Reversible Enzyme Inhibition Flashcards
In this type of inhibition, the inhibitor competes with the substrate for the active site of the enzyme
competitive
True or false? a competitive inhibitor usually has some structural similarity to the substrate
true
What does a competitive inhibitor bind to?
free enzyme
Competitive inhibition increases the “apparent” ___ of the enzyme
Km
The following describes what type of inhibition? By removing some of the free enzyme from the reaction, it appears to take a higher [S] to achieve 1/2 Vmax
competitive
What does competitive inhibition look like on lineweaver - burk plot?
X intercept is different but lines go through Y intercept at same point
In competitive inhibition, Vmax is unaffected. Explain why.
since by increasing [S], the inhibition can be overcome and Vmax can be achieved
___ are competitive inhibitors of the rate limiting enzyme of cholesterol biosynthesis
statins
The following version of the michaelis-menten equation describes what type of inhibition:
v = Vm[S] / Km(1+[I]/Ki)+[S]
competitive
note: only Vm[S] is on top
A noncompetitive inhibitor binds to either ___ or ___
E; ES
Do noncompetitive inhibitors bind to the active site?
no, therefore don’t compete with substrate binding
Since a noncompetitive inhibitor doesn’t compete with the S, increasing [S] will have what effect?
none, won’t overcome the inhibition
A noncompetitive inhibitor decreases the “apparent” ___ of the enzyme
Vmax
The effect of a ____ inhibitor is to effectively reduce the number of active enzyme molecules, which has the appearance of reducing [Etotal]
noncompetitive
What does noncompetitive inhibition look like on a lineweaver-burk plot?
X intercepts are the same but lines cross at different points on Y intercept
The following version of the michaelis-menten equation describes what type of inhibition:
v = Vm[S]/(1+[I]/Ki)//Km+[S]
noncompetitive
note: only Km + [S] on bottom
Many heavy metals such as Hg and Pb interact with the -SH groups on enzymes and act via ____ inhibition
noncompetitive
An uncompetitive inhibitor binds only to the ___ of an enzyme
ES
In uncompetitive inhibition, it is proposed that substrate binding alters the enzyme structure such that…
the inhibitor may subsequently bind
The inhibitor does not compete with the substrate for the active site in uncompetitive inhibition. True or false?
true
In uncompetitive inhibition, as [S] increases, so does inhibition since ES is required for the inhibitor, there for Vmax is ____
decreased
What does uncompetitive inhibition look like on a line-weaver burk plot?
parallel lines
In the presence of an uncompetitive inhibitor, there will be an apparent Vmax ___ than the true Vmax and an apparent Km ___ than the true Km
less; less
The following version of the michaelis-menten equation describes what type of inhibition:
v = Vm[S]/1+[I]/Ki//Km/1+[I}/Ki + [S}
uncompetitive
note: a whole lot going on up top and on bottom
____ inhibitors are rare in single substrate enzymes but more common in multi-substrate enzymes
uncompetitive
