Question 1

Proximity effects

Accepted Answer

A) result from active site specificity. 
B) result from substrate channeling. 
C) result in increased effective concentration of substrate. 
D) lower the energy of activation. 
E) All of the above of the above are correct. 
A) result from active site specificity. 
B) result from substrate channeling. 
C) result in increased effective concentration of substrate. 
D) lower the energy of activation. 
E) All of the above of the above are correct.

Question 2

The following diagram shows a portion of a reaction sequence of an enzyme.What type(s)of catalysis is (are)occurring in this first step?

Accepted Answer

A) proximity catalysis 
B) acid-base catalysis 
C) covalent catalysis 
D) All of the above are occurring. 
E) None of the above is occurring. 
A) proximity catalysis 
B) acid-base catalysis 
C) covalent catalysis 
D) All of the above are occurring. 
E) None of the above is occurring.

Question 3

In trypsin the specificity for one substrate over another comes from

Accepted Answer

A) the negatively charged pocket. 
B) the positively charge pocket. 
C) the hydrophobic pocket. 
D) the amino acid serine. 
E) the amino acid histidine. 
A) the negatively charged pocket. 
B) the positively charge pocket. 
C) the hydrophobic pocket. 
D) the amino acid serine. 
E) the amino acid histidine.

Question 4

Alcohol dehydrogenase catalyzes the conversion of methanol to _________ and is, therefore, classified as a(an)________.

Accepted Answer

A) acetic acid; transferase 
B) formaldehyde; oxidoreductase 
C) acetic acid; oxidoreductase 
D) ethanol; lyase 
E) formaldehyde; transferase 
A) acetic acid; transferase 
B) formaldehyde; oxidoreductase 
C) acetic acid; oxidoreductase 
D) ethanol; lyase 
E) formaldehyde; transferase

Question 5

The catalytic mechanism of bovine pancreatic RNase A relies upon acid-base catalysis involving the amino acid __________.

Accepted Answer

A) imidazole 
B) lysine 
C) histidine 
D) aspartic acid 
E) glutamic acid 
A) imidazole 
B) lysine 
C) histidine 
D) aspartic acid 
E) glutamic acid

Question 6

Matching
-Since proteins are limited in their abilities to catalyze oxidation-reduction reactions, enzymes often employ ______ to assist with catalysis.

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 7

Glu 35 of lysozyme is found in a nonpolar environment.Which of the following is true?

Accepted Answer

A) Its pK is lower than the usual value in this environment. 
B) Its pK is higher than the usual value in this environment. 
C) Its pK would not change in this environment. 
D) Its pK would depend on the sample buffer. 
E) None of the above is correct. 
A) Its pK is lower than the usual value in this environment. 
B) Its pK is higher than the usual value in this environment. 
C) Its pK would not change in this environment. 
D) Its pK would depend on the sample buffer. 
E) None of the above is correct.

Question 8

Matching
-Metal ion cofactors can coordinate to the substrate or stabilize electrostatic effects by enabling proper ______in the active site.

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 9

Which of the following amino acid residues would not provide a side chain for acid-base catalysis at physiological pH? (Assume pK values of each amino acid are equal to the pK value for the free amino acid in solution.)
I.leucine
II.lysine
III.aspartic acid
IV.histidine

Accepted Answer

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

Question 10

Matching
-For efficient nucleophilic catalysis, a group such as the sulfhydryl on a cysteine residue must be able to form a good ______, in addition to being a good nucleophile.

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 11

The transition state of an enzyme and substrate reaction

Accepted Answer

A) must always bind the enzyme active site with lower energy than the products. 
B) is stabilized by enhancing the reverse reaction of E + S→ES. 
C) is composed of true covalent bonds which decrease its energy. 
D) is stabilized due to the specificity of the active site for the substrate. 
E) is stabilized by decreasing the effective concentration. 
A) must always bind the enzyme active site with lower energy than the products. 
B) is stabilized by enhancing the reverse reaction of E + S→ES. 
C) is composed of true covalent bonds which decrease its energy. 
D) is stabilized due to the specificity of the active site for the substrate. 
E) is stabilized by decreasing the effective concentration.

Question 12

Matching
-On a transition state diagram for a multistep reaction, the step with the greatest $\Delta$G is the ______.

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

Matching
-Large rate enhancement in enzyme catalysis may occur when binding the substrate via _________ attachment.

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

Exam 11: Enzyme Catalysis

Proximity effects

The following diagram shows a portion of a reaction sequence of an enzyme.What type(s)of catalysis is (are)occurring in this first step?

In trypsin the specificity for one substrate over another comes from

Alcohol dehydrogenase catalyzes the conversion of methanol to _________ and is, therefore, classified as a(an)________.

The catalytic mechanism of bovine pancreatic RNase A relies upon acid-base catalysis involving the amino acid __________.

Matching -Since proteins are limited in their abilities to catalyze oxidation-reduction reactions, enzymes often employ ______ to assist with catalysis.

Glu 35 of lysozyme is found in a nonpolar environment.Which of the following is true?

Matching -Metal ion cofactors can coordinate to the substrate or stabilize electrostatic effects by enabling proper ______in the active site.

Which of the following amino acid residues would not provide a side chain for acid-base catalysis at physiological pH? (Assume pK values of each amino acid are equal to the pK value for the free amino acid in solution.) I.leucine II.lysine III.aspartic acid IV.histidine

Matching -For efficient nucleophilic catalysis, a group such as the sulfhydryl on a cysteine residue must be able to form a good ______, in addition to being a good nucleophile.

The transition state of an enzyme and substrate reaction

Matching -On a transition state diagram for a multistep reaction, the step with the greatest Δ\DeltaΔ G is the ______.

Matching -Large rate enhancement in enzyme catalysis may occur when binding the substrate via _________ attachment.

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

Alcohol dehydrogenase catalyzes the conversion of methanol to _ and is, therefore, classified as a(an).

Matching -On a transition state diagram for a multistep reaction, the step with the greatest $\Delta$ G is the ______.