Question 1

Provide a reasonable synthesis of racemic alanine from ethanol.

Accepted Answer

1. PCC
2.

Question 2

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 3

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) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 4

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 5

Provide the structure of L-arginine at pH 2.0.

Accepted Answer

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

Question 6

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 7

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

Accepted Answer

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

Question 8

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

Question 9

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

Question 10

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

Question 11

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

Question 12

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

Question 13

Peptide bonds are:

Accepted Answer

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

Question 14

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

Accepted Answer

2,4-dinitrofluoroben

Question 15

Show where chymotrypsin would cleave the peptide shown below.

Accepted Answer

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

Question 16

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. 
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 17

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 
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

Question 18

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. 
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 19

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 20

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...

Exam 24: Amino Acids, Peptides, and Proteins

Provide a reasonable synthesis of racemic alanine from ethanol.

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

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)

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

Provide the structure of L-arginine at pH 2.0.

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

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

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

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

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

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

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

Peptide bonds are:

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

Show where chymotrypsin would cleave the peptide shown below.

Nearly all naturally occurring amino acids:

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

The isoelectric point is important in:

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

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

Introduction and Review

Structure and Properties of Organic Molecules

Structure and Stereochemistry of Alkanes

The Study of Chemical Reactions

Stereochemistry

Alkyl Halides: Nucleophilic Substitution and Elimination

Structure and Synthesis of Alkenes

Reactions of Alkenes

Alkynes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Infrared Spectroscopy and Mass Spectrometry

Nuclear Magnetic Resonance Spectroscopy

Ethers, Epoxides, and Thioethers

Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Lipids

Synthetic Polymers

Filters

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)