Question 1

Which of the following is true about enzymes?

Accepted Answer

Enzyme activities can often be regulated through various mechanisms such as allosteric regulation, covalent modification, and changes in enzyme concentration.

Question 2

How is an enzyme-catalyzed reaction affected by the addition of more enzyme?

Accepted Answer

The velocity of an enzyme-catalyzed reaction will increase with the addition of more enzyme, assuming there is an excess of substrate available.

Question 3

For a reaction A + B $\rarr$ C, if [B] is much larger than [A] so that [B] essentially remains constant over the course of the reaction, the kinetics will be _____.

Accepted Answer

When one reactant is in large excess, its concentration remains effectively constant, simplifying the rate law to depend only on the concentration of the other reactant, making it pseudo first-order.

Question 4

Which of the following properly expresses the Michaelis-Menten equation?

Accepted Answer

The Michaelis-Menten equation is v_o = V_max [S] / (K_M + [S]), which describes the rate of enzymatic reactions by relating reaction rate v_o to substrate concentration [S], maximum rate V_max, and the Michaelis constant K_M.

Question 5

When is K_M considered to be the same as the dissociation constant for the ES complex i.e., K_M $\approx$ [E] [S] / [ES].

Accepted Answer

When k₂ << k_-1, K_M approximates the dissociation constant K_d = k_-1/k₁ because the breakdown of ES to E + S is much faster than the conversion of ES to E + P.

Question 6

What percentage of V_max is obtained when the substrate is present at ¼ of the K_M? `

Accepted Answer

According to the Michaelis-Menten equation, when the substrate concentration [S] is ¼ of the K_M, the velocity (v) is 20% of V_max.

Question 7

Which of the following must be true for an enzymatic reaction obeying the Michaelis-Menten equation to reach 3/4 of its maximum velocity?

Accepted Answer

The answer of Which of the following must be true...

Question 8

Which of the following types of enzyme-catalyzed reactions follows non-Michaelis-Menten kinetics?

Accepted Answer

The answer of Which of the following types of enzyme-catalyzed...

Question 9

In a bisubstrate reaction, reactant A binds, followed by reactant B which then get converted to products C and D. An experiment showed that B cannot bind without A having bound first. What mechanism is indicated by this data?

Accepted Answer

The data indicates an ordered mechanism because reactant A must bind first before reactant B can bind, suggesting a specific sequence of binding.

Question 10

In a bisubstrate reaction, reactant A binds and is then converted to product C. Next, reactant B binds and is then converted to product D. An experiment showed that B cannot bind without C being released first. What mechanism is indicated by this data?

Accepted Answer

The data indicates a ping pong mechanism, where one substrate binds and is converted to a product before the second substrate can bind.

Question 11

How are the kinetics of an enzyme-catalyzed reaction affected by a competitive inhibitor?

Accepted Answer

A competitive inhibitor increases the apparent K_M because it competes with the substrate for the active site, but it does not affect V_max because the inhibition can be overcome by increasing substrate concentration.

Question 12

If a Lineweaver-Burk plot was made for an enzyme-catalyzed reaction, both with and without a competitive inhibitor present, what difference would be seen?

Accepted Answer

The answer of If a Lineweaver-Burk plot was made for...

Question 13

What type of inhibition explains why even at very high substrate concentrations, enzyme activity will decrease as time increases?

Accepted Answer

Product inhibition occurs when the product of an enzymatic reaction accumulates and inhibits the enzyme's activity, leading to a decrease in enzyme activity over time even at high substrate concentrations.

Question 14

Which of the following is true regarding transition state analogs?

Accepted Answer

Transition state analogs are designed to mimic the transition state of a substrate in an enzyme-catalyzed reaction. They often act as competitive inhibitors (A), bind with high affinity to the enzyme's active site (B), are more stable than the actual transition state (C), and typically have greater affinity for the enzyme than the substrate itself (D).

Question 15

How are the kinetics of an enzyme-catalyzed reaction affected by a purely noncompetitive inhibitor?

Accepted Answer

A purely noncompetitive inhibitor decreases the Vmax because it affects the enzyme's ability to catalyze the reaction, but it does not change the Km because it does not affect the binding of the substrate to the enzyme.

Question 16

If a Lineweaver-Burk plot was made for an enzyme-catalyzed reaction, both with and without a noncompetitive inhibitor present, what difference would be seen?

Accepted Answer

In the presence of a noncompetitive inhibitor, the Vmax decreases, which increases the y-intercept on a Lineweaver-Burk plot. The slope also increases because Km remains unchanged while Vmax decreases.

Question 17

How are the kinetics of an enzyme-catalyzed reaction affected by a mixed inhibitor?

Accepted Answer

Mixed inhibitors bind to both the free enzyme and the enzyme-substrate complex, causing a decrease in Vmax and a change in Km.

Question 18

Acyclovir is an analog of ___ that lacks interferes with ___.

Accepted Answer

The answer of Acyclovir is an analog of ___ that...

Question 19

Find the initial velocity for an enzymatic reaction when V_max = 6.5 × 10^-5 mol•sec^-1, [S] = 3.0 × 10^-3 M, K_M = 4.5 × 10^-3 M, and the enzyme concentration at time zero is 1.5 × 10^-2$\mu$M.

Accepted Answer

The answer of Find the initial velocity for an enzymatic...

Question 20

The Michaelis constant KM is defined as _____.
I. (k-1 + k2)/k1
II. one-half Vmax
III. [S] = [ES]
IV. [ES]/2

Accepted Answer

The Michaelis constant KM is defined as (k-1 + k2)/k1, which is option I. It represents the substrate concentration at which the reaction rate is half of Vmax, but it is not equal to one-half Vmax itself.

Quiz 7: Enzyme Kinetics and Inhibition

Which of the following is true about enzymes?

How is an enzyme-catalyzed reaction affected by the addition of more enzyme?

For a reaction A + B $\rarr$ C, if [B] is much larger than [A] so that [B] essentially remains constant over the course of the reaction, the kinetics will be _____.

Which of the following properly expresses the Michaelis-Menten equation?

When is K_M considered to be the same as the dissociation constant for the ES complex i.e., K_M $\approx$ [E] [S] / [ES].

What percentage of V_max is obtained when the substrate is present at ¼ of the K_M? `

Which of the following must be true for an enzymatic reaction obeying the Michaelis-Menten equation to reach 3/4 of its maximum velocity?

Which of the following types of enzyme-catalyzed reactions follows non-Michaelis-Menten kinetics?

In a bisubstrate reaction, reactant A binds, followed by reactant B which then get converted to products C and D. An experiment showed that B cannot bind without A having bound first. What mechanism is indicated by this data?

In a bisubstrate reaction, reactant A binds and is then converted to product C. Next, reactant B binds and is then converted to product D. An experiment showed that B cannot bind without C being released first. What mechanism is indicated by this data?

How are the kinetics of an enzyme-catalyzed reaction affected by a competitive inhibitor?

If a Lineweaver-Burk plot was made for an enzyme-catalyzed reaction, both with and without a competitive inhibitor present, what difference would be seen?

What type of inhibition explains why even at very high substrate concentrations, enzyme activity will decrease as time increases?

Which of the following is true regarding transition state analogs?

How are the kinetics of an enzyme-catalyzed reaction affected by a purely noncompetitive inhibitor?

If a Lineweaver-Burk plot was made for an enzyme-catalyzed reaction, both with and without a noncompetitive inhibitor present, what difference would be seen?

How are the kinetics of an enzyme-catalyzed reaction affected by a mixed inhibitor?

Acyclovir is an analog of _ that lacks interferes with _.

Find the initial velocity for an enzymatic reaction when V_max = 6.5 × 10^-5 mol•sec^-1, [S] = 3.0 × 10^-3 M, K_M = 4.5 × 10^-3 M, and the enzyme concentration at time zero is 1.5 × 10^-2 $\mu$ M.

The Michaelis constant KM is defined as _____. I. (k-1 + k2) /k1 II. one-half Vmax III. [S] = [ES] IV. [ES]/2

Quiz 7: Enzyme Kinetics and Inhibition

Which of the following is true about enzymes?

How is an enzyme-catalyzed reaction affected by the addition of more enzyme?

For a reaction A + B →\rarr→ C, if [B] is much larger than [A] so that [B] essentially remains constant over the course of the reaction, the kinetics will be _____.

Which of the following properly expresses the Michaelis-Menten equation?

When is KM considered to be the same as the dissociation constant for the ES complex i.e., KM ≈\approx≈ [E] [S] / [ES].

What percentage of Vmax is obtained when the substrate is present at ¼ of the KM? `

Which of the following must be true for an enzymatic reaction obeying the Michaelis-Menten equation to reach 3/4 of its maximum velocity?

Which of the following types of enzyme-catalyzed reactions follows non-Michaelis-Menten kinetics?

In a bisubstrate reaction, reactant A binds, followed by reactant B which then get converted to products C and D. An experiment showed that B cannot bind without A having bound first. What mechanism is indicated by this data?

In a bisubstrate reaction, reactant A binds and is then converted to product C. Next, reactant B binds and is then converted to product D. An experiment showed that B cannot bind without C being released first. What mechanism is indicated by this data?

How are the kinetics of an enzyme-catalyzed reaction affected by a competitive inhibitor?

If a Lineweaver-Burk plot was made for an enzyme-catalyzed reaction, both with and without a competitive inhibitor present, what difference would be seen?

What type of inhibition explains why even at very high substrate concentrations, enzyme activity will decrease as time increases?

Which of the following is true regarding transition state analogs?

How are the kinetics of an enzyme-catalyzed reaction affected by a purely noncompetitive inhibitor?

If a Lineweaver-Burk plot was made for an enzyme-catalyzed reaction, both with and without a noncompetitive inhibitor present, what difference would be seen?

How are the kinetics of an enzyme-catalyzed reaction affected by a mixed inhibitor?

Acyclovir is an analog of ___ that lacks interferes with ___.

Find the initial velocity for an enzymatic reaction when Vmax = 6.5 × 10-5 mol•sec-1, [S] = 3.0 × 10-3 M, KM = 4.5 × 10-3 M, and the enzyme concentration at time zero is 1.5 × 10-2 μ\muμ M.

The Michaelis constant KM is defined as _____. I. (k-1 + k2) /k1 II. one-half Vmax III. [S] = [ES] IV. [ES]/2

For a reaction A + B $\rarr$ C, if [B] is much larger than [A] so that [B] essentially remains constant over the course of the reaction, the kinetics will be _____.

When is K_M considered to be the same as the dissociation constant for the ES complex i.e., K_M $\approx$ [E] [S] / [ES].

What percentage of V_max is obtained when the substrate is present at ¼ of the K_M? `

Acyclovir is an analog of _ that lacks interferes with _.

Find the initial velocity for an enzymatic reaction when V_max = 6.5 × 10^-5 mol•sec^-1, [S] = 3.0 × 10^-3 M, K_M = 4.5 × 10^-3 M, and the enzyme concentration at time zero is 1.5 × 10^-2 $\mu$ M.