Question 1

Provide the structure of the tripeptide val-gly-ser at pH 12.

Accepted Answer

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Question 2

Provide the structure of the tripeptide glu-ser-ala at pH 12.

Accepted Answer

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Question 3

Give a detailed,stepwise mechanism for the formation of the activated acyl derivative from the reaction of an amino acid with N,N'-dicyclohexylcarbodiimide.

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Question 4

Provide the structure of Thr-Gln-Met at pH 7.0.

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Question 5

Draw the dipeptide Val-Tyr at pH 7.0.

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Question 6

In peptide synthesis,give the use of di-tert-butyl dicarbonate.

Accepted Answer

Di-tert-butyl dicarbonate is used to protect the amino group of an amino acid during peptide synthesis, preventing it from reacting prematurely.

Question 7

Explain the importance of the Merrifield method in peptide synthesis.

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Question 8

In peptide synthesis,give the use of trifluoroacetic acid.

Accepted Answer

Trifluoroacetic acid is commonly used in peptide synthesis to remove the protecting group on the N-terminal amino acid. This allows the peptide to be cleaved from the resin and purified. It does not activate or protect the carboxyl or amino groups of the amino acids.

Question 9

Provide the structure of the tripeptide val-gly-ser at pH 2.

Accepted Answer

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Question 10

Which of the following structures can polypeptides have?

Accepted Answer

Polypeptides can have primary, secondary, tertiary, and quaternary structures. The primary structure refers to the specific sequence of amino acids in the polypeptide chain, while secondary structure refers to the local folding patterns such as alpha-helices and beta-sheets. Tertiary structure is the overall three-dimensional shape of the protein, and quaternary structure refers to the arrangement of multiple polypeptide chains in a protein complex. Therefore, all of the above choices are correct.

Question 11

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

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Question 12

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

Di-tert-butyl dicarbonate (Boc) is commonly used to protect the amino group of an amino acid in conventional peptide synthesis. It is able to selectively react with the amino group, forming a stable Boc-amino acid derivative that can be deprotected later in the synthesis. Other reagents listed may be used in other steps of peptide synthesis, but not for protecting the amino group.

Question 13

Which type of protein,globular or fibrous,tends to function primarily as structural parts of an organism?

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Question 14

Give the product for the following reaction.

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Question 15

Provide the structure of Ala-Ser-Gly at biological pH.

Accepted Answer

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Question 16

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

Accepted Answer

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Question 17

In peptide synthesis,give the use of dicyclohexylcarbodiimide.

Accepted Answer

Dicyclohexylcarbodiimide (DCC) is used in peptide synthesis to activate the carboxyl group of an amino acid by forming an intermediate O-acylisourea. This reactive intermediate then reacts with the nucleophilic amino group of another amino acid to form a peptide bond.

Question 18

When a disulfide linkage is formed,the compound containing this new linkage has been

Accepted Answer

A disulfide linkage is formed by the oxidation of two thiol (-SH) groups to form a covalent bond between two sulfur atoms. Therefore, the compound containing the disulfide linkage has been oxidized.

Question 19

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

Accepted Answer

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Question 20

Explain the chemistry behind giving a "permanent" to a head of hair.

Accepted Answer

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Quiz 21: Amino Acids,peptides,and Proteins

Provide the structure of the tripeptide val-gly-ser at pH 12.

Provide the structure of the tripeptide glu-ser-ala at pH 12.

Give a detailed,stepwise mechanism for the formation of the activated acyl derivative from the reaction of an amino acid with N,N'-dicyclohexylcarbodiimide.

Provide the structure of Thr-Gln-Met at pH 7.0.

Draw the dipeptide Val-Tyr at pH 7.0.

In peptide synthesis,give the use of di-tert-butyl dicarbonate.

Explain the importance of the Merrifield method in peptide synthesis.

In peptide synthesis,give the use of trifluoroacetic acid.

Provide the structure of the tripeptide val-gly-ser at pH 2.

Which of the following structures can polypeptides have?

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

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?

Which type of protein,globular or fibrous,tends to function primarily as structural parts of an organism?

Give the product for the following reaction.

Provide the structure of Ala-Ser-Gly at biological pH.

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

In peptide synthesis,give the use of dicyclohexylcarbodiimide.

When a disulfide linkage is formed,the compound containing this new linkage has been

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

Explain the chemistry behind giving a "permanent" to a head of hair.