lec 9

Question 1

which bonds in a protein can rotate

Answer 1

dihedral bonds (phi=c-n psi=c-c)
peptide bonds have only two confirmations which is either cis or trans

Question 2

which two atoms have a prptide bond between them

Answer 2

deprotonated N and carbonyl carbon

Question 3

isoelectric point

Answer 3

the ph where amino acid has no net charge: zwitterion

Question 4

charged amino acids

Answer 4

his, arg, lys, asp, glu

Question 5

hydrophobic amino acids

Answer 5

glycine, alanine, valine, leucine, isoleucine, methionine, proline

Question 6

hydrophylic amino acids

Answer 6

serine, threonine, cysteine, asparagine, glutamine

Question 7

charged amino acids

Answer 7

arginine, lysine, histidine, glutamic acid, aspartic acid

Question 8

how many amino acids per turn in alpha-helix

Answer 8

3.6 amino acids, 5.4A/turn (1.5 A every residue)

Question 9

how are r groups arranged on alpha helix and how can they be amipathic.

Answer 9

-r groups on outside of helix (never on the inside)
-if theres a side chain thats hydrophobic every 3-4 amino acids (cuz theres 3.6 amino acids every turn) all the hydrophobics will end up one side together making that side hydrophobci and other phylic

!not the same as beta-barrel–Bbarrel is amipathic in the way that its hydrophylic on the inside and phobic on the outside cuz its a rolled up sheet!

Question 10

3 most common aminos in α
helices, β strands, and β turns, respectively?

Answer 10

gaunine, alanine, leucine (all np and small)

valine, isoleucne, tyrosine

proline, asparagine, glycine (P helps w sharp turns, N h bonds, G small)