Reversible Enzyme Inhibition

Question 1

In this type of inhibition, the inhibitor competes with the substrate for the active site of the enzyme

Answer 1

competitive

Question 2

True or false? a competitive inhibitor usually has some structural similarity to the substrate

Answer 2

true

Question 3

What does a competitive inhibitor bind to?

Answer 3

free enzyme

Question 4

Competitive inhibition increases the “apparent” ___ of the enzyme

Answer 4

Km

Question 5

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

Answer 5

competitive

Question 6

What does competitive inhibition look like on lineweaver - burk plot?

Answer 6

X intercept is different but lines go through Y intercept at same point

Question 7

In competitive inhibition, Vmax is unaffected. Explain why.

Answer 7

since by increasing [S], the inhibition can be overcome and Vmax can be achieved

Question 8

___ are competitive inhibitors of the rate limiting enzyme of cholesterol biosynthesis

Answer 8

statins

Question 9

The following version of the michaelis-menten equation describes what type of inhibition:

v = Vm[S] / Km(1+[I]/Ki)+[S]

Answer 9

competitive

note: only Vm[S] is on top

Question 10

A noncompetitive inhibitor binds to either ___ or ___

Answer 10

E; ES

Question 11

Do noncompetitive inhibitors bind to the active site?

Answer 11

no, therefore don’t compete with substrate binding

Question 12

Since a noncompetitive inhibitor doesn’t compete with the S, increasing [S] will have what effect?

Answer 12

none, won’t overcome the inhibition

Question 13

A noncompetitive inhibitor decreases the “apparent” ___ of the enzyme

Answer 13

Vmax

Question 14

The effect of a ____ inhibitor is to effectively reduce the number of active enzyme molecules, which has the appearance of reducing [Etotal]

Answer 14

noncompetitive

Question 15

What does noncompetitive inhibition look like on a lineweaver-burk plot?

Answer 15

X intercepts are the same but lines cross at different points on Y intercept

Question 16

The following version of the michaelis-menten equation describes what type of inhibition:

v = Vm[S]/(1+[I]/Ki)//Km+[S]

Answer 16

noncompetitive

note: only Km + [S] on bottom

Question 17

Many heavy metals such as Hg and Pb interact with the -SH groups on enzymes and act via ____ inhibition

Answer 17

noncompetitive

Question 18

An uncompetitive inhibitor binds only to the ___ of an enzyme

Answer 18

ES

Question 19

In uncompetitive inhibition, it is proposed that substrate binding alters the enzyme structure such that…

Answer 19

the inhibitor may subsequently bind

Question 20

The inhibitor does not compete with the substrate for the active site in uncompetitive inhibition. True or false?

Answer 20

true

Question 21

In uncompetitive inhibition, as [S] increases, so does inhibition since ES is required for the inhibitor, there for Vmax is ____

Answer 21

decreased

Question 22

What does uncompetitive inhibition look like on a line-weaver burk plot?

Answer 22

parallel lines

Question 23

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

Answer 23

less; less

Question 24

The following version of the michaelis-menten equation describes what type of inhibition:

v = Vm[S]/1+[I]/Ki//Km/1+[I}/Ki + [S}

Answer 24

uncompetitive

note: a whole lot going on up top and on bottom

Question 25

____ inhibitors are rare in single substrate enzymes but more common in multi-substrate enzymes

Answer 25

uncompetitive