Question 1

In Cys-Ile-Ser-Asp-Gly-His-Gly-Gly, the three-letter abbreviation for the N-terminal amino acid is ________.

Accepted Answer

Cys

Question 2

Provide the structure of dicylcohexylcarbodiimide, a common reagent that is used to couple two amino acid residues by formation of a peptide bond, and the structure N,N'-dicyclohexylurea, the byproduct of this reaction.

Accepted Answer

The answer of Provide the structure of dicylcohexylcarbodiimide, a common...

Question 3

Consider the following image.   This represents the tertiary structure of a protein.

Accepted Answer

A) True 
 B)False  False

Question 4

Provide the major organic product of the following reaction that is used in the chemical synthesis of peptides.

Accepted Answer

The answer of Provide the major organic product of the...

Question 5

To what structural feature does the term "secondary structure" refer?

Accepted Answer

A) the sequence of amino acids in proteins 
B) the overall folding pattern of proteins 
C) the aggregation of polypeptides 
D) the conformation of local regions of polypeptides 
A) the sequence of amino acids in proteins 
B) the overall folding pattern of proteins 
C) the aggregation of polypeptides 
D) the conformation of local regions of polypeptides

Question 6

Consider the following image.   This represents the quaternary structure of a protein.

Accepted Answer

A) True 
 B)False

Question 7

What is the approximate value of the pKa of the $\alpha$-NH3+ of amino acids?

Accepted Answer

A) 2 
B) 5 
C) 9 
D) 12 
A) 2 
B) 5 
C) 9 
D) 12

Question 8

Disulfide bonds form between the thiol side chains of cysteine. What is the best term to describe the reaction of two thiols to give a disulfide bond?

Accepted Answer

The answer of Disulfide bonds form between the thiol side...

Question 9

The structure of the phenylhydantoin derived from the _____ cycle of the Edman degradation of Phe-Ala-Ser is

Accepted Answer

The answer of The structure of the phenylhydantoin derived from...

Question 10

Which of the following reagents can be used to cleave a benzyloxycarbonyl protecting group from a peptide?

Accepted Answer

A) HBr, CH3CO2H 
B) conc. NaOH 
C) heat 
D) NaCl, H2O 
A) HBr, CH3CO2H 
B) conc. NaOH 
C) heat 
D) NaCl, H2O

Question 11

What are the R/S designations of the two stereocenters of L-threonine?

Accepted Answer

A) 2R,3R 
B) 2R,3S 
C) 2S,3R 
D) 2S,3S 
A) 2R,3R 
B) 2R,3S 
C) 2S,3R 
D) 2S,3S

Question 12

What fragments are produced when porcine dynorphin, a peptide that contains 17 amino acid residues (shown below), is cleaved with chymotropsin?

Accepted Answer

The answer of What fragments are produced when porcine dynorphin,...

Question 13

A tetrapeptide contains the amino acids Phe, Ala, Gly, and Leu. Partial hydrolysis produces the dipeptides Phe-Ala, Ala-Gly, and Leu-Phe. The structure of the tetrapeptide is _________________________. Use the three-letter designations for the amino acids separated by dashes (-).

Accepted Answer

The answer of A tetrapeptide contains the amino acids Phe,...

Question 14

Which of the following amino acids has a sulfhydryl group?

Accepted Answer

A) serine 
B) cysteine 
C) lysine 
D) tyrosine 
A) serine 
B) cysteine 
C) lysine 
D) tyrosine

Question 15

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes.
-_____ is a polypeptide which gives four fragments on treatment with chymotrypsin.

Accepted Answer

A)   
B)   
C)   
D)   
E)  
F) 
G)BOC group
H) 
I) 
J) 
K) 
L) 
M)Z group 
A)   
B)   
C)   
D)   
E)  
F) 
G)BOC group
H) 
I) 
J) 
K) 
L) 
M)Z group

Question 16

The following structure is that of Sanger's reagent.

Accepted Answer

A) True 
 B)False

Question 17

For leucine the pI is the average of pKa1 and pKa2.

Accepted Answer

A) True 
 B)False

Question 18

Which of the following amino acids migrates to the negative electrode on paper electrophoresis at a pH of 7.0?

Accepted Answer

A) lysine 
B) aspartic acid 
C) asparagine 
D) glutamic acid 
A) lysine 
B) aspartic acid 
C) asparagine 
D) glutamic acid

Question 19

Provide the structure of Ser-Phe-Asp.

Accepted Answer

The answer of Provide the structure of Ser-Phe-Asp....

Question 20

Which of the following amino acids has an aromatic side chain?

Accepted Answer

A) tyrosine 
B) glutamine 
C) aspargine 
D) valine 
A) tyrosine 
B) glutamine 
C) aspargine 
D) valine

Exam 27: Amino Acids and Proteins

In Cys-Ile-Ser-Asp-Gly-His-Gly-Gly, the three-letter abbreviation for the N-terminal amino acid is ________.

Provide the structure of dicylcohexylcarbodiimide, a common reagent that is used to couple two amino acid residues by formation of a peptide bond, and the structure N,N'-dicyclohexylurea, the byproduct of this reaction.

Consider the following image. This represents the tertiary structure of a protein.

Provide the major organic product of the following reaction that is used in the chemical synthesis of peptides.

To what structural feature does the term "secondary structure" refer?

Consider the following image. This represents the quaternary structure of a protein.

What is the approximate value of the pKa of the α\alphaα -NH3+ of amino acids?

Disulfide bonds form between the thiol side chains of cysteine. What is the best term to describe the reaction of two thiols to give a disulfide bond?

The structure of the phenylhydantoin derived from the _____ cycle of the Edman degradation of Phe-Ala-Ser is

Which of the following reagents can be used to cleave a benzyloxycarbonyl protecting group from a peptide?

What are the R/S designations of the two stereocenters of L-threonine?

What fragments are produced when porcine dynorphin, a peptide that contains 17 amino acid residues (shown below), is cleaved with chymotropsin?

A tetrapeptide contains the amino acids Phe, Ala, Gly, and Leu. Partial hydrolysis produces the dipeptides Phe-Ala, Ala-Gly, and Leu-Phe. The structure of the tetrapeptide is _________________________. Use the three-letter designations for the amino acids separated by dashes (-).

Which of the following amino acids has a sulfhydryl group?

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is a polypeptide which gives four fragments on treatment with chymotrypsin.

The following structure is that of Sanger's reagent.

For leucine the pI is the average of pKa1 and pKa2.

Which of the following amino acids migrates to the negative electrode on paper electrophoresis at a pH of 7.0?

Provide the structure of Ser-Phe-Asp.

Which of the following amino acids has an aromatic side chain?

Covalent Bonding and Shapes of Molecules

Alkanes and Cycloalkanes

Stereoisomerism and Chirality

Acids and Bases

Alkenes: Bonding, Nomenclature, and Properties

Reactions of Alkenes

Alkynes

Haloalkanes, Halogenation, and Radical Reactions

Nucleophilic Substitution and Beta-Elimination

Alcohols

Ethers, Epoxides, and Sulfides

Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Mass Spectrometry

An Introduction to Organometallic Compounds

Aldehydes and Ketones

Carboxylic Acids

Functional Derivatives of Carboxylic Acids

Enolate Anions and Enamines

Dienes, Conjugated Systems, and Pericyclic Reactions

Benzene and the Concept of Aromaticity

Reactions of Benzene and Its Derivatives

Amines

Catalytic Carbon-Carbon Bond Formation

Carbohydrates

Lipids

Nucleic Acids

Organic Polymer Chemistry

Filters

What is the approximate value of the pK_a of the $\alpha$ -NH₃⁺ of amino acids?

For leucine the pI is the average of pK_a1 and pK_a2.