Exam 15: Biomolecules: Amino Acids, Peptides, and Proteins

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Draw the structure of the predominant form of leucine at pH = 10.00.

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Question 21

Refer to the data below to answer the following questions: The octapeptide saralasin is a specific antagonist of angiotensin II. A derivative of saralasin is used therapeutically as an antihypertensive. Amino acid analysis of saralasin show the presence of the following amino acids: Ala, Arg, His, Pro, Sar, Tyr, Val₂ Refer to instructions. Sar is the mnemonic for sarcosine, N-methyl aminoethanoic acid. Draw the structure of sarcosine.

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Question 22

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Draw a Fischer projection of L-leucine and label the chirality center(s) as R or S.

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Question 23

Show the steps involved in a synthesis of F-G-I using the Merrifield procedure.

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Question 24

Which of the following amino acids has a non-polar side chain?

(Multiple Choice)

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Question 25

Instructions: Match a structure from the list below to each of the following terms.

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Question 26

Which of the following tripeptides is not hydrolysed by chymotrypsin?

(Multiple Choice)

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Question 27

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

(Multiple Choice)

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Question 28

Instructions: Match a structure from the list below to each of the following terms.

A peptide containing eight amino acid residues with a C-terminal valine.

An amino acid in its zwitterionic form.

Source from which many coenzymes are derived.

Val-Phe-Leu-Met-Tyr-Pro-Gly-Trp-Cys-Glu

Correct Answer:

Verified

A peptide containing eight amino acid residues with a C-terminal valine.

An amino acid in its zwitterionic form.

Source from which many coenzymes are derived.

A polypeptide which gives four fragments on treatment with chymotrypsin.

A peptide coupling reagent.

The product of an Edman degradation.

An amino acid with a protected carboxyl group.

(Matching)

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Question 29

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. How many possible stereoisomers of leucine are there?

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Question 30

Instructions: Consider the following structure. Based on this structure answer the following question(s). Refer to instructions. Circle the peptide bonds.

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Question 31

BOC protecting groups are generally removed by treatment with trifluoroacetic acid. On the structures provided below, draw arrows consistent with electron flow in the mechanism of this reaction.

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Question 32

Instructions: Consider the following structure. Based on this structure answer the following question(s). Refer to instructions. Name the peptide using both the three-letter and one-letter codes.

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Question 33

Write the equation for the reaction, using methanol (CH₃OH), that would render the carboxyl group of alanine unreactive.

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Question 34

Which of the following reagents can be used to cleave a tert-butoxycarbonyl (Boc) protecting group from a peptide?

(Multiple Choice)

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Question 35

Which of the following amino acids has a sulfur-containing side chain?

(Multiple Choice)

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Question 36

During peptide synthesis, the carboxylic acid group may be protected as the methyl ester. Aqueous base hydrolysis is utilized to remove the ester protecting group. Write the complete stepwise mechanism for the hydrolysis of the methyl ester of BOC-Val-Gly-OCH₃, above. Show all intermediate structures and all electron flow with arrows.

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Question 37

Define isoelectric point.

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Question 38

Which of the following tripeptides is not hydrolysed by trypsin?

(Multiple Choice)

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Question 39

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Leucine is described as an essential amino acid. What does this mean?

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Question 40

Showing 21 - 40 of 43

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Draw the structure of the predominant form of leucine at pH = 10.00.

Show the steps involved in a synthesis of F-G-I using the Merrifield procedure.

Which of the following amino acids has a non-polar side chain?

Instructions: Match a structure from the list below to each of the following terms.

Which of the following tripeptides is not hydrolysed by chymotrypsin?

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

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. How many possible stereoisomers of leucine are there?

Instructions: Consider the following structure. Based on this structure answer the following question(s). Refer to instructions. Circle the peptide bonds.

BOC protecting groups are generally removed by treatment with trifluoroacetic acid. On the structures provided below, draw arrows consistent with electron flow in the mechanism of this reaction.

Instructions: Consider the following structure. Based on this structure answer the following question(s). Refer to instructions. Name the peptide using both the three-letter and one-letter codes.

Write the equation for the reaction, using methanol (CH₃OH), that would render the carboxyl group of alanine unreactive.

Which of the following reagents can be used to cleave a tert-butoxycarbonyl (Boc) protecting group from a peptide?

Which of the following amino acids has a sulfur-containing side chain?

Define isoelectric point.

Which of the following tripeptides is not hydrolysed by trypsin?

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Leucine is described as an essential amino acid. What does this mean?

Structure and Bonding:acids and Bases

Alkanes: The Nature of Organic Compounds

Alkenes and Alkynes: the Nature of Organic Reactions

Reactions of Alkenes and Alkynes

Aromatic Compounds

Sterechemistry at Tetrahedral Centers

Organohalides: Nucleophilic Substitutions and Eliminations

Alcohols, Phenols, Ethers, and Their Sulfur Analogs

Aldehydes and Ketones: Nucleophilic Addition Reactions

Carboxylic Acids and Derivatives: Nucleophilic Acyl Substitution Reactions

Carbonyl Alpha-Substitution Reactions and Condensation Reactions

Amines

Structure Determination

Biomolecules: Carbohydrates

Biomolecules: Lipids and Nucleic Acids

The Organic Chemistry of Metabolic Pathways

Filters

Exam 15: Biomolecules: Amino Acids, Peptides, and Proteins

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pKa1 = 2.36 and pKa2 = 9.60. Refer to instructions. Draw the structure of the predominant form of leucine at pH = 10.00.

Show the steps involved in a synthesis of F-G-I using the Merrifield procedure.

Which of the following amino acids has a non-polar side chain?

Instructions: Match a structure from the list below to each of the following terms.

Which of the following tripeptides is not hydrolysed by chymotrypsin?

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

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pKa1 = 2.36 and pKa2 = 9.60. Refer to instructions. How many possible stereoisomers of leucine are there?

Instructions: Consider the following structure. Based on this structure answer the following question(s). Refer to instructions. Circle the peptide bonds.

BOC protecting groups are generally removed by treatment with trifluoroacetic acid. On the structures provided below, draw arrows consistent with electron flow in the mechanism of this reaction.

Instructions: Consider the following structure. Based on this structure answer the following question(s). Refer to instructions. Name the peptide using both the three-letter and one-letter codes.

Write the equation for the reaction, using methanol (CH3OH), that would render the carboxyl group of alanine unreactive.

Which of the following reagents can be used to cleave a tert-butoxycarbonyl (Boc) protecting group from a peptide?

Which of the following amino acids has a sulfur-containing side chain?

Define isoelectric point.

Which of the following tripeptides is not hydrolysed by trypsin?

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pKa1 = 2.36 and pKa2 = 9.60. Refer to instructions. Leucine is described as an essential amino acid. What does this mean?

Structure and Bonding:acids and Bases

Alkanes: The Nature of Organic Compounds

Alkenes and Alkynes: the Nature of Organic Reactions

Reactions of Alkenes and Alkynes

Aromatic Compounds

Sterechemistry at Tetrahedral Centers

Organohalides: Nucleophilic Substitutions and Eliminations

Alcohols, Phenols, Ethers, and Their Sulfur Analogs

Aldehydes and Ketones: Nucleophilic Addition Reactions

Carboxylic Acids and Derivatives: Nucleophilic Acyl Substitution Reactions

Carbonyl Alpha-Substitution Reactions and Condensation Reactions

Amines

Structure Determination

Biomolecules: Carbohydrates

Biomolecules: Lipids and Nucleic Acids

The Organic Chemistry of Metabolic Pathways

Filters

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Draw the structure of the predominant form of leucine at pH = 10.00.

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. How many possible stereoisomers of leucine are there?

Write the equation for the reaction, using methanol (CH₃OH), that would render the carboxyl group of alanine unreactive.

Instructions: Refer to the data below to answer the following question(s). Leucine is an essential amino acid with the systematic name 2-amino-3-methylpentanoic acid. It has pK_a1 = 2.36 and pK_a2 = 9.60. Refer to instructions. Leucine is described as an essential amino acid. What does this mean?