Question 1

Describe the second step of a specific-base-catalyzed dehydration of a hydrate.

Accepted Answer

A) base abstracts a proton, electron pair from O-H bond goes to oxygen 
B) negative charge from oxygen forms double bond, hydroxide departs as leaving group 
C) base abstracts a proton, electron pair from O-H bond forms a double bond, hydroxide departs as leaving group 
D) hydroxide departs as leaving group, then negative charge from oxygen forms a double bond 
E) electron pair from O-H bond forms a double bond, base abstracts a proton 
A) base abstracts a proton, electron pair from O-H bond goes to oxygen 
B) negative charge from oxygen forms double bond, hydroxide departs as leaving group 
C) base abstracts a proton, electron pair from O-H bond forms a double bond, hydroxide departs as leaving group 
D) hydroxide departs as leaving group, then negative charge from oxygen forms a double bond 
E) electron pair from O-H bond forms a double bond, base abstracts a proton B

Question 2

After lysozyme binds its substrate, the enzyme undergoes a conformational change that distorts residue D in the substrate. Which of the following best describes this distortion?

Accepted Answer

A) from a chair to a half-chair conformation 
B) from a half-chair to a chair conformation 
C) from a chair to a boat conformation 
D) from a boat to a chair conformation 
E) from a boat to a half-chair conformation 
A) from a chair to a half-chair conformation 
B) from a half-chair to a chair conformation 
C) from a chair to a boat conformation 
D) from a boat to a chair conformation 
E) from a boat to a half-chair conformation A

Question 3

Explain what is meant by site-specific mutagenesis.

Accepted Answer

It is a technique for determining the relationship between protein function and structure. This is done by substituting one amino acid of a protein for another and seeing what the effect is.

Question 4

Which of the following is not true about serine proteases?

Accepted Answer

A) They are called serine proteases because they are able to break the peptide chain at the serine linkage. 
B) Endopeptidases and serine proteases are synonyms with each other. 
C) Trypsin, chymotrypsin, and elastase are all serine proteases. 
D) Serine proteases catalyze the hydrolysis of protein peptide chains. 
E) They are called serine proteases because they all have a serine residue that participates in the catalytic process. 
A) They are called serine proteases because they are able to break the peptide chain at the serine linkage. 
B) Endopeptidases and serine proteases are synonyms with each other. 
C) Trypsin, chymotrypsin, and elastase are all serine proteases. 
D) Serine proteases catalyze the hydrolysis of protein peptide chains. 
E) They are called serine proteases because they all have a serine residue that participates in the catalytic process.

Question 5

Describe the first step of a general-base-catalyzed dehydration of a hydrate.

Accepted Answer

A) base abstracts a proton, electron pair from O-H bond goes to oxygen 
B) negative charge from oxygen forms double bond, hydroxide departs as leaving group 
C) base abstracts a proton, electron pair from O-H bond forms a double bond, hydroxide departs as leaving group 
D) hydroxide departs as leaving group, then negative charge from oxygen forms a double bond 
E) electron pair from O-H bond forms a double bond, base abstracts a proton 
A) base abstracts a proton, electron pair from O-H bond goes to oxygen 
B) negative charge from oxygen forms double bond, hydroxide departs as leaving group 
C) base abstracts a proton, electron pair from O-H bond forms a double bond, hydroxide departs as leaving group 
D) hydroxide departs as leaving group, then negative charge from oxygen forms a double bond 
E) electron pair from O-H bond forms a double bond, base abstracts a proton

Question 6

Which of the following is true of globular proteins?

Accepted Answer

A) They may be proteins with predominantly quaternary structure. 
B) They may be circular strands of short peptides. 
C) They may be three-dimensional chains of short peptides. 
D) They may be enzymes that catalyze biological reactions. 
E) They may be large strands of proteins and amylopectins. 
A) They may be proteins with predominantly quaternary structure. 
B) They may be circular strands of short peptides. 
C) They may be three-dimensional chains of short peptides. 
D) They may be enzymes that catalyze biological reactions. 
E) They may be large strands of proteins and amylopectins.

Question 7

Which of the following intermediates is produced in the second step of the mechanism for bovine chymotrypsin hydrolysis of a peptide bond?

Accepted Answer

A) epoxy-enzyme intermediate 
B) carboxy-enzyme intermediate 
C) acyl-enzyme intermediate 
D) phenoxy-enzyme intermediate 
E) oxy-enzyme intermediate 
A) epoxy-enzyme intermediate 
B) carboxy-enzyme intermediate 
C) acyl-enzyme intermediate 
D) phenoxy-enzyme intermediate 
E) oxy-enzyme intermediate

Question 8

Explain what is meant by anchimeric assistance and give an example.

Accepted Answer

In Greek, anchimeric means "ad

Question 9

Which amino acid component of an enzyme has a chain that can form an imine with the substrate?

Accepted Answer

A) lysine 
B) methionine 
C) phenylalanine 
D) serine 
E) aspartic acid 
A) lysine 
B) methionine 
C) phenylalanine 
D) serine 
E) aspartic acid

Question 10

Describe the acid-catalyzed first slow step in the hydrolysis of an ester.

Accepted Answer

A) The electron pair on oxygen forms double bond and alcohol is the leaving group. 
B) The base abstracts extra hydrogen from protonated alcohol. 
C) The oxygen of the carbonyl group abstracts a hydrogen from HB. 
D) Water attacks the carbonyl carbon and electron pair goes to oxygen. 
E) The oxygen on the alkoxy group abstracts a hydrogen from HB. 
A) The electron pair on oxygen forms double bond and alcohol is the leaving group. 
B) The base abstracts extra hydrogen from protonated alcohol. 
C) The oxygen of the carbonyl group abstracts a hydrogen from HB. 
D) Water attacks the carbonyl carbon and electron pair goes to oxygen. 
E) The oxygen on the alkoxy group abstracts a hydrogen from HB.

Question 11

The enzyme lysozyme exhibits greatest activity in solutions where the pH is maintained between 3.8 and 6.7. Which of the following conclusions about the Asp 52 and Glu 35 residues in the enzyme's active site can be reached?

Accepted Answer

A) Lysozyme is maximally active when both Asp 52 and Glu 35 are in their acidic forms. 
B) Lysozyme is maximally active when both Asp 52 and Glu 35 are in their basic forms. 
C) Lysozyme is maximally active when both Asp 52 and Glu 35 are in their neutral forms. 
D) Lysozyme is maximally active when Asp 52 is in its acidic form and Glu 35 is in its basic form. 
E) Lysozyme is maximally active when Asp 52 is in its basic form and Glu 35 is in its acidic form. 
A) Lysozyme is maximally active when both Asp 52 and Glu 35 are in their acidic forms. 
B) Lysozyme is maximally active when both Asp 52 and Glu 35 are in their basic forms. 
C) Lysozyme is maximally active when both Asp 52 and Glu 35 are in their neutral forms. 
D) Lysozyme is maximally active when Asp 52 is in its acidic form and Glu 35 is in its basic form. 
E) Lysozyme is maximally active when Asp 52 is in its basic form and Glu 35 is in its acidic form.

Question 12

Stabilization of a charge by an opposite charge is called ________ catalysis.

Accepted Answer

A) electrostatic 
B) osmotic 
C) substrate 
D) activated 
E) covalent 
A) electrostatic 
B) osmotic 
C) substrate 
D) activated 
E) covalent

Question 13

Give the starting materials for the following products.

Accepted Answer

The answer of Give the starting materials for the following...

Question 14

Which of the following is a step in the mechanism of the reaction shown below?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 15

Which of the following statements best describes what lysozyme is?

Accepted Answer

A) an enzyme that destroys the cell walls of bacteria 
B) an enzyme that repairs the cell walls of bacteria 
C) an enzyme that hydrolyzes the NAM-NAG bond 
D) A and C 
E) B and C 
A) an enzyme that destroys the cell walls of bacteria 
B) an enzyme that repairs the cell walls of bacteria 
C) an enzyme that hydrolyzes the NAM-NAG bond 
D) A and C 
E) B and C

Question 16

Which of the following is an intermediate in the metal-ion catalyzed reaction shown below?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 17

Which of the following is the main difference among the active sites of all serine proteases?

Accepted Answer

A) The presence of serine residue at the active site 
B) The size and charge of the pocket at the active site 
C) The presence of histidine residue at the active site 
D) The presence of aspartate at the active site 
E) The hydrolysis of the peptide bond 
A) The presence of serine residue at the active site 
B) The size and charge of the pocket at the active site 
C) The presence of histidine residue at the active site 
D) The presence of aspartate at the active site 
E) The hydrolysis of the peptide bond

Question 18

How does Cu2+ catalyze the decarboxylation of dimethyloxaloacetate?

Accepted Answer

Cu²⁺ binds to two oxygen atoms a

Question 19

Which of the following statements about how acid catalyzes the hydrolysis of esters is (are)correct?

Accepted Answer

A) The acid catalyst increases the rate of formation of the tetrahedral intermediate by protonating the carbonyl and thereby increasing the reactivity of the carbonyl group. 
B) The acid catalyst increases the rate of the reaction by changing the basicity of the group eliminated when the tetrahedral intermediate collapses. 
C) The acid catalyst protonates the water, the nucleophile in the reaction, and thereby makes it a stronger nucloephile. 
D) both A and B 
E) all of the above 
A) The acid catalyst increases the rate of formation of the tetrahedral intermediate by protonating the carbonyl and thereby increasing the reactivity of the carbonyl group. 
B) The acid catalyst increases the rate of the reaction by changing the basicity of the group eliminated when the tetrahedral intermediate collapses. 
C) The acid catalyst protonates the water, the nucleophile in the reaction, and thereby makes it a stronger nucloephile. 
D) both A and B 
E) all of the above

Question 20

Which amino acid component is most likely to serve as a proton donor in an enzyme's active site?

Accepted Answer

A) methionine 
B) glutamic acid 
C) valine 
D) phenylalanine 
E) pyroline 
A) methionine 
B) glutamic acid 
C) valine 
D) phenylalanine 
E) pyroline

Exam 23: Catalysis

Describe the second step of a specific-base-catalyzed dehydration of a hydrate.

After lysozyme binds its substrate, the enzyme undergoes a conformational change that distorts residue D in the substrate. Which of the following best describes this distortion?

Explain what is meant by site-specific mutagenesis.

Which of the following is not true about serine proteases?

Describe the first step of a general-base-catalyzed dehydration of a hydrate.

Which of the following is true of globular proteins?

Which of the following intermediates is produced in the second step of the mechanism for bovine chymotrypsin hydrolysis of a peptide bond?

Explain what is meant by anchimeric assistance and give an example.

Which amino acid component of an enzyme has a chain that can form an imine with the substrate?

Describe the acid-catalyzed first slow step in the hydrolysis of an ester.

The enzyme lysozyme exhibits greatest activity in solutions where the pH is maintained between 3.8 and 6.7. Which of the following conclusions about the Asp 52 and Glu 35 residues in the enzyme's active site can be reached?

Stabilization of a charge by an opposite charge is called ________ catalysis.

Give the starting materials for the following products.

Which of the following is a step in the mechanism of the reaction shown below?

Which of the following statements best describes what lysozyme is?

Which of the following is an intermediate in the metal-ion catalyzed reaction shown below?

Which of the following is the main difference among the active sites of all serine proteases?

How does Cu2+ catalyze the decarboxylation of dimethyloxaloacetate?

Which of the following statements about how acid catalyzes the hydrolysis of esters is (are)correct?

Which amino acid component is most likely to serve as a proton donor in an enzyme's active site?

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds

Isomers: the Arrangement of Atoms in Space

Alkenes Thermodynamics and Kinetics

Reactions of Alkenes

Reactions of Alkynes Introduction to Multistep Synthesis

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Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

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Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

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Reactions of Benzene and Substituted Benzenes

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How does Cu²⁺ catalyze the decarboxylation of dimethyloxaloacetate?