Hemoglobin-1

Question 1

Give 2 examples of secondary protein structure

Answer 1

Alpha helix and Beta-sheet

Question 2

Describe the alpha-helix structure of secondary protein structure

Answer 2

Helix is stabilized by hydrogen bonding

• Hydrogen bonds occur between the atoms that participate in the peptide bond
• So “repetitive hydrogen” bonding
• Every 4th peptide bond interacts with each other
• amino acid side chains stick out to the side of the helix

Question 3

Describe the B-sheet of secondary protein structure

Answer 3

Stabilized by hydrogen bonding
-Involves the atoms that participate in the peptide bond

   - Repetitive hydrogen bonding

Amino acid side chains stick out above and below the plane of the sheet

Question 4

Describe a quarter nary structure if a protein

Answer 4

Two or more polypeptides that associate together to carry out some function

Question 5

Describe a tertiary structure of a protein

Answer 5

Regions of secondary structures fold on themselves to form a tertiary structure

Question 6

Give an example of a fibrous protein and why it is as such

Answer 6

Collagen is a fibrous protein

A tightly wound triple hekix(not alpha helix)

Collagen has a repetitive structure :

 - every 3 amino acid is glycine 
 - Helps with tight packing

Question 7

What are the characteristics of globular proteins?

Answer 7

• Polar amino acid side chains on surface(adds to solubility)
• Nonpolar amino acid side chains in the interior hydrophobic core)
• some sort of metabolic function: catalytic, transport etc.
• Variety/combo os secondary structure type: B-sheet, a-helix, turn

Question 8

Most globular proteins are a combination of ….

Answer 8

Alpha helix and beta-sheet linked by turns (or beta bends)

Question 9

What is a prosthetic group?

Answer 9

A non-protein component found on some proteins

For hemoglobin, heme is the prosthetic group

Question 10

Differentiate the common oxidation states of iron

Answer 10

Ferrous state- 2+ Fe

Ferric state- 3+

Question 11

How does ferrous iron play a role in holding oxygen in hemoglobin?

Answer 11

Fe2+ can form 6 bonds 4 covalent coordinate bonds to nitrogens

Histidine in hemoglobin binds to the iron

The last binding site on iron forms a reversible bond to oxygen