Homework 2

Homework 2 (Due: Sept. 28, 2005)

Proteins: Globular, Membrane, Fibrous

1. List the three main classes of proteins and two distinguishing features of each.

2. Identify the most significant force in determining the 3⁰ structure of globular proteins and list two secondary ways in which these proteins maintain their most active conformation.

3. Give two examples of globular proteins and identify one feature that they all share.

4. Describe the main features of an enzyme and distinguish between coenzymes and prosthetic groups.

5. Describe a common structural modification of circulating globular proteins and indicate which specific residues are modified.

6. Compare glycosylation of circulating proteins that occurs in a specific, enzyme-directed fashion with the glycosylation that can occur in a spontaneous and uncontrolled ("non- enzymatic") fashion. How does "non-enzymatic" glycosylation provide useful clinical information concerning diabetic patients?

7. Identify which domain of a membrane protein is usually glycosylated and how membrane glycoproteins may contain a vast amount of biological "information".

8. List three functional categories of membrane proteins.

Proteins-Structural

1. Describe the secondary and tertiary structure of mature collagen and explain the importance of the many glycine residues.

2. List five different modifications of amino acid residues in collagen. Identify the cofactors required for these modification reactions.

3. Delineate the steps in collagen maturation.

4. Identify the feature unique to elastin plus two features it shares with collagen.

5. List other types of fibrous structural proteins and identify the predominant 2⁰ structural pattern in each.

6. Describe an important stabilizing modification of a-keratin and a simple intervention to disrupt and then reform this type of modification.

Membranes I and II

1. Identify the common features of membranes.

2. Describe the major features of the fluid-mosaic model of membranes.

3. Compare the effects of saturated and unsaturated lipids and cholesterol on membrane fluidity.

4. Explain the biochemical basis for individuals having different blood types (A, B, O).

5. Compare the characteristics of peripheral and integral membrane proteins.

6. List the three classes of integral membrane proteins, discuss the characteristics and give an example of each.

7. Diagram (describe) the action of G-Proteins.

8. Define active and passive transport.

9. Discuss (diagram) the role of Na⁺ / K⁺ ATPase.

Myoglobin / Hemoglobin

1. Diagram the basic structural features of myoglobin (Mb) and list the important differences between myoglobin and hemoglobin (Hb).

2. Diagram the iron-heme complex (detailed structure of heme not necessary) and describe how it binds oxygen with the aid of residues in the Mb or Hb protein chain.

3. Discuss the binding of carbon monoxide to the iron-heme complex.

4. Draw a simple oxygen affinity curve for myoglobin, which exists as a monomer.