topic 4

Question 1

what is important in the formation of a helicies? what ar the other physical protierties?

Answer 1

HB between the C=O and the NH group, 4 AA residues away. (i, i+4)
phi= -60-> -180
psi= -60
3.6 AA per turn and each turn is 1.5A (rise)
side chains will extend outwards (for right have helix)

Question 2

how many AA are there in each turn of and a helix? what is the rise of each turn?

Answer 2

AA=3.6
rise=1.5A

Question 3

what is an anti-parralel beta sheet?

Answer 3

when 2 B strands are oriented in opposite directions

Question 4

what is a mixed beta sheet?

Answer 4

when more than 2 B strands are orientated in opposite directions

Question 5

what is a parralel beta sheet

Answer 5

and all strnads are orientated in the same direction

Question 6

what is the crucial stabilizing factor for the formation of secondary proteins?

Answer 6

the HB that form between the C=O group and the NH group

Question 7

how are side chains organized in beta sheets?

Answer 7

in alternating order-> down, up, down, up…

Question 8

what are the favourable combinations of phi and psi for a beat sheet?

Answer 8

phi=-60->-130
psi=80-180