competitive inhibition, the y-intercept
does not change
The Lineweaver-Burk plot contains parallel lines in
uncompetitive inhibition
In uncompetitive inhibition, Vmax
decreases
In uncompetitive inhibition, Km
decreases
An uncompetitive inhibitor effects the ______ of the enzyme, but not the ______.
catalytic function; substrate binding
Using the Lineweaver-Burk plot, in uncompetitive inhibition, the y-intercept
decreases
Using the Lineweaver-Burk plot, in uncompetitive inhibition, the slope
stays the same
In noncompetitive inhibition, the inhibitor binds to
a site other than the active site and distorts the active site to inhibit the reaction
In noncompetitive inhibition, the inhibitor does not
interfere with substrate binding
In noncompetitive inhibition, the value of Vmax
decreases
In noncompetitive inhibition, the value of Km
remains constant
Using the Lineweaver-Burk plot, in noncompetitive inhibition, the y-intercept
changes
Using the Lineweaver-Burk plot, in noncompetitive inhibition, the slope
changes
Using the Lineweaver-Burk plot, in noncompetitive inhibition, the x-intercept
stays the same
In mixed inhibition, the inhibitor binds to
a site other than the active site, and distorts the active site to inhibit the reaction
In mixed inhibition, the two Ki values are
not equal
In noncompetitive inhibition, the two Ki values are
equal
Using the Lineweaver-Burk plot, in mixed inhibition, the y-intercept
changes
Using the Lineweaver-Burk plot, in mixed inhibition, the slope
changes
What causes permanent inactivation in irreversible inhibition
covalent binding of an inhibitor to an enzyme
Suicide substrates are molecules used to
bind to an enzyme irreversibly and inactivate it
An example of a suicide inhibitor is
penicillin
