Question 1

Provide the structure of the tripeptide val-gly-ser at biological pH.

Accepted Answer

The answer of Provide the structure of the tripeptide val-gly-ser...

Question 2

Complete hydrolysis of a hexapeptide gives 2 Gly, Leu, Phe, Pro, and Tyr. Reaction of the peptide with phenylisothiocyanate gave the phenylthiohydantoin of Pro. Partial hydrolysis of the peptide gave the following fragments: Phe-Gly-Tyr, Gly-Phe-Gly, Pro-Leu-Gly, Leu-Gly-Phe. What is the structure of the peptide?

Accepted Answer

Pro-Leu-Gl

Question 3

Give the product for the following reaction.

Accepted Answer

A) alanine 
B) leucine 
C) valine 
D) isoleucine 
E) glycine 
A) alanine 
B) leucine 
C) valine 
D) isoleucine 
E) glycine

Question 4

What is the pI of arginine? The structure and pKa values are shown below.

Accepted Answer

A) 10.76 
B) 7)90 
C) 5)61 
D) 7)33 
E) 9)67 
A) 10.76 
B) 7)90 
C) 5)61 
D) 7)33 
E) 9)67

Question 5

Provide the major organic product(s)of the reaction below.

Accepted Answer

The answer of Provide the major organic product(s)of the reaction...

Question 6

Provide the structure of the tripeptide glu-ser-ala at pH 2.

Accepted Answer

The answer of Provide the structure of the tripeptide glu-ser-ala...

Question 7

Draw a line where cleavage occurs with elastase.

Accepted Answer

The answer of Draw a line where cleavage occurs with...

Question 8

In conventional peptide synthesis, the nitrogen of a given amino acid must be deactivated or blocked while the carboxyl group is activated. Which of the following reagents is used to protect the amino group of an amino acid?

Accepted Answer

A) di-tert-butyl dicarbonate 
B) dicyclohexylcarbodiimide 
C) ninhydrin 
D) trifluoroacetic acid 
E) phenylisothiocyanate 
A) di-tert-butyl dicarbonate 
B) dicyclohexylcarbodiimide 
C) ninhydrin 
D) trifluoroacetic acid 
E) phenylisothiocyanate

Question 9

Draw the predominant form of proline at pH=12.

Accepted Answer

The answer of Draw the predominant form of proline at...

Question 10

Describe how electrophoresis works.

Accepted Answer

A sample of an amino acid mixture is pla

Question 11

Which of the following is an acceptable name for the peptide sequence shown below? Glu-Glu-His-Val-Cys

Accepted Answer

A) 1,2-diglutamylhistidylvalylcysteine 
B) glutamylglutamylhistidylvalylcysteine 
C) 1-glutamyl-2-glutamylhistidylvalylcysteine 
D) diglutamylhistidylvalylcysteine 
E) biglutamylhistidylvalylcysteine 
A) 1,2-diglutamylhistidylvalylcysteine 
B) glutamylglutamylhistidylvalylcysteine 
C) 1-glutamyl-2-glutamylhistidylvalylcysteine 
D) diglutamylhistidylvalylcysteine 
E) biglutamylhistidylvalylcysteine

Question 12

In peptide synthesis, give the use of dicyclohexylcarbodiimide.

Accepted Answer

A) activates the carboxyl group of an amino acid 
B) protects the carboxyl group of an amino acid 
C) protects the amino group of an amino acid 
D) activates the amino group of an amino acid 
E) removes the protecting group on the N-terminal amino acid 
A) activates the carboxyl group of an amino acid 
B) protects the carboxyl group of an amino acid 
C) protects the amino group of an amino acid 
D) activates the amino group of an amino acid 
E) removes the protecting group on the N-terminal amino acid

Question 13

You are given a mixture that contains glutamic acid (pI = 3.2), arginine (pI = 10.8), and valine (pI = 6.0), and you subject the mixture to electrophoresis.
a) Which amino acids migrate toward the cathode when the electrophoresis is carried out at a pH of 7.1?
b) Which amino acids migrate toward the anode when the electrophoresis is carried out at a pH of 7.1?
c) Which amino acid migrates farthest toward the anode at a pH of 7.1?
d) Since amino acids themselves are colorless, how is the separation of amino acids after electrophoresis detected?

Accepted Answer

a) arginine.
b) valine and glu

Question 14

Which of the following is the first step in the determination of the primary structure of proteins?

Accepted Answer

A) determining the number and kind of amino acids in the peptide 
B) reducing the disulfide bridges in the protein 
C) protecting the N-terminal of the peptide 
D) protecting the C-terminal of the peptide 
E) hydrolyzing the protein with dilute acid 
A) determining the number and kind of amino acids in the peptide 
B) reducing the disulfide bridges in the protein 
C) protecting the N-terminal of the peptide 
D) protecting the C-terminal of the peptide 
E) hydrolyzing the protein with dilute acid

Question 15

How is the enzyme chymotrypsin used in peptide structure determination?

Accepted Answer

Chymotrypsin cleaves the peptide chain a

Question 16

Give the product for the following reaction.

Accepted Answer

The answer of Give the product for the following reaction....

Question 17

Draw the structure of the tetrapeptide Ser-Leu-Phe-Pro at pH 7.0.

Accepted Answer

The answer of Draw the structure of the tetrapeptide Ser-Leu-Phe-Pro...

Question 18

Name the peptide.

Accepted Answer

A) ser-cys-phe-gly 
B) ser-cys-tyr-gly 
C) ala-val-leu-gln 
D) phe-ala-val-leu 
E) ala-gly-phe-val 
A) ser-cys-phe-gly 
B) ser-cys-tyr-gly 
C) ala-val-leu-gln 
D) phe-ala-val-leu 
E) ala-gly-phe-val

Question 19

Give the product for the following reaction.

Accepted Answer

A) alanine 
B) leucine 
C) valine 
D) isoleucine 
E) glycine 
A) alanine 
B) leucine 
C) valine 
D) isoleucine 
E) glycine

Question 20

Carboxypeptidase is an enzyme used in the determination of the primary structure of a protein. Specifically, which of the following does it identify?

Accepted Answer

A) the number and kind of amino acids in the protein 
B) the disulfide bridges in the protein 
C) C-terminal amino acid of the protein 
D) N-terminal amino acid of the protein 
E) the number of peptide bonds in the protein 
A) the number and kind of amino acids in the protein 
B) the disulfide bridges in the protein 
C) C-terminal amino acid of the protein 
D) N-terminal amino acid of the protein 
E) the number of peptide bonds in the protein

Exam 22: Amino Acids, Peptides, and Proteins

Provide the structure of the tripeptide val-gly-ser at biological pH.

Give the product for the following reaction.

What is the pI of arginine? The structure and pKa values are shown below.

Provide the major organic product(s)of the reaction below.

Provide the structure of the tripeptide glu-ser-ala at pH 2.

Draw a line where cleavage occurs with elastase.

In conventional peptide synthesis, the nitrogen of a given amino acid must be deactivated or blocked while the carboxyl group is activated. Which of the following reagents is used to protect the amino group of an amino acid?

Draw the predominant form of proline at pH=12.

Describe how electrophoresis works.

Which of the following is an acceptable name for the peptide sequence shown below? Glu-Glu-His-Val-Cys

In peptide synthesis, give the use of dicyclohexylcarbodiimide.

Which of the following is the first step in the determination of the primary structure of proteins?

How is the enzyme chymotrypsin used in peptide structure determination?

Give the product for the following reaction.

Draw the structure of the tetrapeptide Ser-Leu-Phe-Pro at pH 7.0.

Name the peptide.

Give the product for the following reaction.

Carboxypeptidase is an enzyme used in the determination of the primary structure of a protein. Specifically, which of the following does it identify?

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

Electron Delocalization, Resonance, and Aromaticity More About Molecular Orbital Theory

Substitution Reactions of Alkyl Halides

Elimination Reactions of Alkyl Halides Competition Between Substitution and Elimination

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

Organometallic Compounds

Reactions of Alkanes, Radicals

Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Alpha Carbon of Carbonyl Compounds

Reactions of Benzene and Substituted Benzenes

More About Amines Heterocylic Compounds

Carbohydrates

Catalysis

The Organic Mechanisms of the Coenzymes

The Chemistry of Metabolism

Nucleosides, Nucleotides, and Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

Filters