Download Problem set 4 - Amino acids/Proteins

Problem set 4
Amino acids & Proteins
1. The isoelectric point (pI) for the threonine is 5.87. Draw its structure in these solutions:
a) pH = 6
b) pH = 2
c) pH = 10
2. Draw the Fischer projection structure for D-cysteine and L-tyrosine.
3. Draw the structure of Met-Ser-Cys and Thr-Leu-Phe. Identify the N-terminal and Cterminal. Circle all of the R groups. Put a box around the peptide bonds.
4. Use the tripeptides of problem 3 and show the hydrolysis reaction for them.
5. Draw the different ionic structures of tripeptide Met-Ser-Cys at pH 2.0, 7.0, and 10.0.
Dr. Behrang Madani
Chemistry 203
CSUB
6. Identify the primary, secondary, and tertiary structure in the numbered boxes:
4
3
1
7
2
6
5
9
8
7. Classify the following amino acids as nonpolar, polar but neutral, acidic, or basic:
a)
b)
c)
d)
e)
f)
Arginine
Glutamic acid
Tyrosine
Leucine
Asparagine
Phenylalanine
8. Where do we find a salt bridge in a protein? How can an acid, a base, an alcohol, or heat
cause the denaturation in a protein?
Dr. Behrang Madani
Chemistry 203
CSUB
9. What is the role of an enzyme in our body? Which part of an enzyme does it participate in
the biochemical reactions? How the enzyme can change the rate of the reaction?
10. What is the role of the cofactors in our body? They are divided into how many groups?
Explain them.
11. What are the three differences between water-soluble vitamins and fat-soluble vitamins?
12. What are the three differences between the competitive inhibitors and the noncompetitive
inhibitors?
Dr. Behrang Madani
Chemistry 203
CSUB