Question 1

Simultaneous stimulation of a reaction by general acid and general base catalysis is defined as

Accepted Answer

A) covalent catalysis. 
B) electrostatic catalysis. 
C) proximity catalysis. 
D) concerted acid-base catalysis. 
E) transition state catalysis. 
A) covalent catalysis. 
B) electrostatic catalysis. 
C) proximity catalysis. 
D) concerted acid-base catalysis. 
E) transition state catalysis. D

Question 2

Lysozyme requires _____ for effective catalysis.
I.an Asp in a nonpolar environment
II.a negatively charged Asp
III.a Glu that functions as an acid catalyst
IV.a Glu that is deprotonated

Accepted Answer

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

Question 3

In the lysozome reaction the D ring in NAM is in the ________ conformation providing a contribution of catalytic energy via the ____ distortion.

Accepted Answer

A) half-chair; electrostatic 
B) chair; strain 
C) boat; strain 
D) boat; electrostatic 
E) half-chair; strain 
A) half-chair; electrostatic 
B) chair; strain 
C) boat; strain 
D) boat; electrostatic 
E) half-chair; strain E

Question 4

Enzyme X catalyzes the addition of a hydroxyl group to substrate Y.In the process a metal cofactor is reduced and then reoxidized.What class of enzyme is X?

Accepted Answer

A) oxidoreductase 
B) ligase 
C) hydrolase 
D) isomerase 
E) lyase 
A) oxidoreductase 
B) ligase 
C) hydrolase 
D) isomerase 
E) lyase

Question 5

Carbohydrate metabolic enzymes bind D-glucose specifically.D-glucose has an estimated caloric value of 1 kcal per 4 grams of carbohydrate.Based on the methods used to convert the energy of D-glucose into a useable form, what would you estimate the caloric value of L-glucose to be using the same method?

Accepted Answer

A) 1 kcal per 4 grams 
B) 1 kcal per 2 grams 
C) 1 kcal per 8 grams 
D) 0 kcal per 4 grams 
E) 2 kcal per 8 grams 
A) 1 kcal per 4 grams 
B) 1 kcal per 2 grams 
C) 1 kcal per 8 grams 
D) 0 kcal per 4 grams 
E) 2 kcal per 8 grams

Question 6

Proton transfer from an acid, lowering the free energy of a reaction's transition state, is characteristic of

Accepted Answer

A) electrostatic catalysis. 
B) nucleophilic catalysis. 
C) general base catalysis. 
D) general acid catalysis. 
E) concerted acid-base catalysis. 
A) electrostatic catalysis. 
B) nucleophilic catalysis. 
C) general base catalysis. 
D) general acid catalysis. 
E) concerted acid-base catalysis.

Question 7

In the serine protease trypsin, the specificity for one substrate over another describes what type of catalysis?

Accepted Answer

A) proximity 
B) acid-base 
C) covalent 
D) strain 
E) none of the above 
A) proximity 
B) acid-base 
C) covalent 
D) strain 
E) none of the above

Question 8

Which of the following is TRUE about enzymes?
I.Enzymes typically catalyze reactions at much higher rates than chemical catalyst.
II.Enzymes are often very specific for their substrates.
III.Enzyme activities can often be regulated.
IV.Enzymes typically act under milder conditions of temperature and pH than chemical catalysts.

Accepted Answer

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

Question 9

A pH versus rate curve with an inflection point at pH~4 suggests the involvement of a(n)________ in the catalytic step.

Accepted Answer

A) proton abstraction that requires a metal ion in close proximity 
B) proton transfer with a pK close to 4 
C) proton donation that is mediated by a coenzyme 
D) free proton surrounded by a hydrophobic environment 
E) redox cofactor 
A) proton abstraction that requires a metal ion in close proximity 
B) proton transfer with a pK close to 4 
C) proton donation that is mediated by a coenzyme 
D) free proton surrounded by a hydrophobic environment 
E) redox cofactor

Question 10

Acid-base catalysis may be accomplished by:

Accepted Answer

A) active site specificity 
B) charge delocalization 
C) buffer effects 
D) induced strain 
E) conformational change 
A) active site specificity 
B) charge delocalization 
C) buffer effects 
D) induced strain 
E) conformational change

Question 11

Which of the following amino acid residues would provide a side chain capable of increasing the hydrophobicity of a binding site?

Accepted Answer

A) histidine 
B) lysine 
C) isoleucine 
D) arginine 
E) serine 
A) histidine 
B) lysine 
C) isoleucine 
D) arginine 
E) serine

Question 12

Matching
-Clustering several amino acid residues with appropriate pK values at an active site can promote a(n)_________ catalytic mechanism.

Accepted Answer

A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation 
A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation

Question 13

Research scientists are trying to clone a gene.In order to accomplish this task they join two pieces of DNA.Which class of the enzymes below might accomplish this task?

Accepted Answer

A) oxidoreductase 
B) ligase 
C) hydrolase 
D) isomerase 
E) lyase 
A) oxidoreductase 
B) ligase 
C) hydrolase 
D) isomerase 
E) lyase

Question 14

Which one of the following is correct?
I.All enzymes are highly specific for the reactions they catalyze.
II.Prosthetic groups are loosely associated with the polypeptide chain of an enzyme.
III.If an enzyme-catalyzed reaction requires a group with a low pK to be deprotonated and a group with a higher pK to be protonated, the pH vs.rate curve will have a peak in the middle of the two pK values.
IV.When comparing types of catalysis, the proximity effect provides the largest rate enhancement.

Accepted Answer

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

Question 15

During the course of a catalytic reaction the following occurs: 1)Substrate is covalently bound and oriented with proximity to the active site residues.2)Negative charge builds up on the substrate and is stabilized.3)Oxidation of the enzyme followed by reduction to complete the catalytic cycle.What type of chemical species can facilitate these reactions?

Accepted Answer

A) nucleophilic amino acids 
B) electrophilic groups 
C) prosthetic phosphate groups 
D) transition metal anions 
E) transition metal cations 
A) nucleophilic amino acids 
B) electrophilic groups 
C) prosthetic phosphate groups 
D) transition metal anions 
E) transition metal cations

Question 16

Matching
-Some serine proteases are believed to have developed by convergent evolution, because the ______ sequences of some serine proteases show no resemblance to those of others.

Accepted Answer

A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation 
A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation

Question 17

Matching
-Metal ion cofactors offer various ______ states that allow enzymes to accomplished oxidation reduction reactions.

Accepted Answer

A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation 
A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation

Question 18

The enzyme pictured below is shown in two configurations, A (open)and B (closed).Upon binding substrate in the active site, the enzyme converts the structure shown in B.Which of the following is true based on the given information?

Accepted Answer

A) The enzyme requires a high concentration of substrate to function 
B) This example exemplifies the "lock-and-key" model. 
C) This enzyme must require ATP. 
D) This example exemplifies the of "induced fit" model. 
E) None of these are true. 
A) The enzyme requires a high concentration of substrate to function 
B) This example exemplifies the "lock-and-key" model. 
C) This enzyme must require ATP. 
D) This example exemplifies the of "induced fit" model. 
E) None of these are true.

Question 19

Matching
-On a transition state diagram for a one-step very spontaneous reaction a large peak (high $\Delta$ G‡)would imply a ______ rate for the reaction.

Accepted Answer

A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation 
A) high 
B) deprotonated 
C) protonated 
D) catalytic mechanism 
E) covalent
F)rate-determining step
G)leaving group
H)formation of ES
I)amino acid
J)low
K)coenzymes
L)concerted acid-base
M)orientation
N)oxidation

Question 20

Which type of catalysis may be carried out using redistribution of electron density to facilitate the transfer of a proton?
I.proximity
II.acid-base
III.covalent
IV.strain

Accepted Answer

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

Exam 11: Enzyme Catalysis

Simultaneous stimulation of a reaction by general acid and general base catalysis is defined as

Lysozyme requires _____ for effective catalysis. I.an Asp in a nonpolar environment II.a negatively charged Asp III.a Glu that functions as an acid catalyst IV.a Glu that is deprotonated

In the lysozome reaction the D ring in NAM is in the ________ conformation providing a contribution of catalytic energy via the ____ distortion.

Enzyme X catalyzes the addition of a hydroxyl group to substrate Y.In the process a metal cofactor is reduced and then reoxidized.What class of enzyme is X?

Proton transfer from an acid, lowering the free energy of a reaction's transition state, is characteristic of

In the serine protease trypsin, the specificity for one substrate over another describes what type of catalysis?

A pH versus rate curve with an inflection point at pH~4 suggests the involvement of a(n)________ in the catalytic step.

Acid-base catalysis may be accomplished by:

Which of the following amino acid residues would provide a side chain capable of increasing the hydrophobicity of a binding site?

Matching -Clustering several amino acid residues with appropriate pK values at an active site can promote a(n)_________ catalytic mechanism.

Research scientists are trying to clone a gene.In order to accomplish this task they join two pieces of DNA.Which class of the enzymes below might accomplish this task?

Matching -Some serine proteases are believed to have developed by convergent evolution, because the ______ sequences of some serine proteases show no resemblance to those of others.

Matching -Metal ion cofactors offer various ______ states that allow enzymes to accomplished oxidation reduction reactions.

The enzyme pictured below is shown in two configurations, A (open)and B (closed).Upon binding substrate in the active site, the enzyme converts the structure shown in B.Which of the following is true based on the given information?

Matching -On a transition state diagram for a one-step very spontaneous reaction a large peak (high Δ\DeltaΔ G‡)would imply a ______ rate for the reaction.

Which type of catalysis may be carried out using redistribution of electron density to facilitate the transfer of a proton? I.proximity II.acid-base III.covalent IV.strain

Introduction to the Chemistry of Life

Water

Nucleotides, Nucleic Acids, and Genetic Information

Amino Acids

Proteins: Primary Structure

Proteins: Three-Dimensional Structure

Protein Function Part I: Myoglobin and Hemoglobin

Carbohydrates

Lipids and Biological Membranes

Membrane Transport

Enzyme Kinetics, Inhibition and Control

Biochemical Signaling

Introduction to Metabolism

Glycogen Metabolism and Gluconeogenesis

Glucose Catabolism

Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Mammalian Fuel Metabolism: Integration and Regulation

Nucleotide Metabolism

Nucleic Acid Structure

Dna Replication, Repair and Recombination

Transcription and Rna Processing

Translation

Regulation of Gene Expression

Filters

In the lysozome reaction the D ring in NAM is in the ____ conformation providing a contribution of catalytic energy via the distortion.

Matching -On a transition state diagram for a one-step very spontaneous reaction a large peak (high $\Delta$ G^‡)would imply a ______ rate for the reaction.