Compute the structural analysis of the Protein.

1. What order will the following proteins elute from a caution exchange column loaded at pH 6?
Protein A 10 kDa pI = 8.0
Protein B 15 kDa pI = 4.0
Protein C 25 kDa pI = 6.5
a. A, then B, then C
b. B, then C, then A
c. A, then C, then B
d. B, then A, then C

2. If the same proteins shown in problem 12 were run on gel filtration chromatography and SDS-PAGE, which of the following statements would be true?
a. Protein A would elute first using gel filtration chromatography and run fastest on SDS-PAGE.
b. Protein B would elute first using gel filtration chromatography and run fastest on SDS-PAGE.
c. Protein C would elute first using gel filtration chromatography and run fastest on SDS-PAGE.
d. Protein A would elute first using gel filtration chromatography while C would run fastest on SDS-PAGE.
e. Protein C would elute first using gel filtration chromatography while A would run fastest on SDS-PAGE.

3. Place the following steps for a round of Edman's degradation (sequencing) in order:
I. cleave the N-terminal amino acid
II. Label the N-terminal amino acid
III. Use HPLC to detect the N-terminal amino acid
a. First I, then II, then III, then repeat.
b. First II, then I, then III, then repeat.
c. First III, then II, then I, then repeat.
d. First I, then III, then II, then repeat.
e. First III, then I, then II, then repeat.

4. The formation of a peptide bond between two amino acids is an ex of a (n)______________ reaction.
a. cleavage
b. condensation
c. group transfer
d. isomerization
e. oxidation reduction

5. The average molecular weight of the 20 standard amino acids is 138, but biochemists use 110 when estimating the number of amino acids in a protein of known molecular weight. Why?
1. The number 110 is based on the fact that the average molecular weight of a protein is 110,000 with an average of 1,000 amino acids.
2. The number 110 reflects the higher proportion of small amino acids in proteins, as well as the loss of water when the peptide bond forms.
3. The number 110 reflects the number of amino acids found in the typical small protein, and only small proteins have their molecular weight estimated this way.
4. The number 110 takes into account the relatively small size of nonstandard amino acids.
5. The number 138 represents the molecular weight of conjugated amino acids.

6. Which of the following is correct with respect to the amino acid composition of proteins?
a. Larger proteins have a more uniform distribution of amino acids than smaller proteins.
b. Proteins contain at least one each of the 20 different standard amino acids.
c. Proteins with different functions usually differ significantly in their amino acid composition.
d. Proteins with the same molecular weight have the same amino acid composition.

7. The average molecular weight of an amino acid in a protein increases with the size of the protein. Which of the following refers to particularly stable arrangements of amino acid residues in a protein that give rise to recurring patterns?
a. Primary structure.
b. Secondary structure.
c. Tertiary structure.
d. Quaternary structure.
e. None of the above.

8. Which of the following describes the overall three-dimensional folding of a polypeptide?
a. Primary structure.
b. Secondary structure.
c. Tertiary structure.
d. Quaternary structure.
e. None of the above.

9. Which type of interaction stabilizes secondary structure?
1. van der Waals
2. hydrogen bonding
3. ionic (electrostatic)
4. covalent
5. all of the above

10. Which of the following best represents the backbone arrangement of two peptide bonds?
a. Cα-N-Cα-C-Cα-N-Cα-C
b. C α-C-N-Cα-C-N
c. C-N-Cα-Cα-C-N
d. Cα-N-C-C-N-Cα
e. Cα-Cα-C-N-Cα-Cα-C