Question 1

Nearly all naturally occurring amino acids:

Accepted Answer

A)   are racemic mixtures.
B)   are achiral.
C)   have the (R)  configuration at the α-carbon.
D)   have the (S)  configuration at the α-carbon.
E)   have basic side chains.

Question 2

Peptide bonds are:

Accepted Answer

A)   ester linkages.
B)   imido linkages.
C)   ether linkages.
D)   amide linkages.
E)   disulfide linkages.

Question 3

Draw the form of L-tryptophan which is present at biological pH.

Accepted Answer

The answer of Draw the form of L-tryptophan which is...

Question 4

What compound is also known as Sanger reagent, and how is it used in peptide structure determination?

Accepted Answer

2,4-dinitrofluoroben...

Question 5

Provide the structure of the predominant form of L-phenylalanine present in an aqueous solution at biological pH.

Accepted Answer

The answer of Provide the structure of the predominant form...

Question 6

A protein bonded to a sugar residue would be classified as a:

Accepted Answer

A)   simple protein.
B)   glycoprotein.
C)   lipoprotein.
D)   metalloprotein.
E)   nucleoprotein.

Question 7

The isoelectric point is important in:

Accepted Answer

A)   the enzymatic resolution of amino acids.
B)   electrophoresis.
C)   determination of the C-terminal amino acid.
D)   determination of the N-terminal amino acid.
E)   the ninhydrin test.

Question 8

Given the following pKa values, what is the major ionization state of histidine at pH 11? (α-COOH = 2.0, α-NH3+ = 9.0 and R-group imine = 6.5)

Accepted Answer

A)  3+ = 9.0 and R-group imine = 6.5)  
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Question 9

Which of the following amino acids has its isoelectric point at the lowest pH?

Accepted Answer

A)   arginine
B)   aspartic acid
C)   valine
D)   glycine
E)   methionine

Question 10

Which of the following reagents is used to protect the amino group of the N-terminal residue in solution-phase peptide synthesis?

Accepted Answer

A)   lithium diisopropyl amide
B)   benzyl chloroformate
C)   phenyl isothiocyanate
D)   dicyclohexylcarbodiimide
E)   trifluoroacetic acid

Question 11

Which of the following amino acids has its isoelectric point at the highest pH?

Accepted Answer

A)   glycine
B)   aspartic acid
C)   valine
D)   lysine
E)   methionine

Question 12

Provide a structure of the dipeptide Ala-Ser at biological pH.

Accepted Answer

The answer of Provide a structure of the dipeptide Ala-Ser...

Question 13

Show where chymotrypsin would cleave the peptide shown below.

Accepted Answer

The answer of Show where chymotrypsin would cleave the peptide...

Question 14

Which of the following amino acids has its isoelectric point at the highest pH?

Accepted Answer

A)   glycine
B)   aspartic acid
C)   valine
D)   arginine
E)   methionine

Question 15

Provide a reasonable synthesis of racemic alanine from ethanol.

Accepted Answer

1. PCC
2. ...

Question 16

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

Accepted Answer

The answer of Which type of protein, globular or fibrous,...

Question 17

Provide the structure of L-arginine at pH 2.0.

Accepted Answer

The answer of Provide the structure of L-arginine at pH...

Question 18

Show the step-wise synthesis of glutamic acid starting with α-ketoglutarate and ammonia.

Accepted Answer

The answer of Show the step-wise synthesis of glutamic acid...

Question 19

The nonprotein part of a conjugated protein is called a ________ group.

Accepted Answer

The answer of The nonprotein part of a conjugated protein...

Question 20

What is the practical limit on the use of carboxypeptidase in providing sequence information?

Accepted Answer

A)   two residues on the C-terminal end
B)   two residues on the N-terminal end
C)   three residues on the N-terminal end
D)   three residues on the C-terminal end
E)   six residues on the N-terminal end

Exam 24: Amino Acids, Peptides, and Proteins

Provide the structure of the predominant form of L-phenylalanine present in an aqueous solution at biological pH.

Correct AnswerverifiedShow Answer

Provide a structure of the dipeptide Ala-Ser at biological pH.

Correct AnswerverifiedShow Answer

Which of the following amino acids has its isoelectric point at the lowest pH?

Correct AnswerverifiedShow Answer

Nearly all naturally occurring amino acids:

Correct AnswerverifiedShow Answer

Show the step-wise synthesis of glutamic acid starting with α-ketoglutarate and ammonia.

Correct AnswerverifiedShow Answer

Provide a reasonable synthesis of racemic alanine from ethanol.

Correct Answerverified1. PCC2. ...View AnswerShow Answer

Show where chymotrypsin would cleave the peptide shown below.

Correct AnswerverifiedShow Answer

Peptide bonds are:

Correct AnswerverifiedShow Answer

Draw the form of L-tryptophan which is present at biological pH.

Correct AnswerverifiedShow Answer

Which of the following amino acids has its isoelectric point at the highest pH?

Correct AnswerverifiedShow Answer

Provide the structure of L-arginine at pH 2.0.

Correct AnswerverifiedShow Answer

What compound is also known as Sanger reagent, and how is it used in peptide structure determination?

Correct Answerverified2,4-dinitrofluoroben...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

A protein bonded to a sugar residue would be classified as a:

Correct AnswerverifiedShow Answer

What is the practical limit on the use of carboxypeptidase in providing sequence information?

Correct AnswerverifiedShow Answer

The nonprotein part of a conjugated protein is called a ________ group.

Correct AnswerverifiedShow Answer

Which of the following reagents is used to protect the amino group of the N-terminal residue in solution-phase peptide synthesis?

Correct AnswerverifiedShow Answer

Which of the following amino acids has its isoelectric point at the highest pH?

Correct AnswerverifiedShow Answer

The isoelectric point is important in:

Correct AnswerverifiedShow Answer

Given the following pKa values, what is the major ionization state of histidine at pH 11? (α-COOH = 2.0, α-NH3+ = 9.0 and R-group imine = 6.5)

Correct AnswerverifiedShow Answer

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1. PCC
2. ...
View Answer

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2,4-dinitrofluoroben...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Given the following pKa values, what is the major ionization state of histidine at pH 11? (α-COOH = 2.0, α-NH₃⁺ = 9.0 and R-group imine = 6.5)

Correct Answer
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