Secondary structure - dimensions of trans peptide bond - how to know if partial double
a) 1.3 Å, 1.5 Å, resonance observed
b) 1.5 Å, 2.0 Å, no resonance observed
c) 1.5 Å, 1.3 Å, resonance observed
d) 2.0 Å, 1.5 Å, no resonance observed