LECTURE 5 PROTEIN STRUCTURE

Question 1

alpha-helix properties

number of residues/turn

pitch

Answer 1

right handed helix

no. of residues is 3.6

pitch (distance helix rises along its axis/turn) is 5.4 Angstroms

Question 2

bond length of C-N single bond

Answer 2

1.49 A

Question 3

bond length of C=N double bond

Answer 3

1.27 A

Question 4

peptide bond

Answer 4

1.32 A

Question 5

a-helices vary from…

Answer 5

4 to >40 residues
- average length in globular properties is 10 residues

Question 6

b-sheet properties

Answer 6

made from at least two (linked) polypeptide chains

strands can be parallel, antiparallel and mixed

they have rippled or pleated appearance

Question 7

distance between adjacent amino acid residues in beta sheet

Answer 7

3.5 A

Question 8

What does h-bonding do to b-sheet

Answer 8

stabilises

Question 9

B-strands are typically between …. and …. residues long

Answer 9

3 and 10

Question 10

Hydrogen bonding occurs between …. of one strand to …. of adjacent strand.

Answer 10

C=O of one strand to N-H

Question 11

B-strands are usually depicted by…..

Answer 11

broad arrows pointing in the direction of the C-terminal end.

Question 12

An all beta-sheet protein

Answer 12

Concanavalin A (ConA) is a lectin (carbohydrate-binding protein).

The tertiary structure comprises 14 ß-strands.

Question 13

common structural folds

Answer 13

globin fold

a/b barrel

B-barrel