quarternary structure: subunit association

Question 1

why is increasing size via quaternary interactions more efficient than increasing chain length

Answer 1

if something is wrong in a protein subunit, it is more efficient to remake a subunit rather than the entire protein.
- uses less atp. WHenever you add an amino acid you are using about 4 amino acids, which is going to be less atp for a subunit rather than a huge protein

Question 2

protomer

Answer 2

identical subunits or groups of subunits
ex: 2 alpha, 2 beta OR (a,B)2

Question 3

oligomers

Answer 3

made of protomers
protein made of protomeric subunits

Question 4

homotypic vs heterotypic subunits

Answer 4

homotypic: same (ex: 2 alpha subunits)
heterotypic: different (ex Alpha and beta)

Question 5

Contact regions between subunits resemble what and why?

Answer 5

interior of protein, because you want the oligomers to associate together.
Why to not use polar instead of van der waals and hydrophobic effect?
water is going to hydrogen bond and prevent association

Question 6

Why is only rotational symmetry possible instead of reflection?

Answer 6

Reflection is not possible between two L amino acids, would need to be D and L to be reflective and D are not found in the body.

Question 7

Dyad axis

Answer 7

2 protomeric units aligned antiparallel to each other.
Means if you have a contact region with A and B trying to contact each other, its a good spot for an active site because it means you can get your active site amino acids from both protomeric units and then repeat it for the other active site on the other side of the protein.