Lecture 2: Fibrous Proteins

Question 1

What can you say about Ceratine-like structures?

Answer 1

• Hair, feathers, nails, hooves
• Little or NO tertiary structures
• Long alpha helical - in mammals, reptiles

=> Build up together
-> helices -> coiled coils -> shifted tetramers -> protofilament -> microfibrils (great amount of interactions)

Question 2

What can you say about Collagen?

Answer 2

• Extracellular protein found in connective tissue
• Strange sequance of Gly-X-Y with X often Proline, Y often Hydroproline
  -> run into great length of amino acids

Picture shows Polyproline structure
- don’t form secondary structures -> but form extended left-handed helix

Question 3

What makes the collagen so strong?

Answer 3

• Intensive hydrogen bonding among the strings BUT ALSO orchestrated network of water also holds the helix together

Question 4

What are often discussed structures composed of intensive binding of hydrogen to beta sheets (with the additional water network)? NEGATIVE

Answer 4

Amyloid fibrils
- Important in some diseases: Altheimer’s, spongiform encephalopathies, type 2 diabetes => progressive disorders with high mortality rate
- Resistant to protein degradation
- Often misfolded -> plagues

Question 5

What are often discussed structures composed of intensive binding of hydrogen to beta sheets (with the additional water network)? POSITIVE

Answer 5

Fibroin = protein that makes up spider nets, is what we extract from silk worms -> strong and ligher
- Sequence of Ser-Gly-Ala-Gly-Ala-Gly