Question 1

What do trypsin,subtilisin,and elastase have in common?

Accepted Answer

A)  All contain Asp in the active site. 
B)  All bind hydrophobic amino acids. 
C)  All are synthesized in the pancreas. 
D)  All contain a catalytic triad at the active site. 
E)  All contain a hydrophilic substrate-binding pocket. 
A)  All contain Asp in the active site. 
B)  All bind hydrophobic amino acids. 
C)  All are synthesized in the pancreas. 
D)  All contain a catalytic triad at the active site. 
E)  All contain a hydrophilic substrate-binding pocket.

Question 2

What type of assay allows analysis of an enzyme catalyzed reaction in milliseconds?

Accepted Answer

A)  multiple wavelength absorbance spectroscopy 
B)  fluorescence lifetime 
C)  stopped-flow 
D)  NMR 
E)  None of the answers is correct. 
A)  multiple wavelength absorbance spectroscopy 
B)  fluorescence lifetime 
C)  stopped-flow 
D)  NMR 
E)  None of the answers is correct.

Question 3

Which of the following techniques allows investigators to test the role of individual amino acids in the determination of enzyme structure/function relationships even if the investigated amino acid is not present in the active site?

Accepted Answer

A)  stopped-flow assay 
B)  use of mechanism based inactivators 
C)  use of methylating agents 
D)  site-directed mutagenesis 
E)  None of the answers is correct. 
A)  stopped-flow assay 
B)  use of mechanism based inactivators 
C)  use of methylating agents 
D)  site-directed mutagenesis 
E)  None of the answers is correct.

Question 4

What caused a "burst" of activity followed by a steady-state reaction when chymotrypsin was studied by stop-flow techniques?

Accepted Answer

Chymotrypsin cleaves peptide b

Question 5

Myosins function to

Accepted Answer

A)  transfer the phosphate from NTP to NDP. 
B)  couple ATP hydrolysis to large conformational changes. 
C)  couple ATP hydrolysis to glycogen oxidation. 
D)  phosphorylate NADH. 
E)  couple ATP hydrolysis to protein synthesis in muscle. 
A)  transfer the phosphate from NTP to NDP. 
B)  couple ATP hydrolysis to large conformational changes. 
C)  couple ATP hydrolysis to glycogen oxidation. 
D)  phosphorylate NADH. 
E)  couple ATP hydrolysis to protein synthesis in muscle.

Question 6

In chymotrypsin,the tetrahedral intermediate transition state is stabilized by a structural feature referred to as the "___________________" hole.

Accepted Answer

The answer of In chymotrypsin,the tetrahedral intermediate transition state is...

Question 7

If you carried out site-directed mutagenesis of subtilisin,changing serine 221 to isoleucine,what would you expect?

Accepted Answer

A)  a large change in KM 
B)  a small change in KM  
C)  a large change in kcat 
D)  a large change in KM and a large change in kcat 
E)  a small change in KM and  a large change in kcat 
A)  a large change in KM 
B)  a small change in KM  
C)  a large change in kcat 
D)  a large change in KM and a large change in kcat 
E)  a small change in KM and  a large change in kcat

Question 8

Complete the structure of the catalytic triad of chymotrypsin by drawing the proper structure of the missing residue side chain in the box provided.Show the proper hydrogen bonding involved in this triad.

Accepted Answer

The answer of Complete the structure of the catalytic triad...

Question 9

Which of the following is an enzyme that temporarily undergoes covalent catalysis as part of its mechanism?

Accepted Answer

A)  papain 
B)  chymotrypsin 
C)  caspase 
D)  elastase 
E)  All of the answers are correct. 
A)  papain 
B)  chymotrypsin 
C)  caspase 
D)  elastase 
E)  All of the answers are correct.

Question 10

A-T base pairs,which contain _____ hydrogen bonds,are more easily interrupted than G-C base pairs with _______ hydrogen bonds.

Accepted Answer

The answer of A-T base pairs,which contain _____ hydrogen bonds,are...

Question 11

Binding of a water molecule to the zinc ion induces

Accepted Answer

A)  a hydronium ion to form. 
B)  a large conformation change in the binding site. 
C)  ionization of a His residue, which functions as a strong nucleophile. 
D)  a lowered pKa for water, which leads to formation of a zinc bound hydroxide ion. 
E)  an altered KM value. 
A)  a hydronium ion to form. 
B)  a large conformation change in the binding site. 
C)  ionization of a His residue, which functions as a strong nucleophile. 
D)  a lowered pKa for water, which leads to formation of a zinc bound hydroxide ion. 
E)  an altered KM value.

Question 12

Carbonic anhydrases are necessary because

Accepted Answer

A)  spontaneous hydration and dehydration of carbon dioxide occur very slowly. 
B)  spontaneous hydration and dehydration of carbon dioxide are rapid, but not at speeds necessary for biochemical processes. 
C)  hydration and dehydration of carbon dioxide are sometimes coupled to other biochemical processes. 
D)  spontaneous hydration and dehydration of carbon dioxide occur very slowly, and hydration and dehydration of carbon dioxide are sometimes coupled to other biochemical processes 
E)  spontaneous hydration and dehydration of carbon dioxide are rapid, but not at speeds necessary for biochemical processes, and hydration and dehydration of carbon dioxide are sometimes coupled to other biochemical processes. 
A)  spontaneous hydration and dehydration of carbon dioxide occur very slowly. 
B)  spontaneous hydration and dehydration of carbon dioxide are rapid, but not at speeds necessary for biochemical processes. 
C)  hydration and dehydration of carbon dioxide are sometimes coupled to other biochemical processes. 
D)  spontaneous hydration and dehydration of carbon dioxide occur very slowly, and hydration and dehydration of carbon dioxide are sometimes coupled to other biochemical processes 
E)  spontaneous hydration and dehydration of carbon dioxide are rapid, but not at speeds necessary for biochemical processes, and hydration and dehydration of carbon dioxide are sometimes coupled to other biochemical processes.

Question 13

What metal ion is frequently found in enzyme active sites that act on phosphate-containing substrates?

Accepted Answer

A)  Zn2+ 
B)  Mg2+ 
C)  Cu2+ 
D)  Fe2+ 
E)  Ni2+ 
A)  Zn2+ 
B)  Mg2+ 
C)  Cu2+ 
D)  Fe2+ 
E)  Ni2+

Question 14

Describe the secondary and tertiary structures in domains that form P-loops and bind phosphoryl groups.

Accepted Answer

This domain structure consists of a cent

Question 15

How can covalent modification be used to determine the mechanism of action of an enzyme?

Accepted Answer

If a particular amino acid side chain is

Question 16

What mechanism is responsible for restriction endonuclease cleavage of DNA?

Accepted Answer

An activated water molecule di

Question 17

What is the common strategy for cysteine,metallo-,and aspartyl proteases?

Accepted Answer

All employ a mechanism whereby

Question 18

What type of reaction is catalyzed by proteases?

Accepted Answer

A)  oxidation-reduction 
B)  ligation 
C)  isomerization 
D)  hydrolysis 
E)  group transfer 
A)  oxidation-reduction 
B)  ligation 
C)  isomerization 
D)  hydrolysis 
E)  group transfer

Question 19

What metal ion is required by carbonic anhydrase for activity?

Accepted Answer

A)  Zn2+ 
B)  Mg2+ 
C)  Cu2+ 
D)  Fe2+ 
E)  Ni2+ 
A)  Zn2+ 
B)  Mg2+ 
C)  Cu2+ 
D)  Fe2+ 
E)  Ni2+

Question 20

Which amino acids in chymotrypsin are found in the active site and are participants in substrate cleavage?

Accepted Answer

A)  His, Ser, Asp 
B)  His, Ser 
C)  Asp, Lys 
D)  Lys, Arg 
E)  His, Ser, Arg 
A)  His, Ser, Asp 
B)  His, Ser 
C)  Asp, Lys 
D)  Lys, Arg 
E)  His, Ser, Arg

Exam 9: Catalytic Strategies

What do trypsin,subtilisin,and elastase have in common?

What type of assay allows analysis of an enzyme catalyzed reaction in milliseconds?

Which of the following techniques allows investigators to test the role of individual amino acids in the determination of enzyme structure/function relationships even if the investigated amino acid is not present in the active site?

What caused a "burst" of activity followed by a steady-state reaction when chymotrypsin was studied by stop-flow techniques?

Myosins function to

In chymotrypsin,the tetrahedral intermediate transition state is stabilized by a structural feature referred to as the "___________________" hole.

If you carried out site-directed mutagenesis of subtilisin,changing serine 221 to isoleucine,what would you expect?

Complete the structure of the catalytic triad of chymotrypsin by drawing the proper structure of the missing residue side chain in the box provided.Show the proper hydrogen bonding involved in this triad.

Which of the following is an enzyme that temporarily undergoes covalent catalysis as part of its mechanism?

A-T base pairs,which contain _____ hydrogen bonds,are more easily interrupted than G-C base pairs with _______ hydrogen bonds.

Binding of a water molecule to the zinc ion induces

Carbonic anhydrases are necessary because

What metal ion is frequently found in enzyme active sites that act on phosphate-containing substrates?

Describe the secondary and tertiary structures in domains that form P-loops and bind phosphoryl groups.

How can covalent modification be used to determine the mechanism of action of an enzyme?

What mechanism is responsible for restriction endonuclease cleavage of DNA?

What is the common strategy for cysteine,metallo-,and aspartyl proteases?

What type of reaction is catalyzed by proteases?

What metal ion is required by carbonic anhydrase for activity?

Which amino acids in chymotrypsin are found in the active site and are participants in substrate cleavage?

Biochemistry: An Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

Oxidative Phosphorylation

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, repair, and Recombination

RNA Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

A-T base pairs,which contain _ hydrogen bonds,are more easily interrupted than G-C base pairs with ___ hydrogen bonds.