Secondary Structures Flashcards
1
Q
what is an alpha helix
A
peptide backbone twists
each AA bonds to an AA n+4 away
~3.6 AA/turn
2
Q
common themes in alpha helices
A
proline impossible (rigidity)
glycine rare (flexibility)
~20 NP in a row is transmembrane
(-) charge 3-4 AA away from (-) is rare
3
Q
helical wheel
A
helps determine amphipathic alpha helix
4
Q
beta sheets can be
A
antiparallel
parallel
5
Q
common themes of beta sheets
A
alternating NP/P groups = amphipathic
proline not possible in middle (rigidity)
6
Q
if antiparallel beta sheet #atoms involved
A
alternating 10/14
7
Q
if parallel beta sheet #atoms involved
A
12
8
Q
disulfide bonds
A
form between two cysteines (covalently) NP
