BCMB 8190
PROBLEM SET 6 - ANSWERS
1)
2) a) Sorry, labels for lower peaks should have been masked out – answers are on the problem set.
b) Upfield peaks are weaker because the two bond Ni to Ci-1 coupling constant is smaller than the
one bond coupling to Ci
c) Weaker peaks will not always be upfield – it is coincidence in this case. They just occur at the
carbon chemical shifts of the respective alpha carbons.
3)
a) T1/T2 = 2/3 x (τm ωN)2 = 750/62 = 2/3 x (τm x 2π x 60 x 106)2 => τm = 11.3 ns
b) 1/T2 = (dd/4) x 2/5 x S2 x τm = 1.46 x 109 x 2/5 x S2 x 1.13 x 10-8 => S = 0.39
c) (3cos2θ -1)/2 = S = 0.8 => 21º