Question 1

Which type of reaction is catalyzed by chorismate mutase in the conversion of chorismate to prephenate?

Accepted Answer

A [3,3]-sigmatropic rearrangement

Question 2

What is the key intermediate structure formed during the chorismate mutase reaction?

Accepted Answer

A bicyclic transition state

Question 3

Which amino acid residue in the BsCM active site is most likely to stabilize the negative charge developed on the oxygen atom during the transition state?

Accepted Answer

Arginine

Question 4

The Claisen rearrangement shown in the study materials is best described as:

Accepted Answer

A pericyclic reaction involving a [3,3]-sigmatropic shift

Question 5

Which of the following best describes the role of the enzyme chorismate mutase in the reaction mechanism?

Accepted Answer

It stabilizes the transition state, lowering the activation energy

Question 6

In the chorismate mutase reaction, which bonds are broken and formed during the rearrangement?

Accepted Answer

A C–O bond is broken and a new C–C bond is formed

Question 7

Which of the following is a product of the Claisen rearrangement of allyl phenyl ether?

Accepted Answer

$$	ext{2-Allyl phenol}$$

Question 8

What is the significance of the keto-enol tautomerization step in the Claisen rearrangement pathway?

Accepted Answer

It converts the cyclohexadienone intermediate into the final phenolic product

Question 9

Which of the following best explains why the chorismate mutase reaction is considered a pericyclic reaction?

Accepted Answer

It proceeds via a concerted cyclic transition state involving the redistribution of bonding electrons

Question 10

In the context of enzyme catalysis, what is the primary function of the amino acid side chains shown interacting with the transition state in the BsCM active site?

Accepted Answer

To stabilize the transition state through hydrogen bonding and electrostatic interactions

Question 11

Which of the following statements about the mechanism of the chorismate mutase reaction is correct?

Accepted Answer

The reaction involves a concerted [3,3]-sigmatropic rearrangement without discrete intermediates

Question 12

Which of the following best describes the structural change from chorismate to prephenate?

Accepted Answer

A six-membered ring is converted to a bicyclic system and then to a different six-membered ring

Question 13

Which of the following is NOT a feature of the Claisen rearrangement mechanism?

Accepted Answer

Formation of a carbocation intermediate

Question 14

In the context of the chorismate mutase reaction, which of the following best explains the enzyme's specificity for chorismate over other similar substrates?

Accepted Answer

The active site is complementary in shape and charge to chorismate, allowing precise binding and transition state stabilization

Question 15

Which of the following best describes the role of Glu 78 in the BsCM active site?

Accepted Answer

It forms a hydrogen bond with the substrate, stabilizing the transition state

Claisen Rearrangement and Chorismate Mutase Reaction Mechanisms

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