L8 - Protein Structure and Function II

Question 1

Tertiary Structure

Answer 1

The association of Secondary structure into compact domains

Question 2

Disulphide bridges

Answer 2

2 Cysteines cross link forming 1 Cystine

Question 3

Quaternary Structure

Answer 3

Subunits associate into a multimeric complex involving multiple polypeptide chains

Question 4

Homodimers

Answer 4

2 copies of the same protein associated together as a mirror image

Question 5

Heterodimers

Answer 5

2 different polypeptide chains associated together

Question 6

Antibodies

Answer 6

Four polypeptide chains with intramolecular and intermolecular disulphide bridges

Question 7

Globular proteins

Answer 7

Protein chains arranged in compact domains
Usually active components of cell machinery

Question 8

Fibrous proteins

Answer 8

Protein chains arranged in fibres
Have a structural role

Question 9

Keratin properties

Answer 9

Mechanically durable
Coiled Coil
Staggered antiparallel tetramer -> Protofilaments, Protofibrils, Microfibrils

Question 10

Keratin sequence

Answer 10

7 Amino Acids in an alpha helix
A and D are hydrophobic, the rest can be any amino acid

Question 11

Fibroin Properties

Answer 11

Strong as stretching breaks covalent bonds
Flexible as Van der Waal’s between sheets

Question 12

Fibroin sequence

Answer 12

Gly-Ser-Gly-Ala-Gly-Ala
Glycine project one way, Serine and Alanine the other way

Question 13

Collagen Properties

Answer 13

Most abundant vertebrate protein
Forms strong fibres
Triple helix of loose helices

Question 14

Collagen sequence

Answer 14

1/3 Gly, 15-30% Pro and Hyp
Cannot form alpha helices due to Pro and Hyp