Table 2.

Summary of reference results on ppII. The red As represent the studied residues.

Reference	System	Methodology	(ϕ, ψ) of ppII	ppII population	other population
Tamburro3, 74		PDB	(−75°, 145°)
Hamm17–19	A $\mathrm{A}$A	2D IR	(−60°, 140°)	80%	α = 20%
Schweitzer-Stenner11–12	A $\mathrm{A}$A	Polarized Raman, FTIR, VCD and ECD	(−60°, 150°)	50%	β = 50%
Schweitzer-Stenner16	A $\mathrm{A}$A	Polarized Raman, FTIR, and VCD	(−70° ± 20°, 150° ± 20°)	84%	β = 16%
	A $\mathrm{A}$A		(−69° ± 10°, 140° ± 10°)	84%	β = 8%, α = 4%, γ = 5%
Schweitzer-Stenner14	A $\mathrm{A}$KA	Polarized Raman, FTIR, VCD, ECD and NMR	(−65°, 150°)	63%	β = 7%, α = 30%
	A $\mathrm{A}$AA		(−65°, 150°)	66%	β = 14%, α = 20%
	AA $\mathrm{A}$A		(−70°, 140°)	73%	β = 17%, α = 10%
Cho31	Averaged A $\mathrm{AA}$	NMR, used 3J(HN,Hα) from Ref20	AMBER ff03	65%	β = 35%
			Gromos 43A1	88%	β = 12%
Graf20	A $\mathrm{AAA}$A	NMR	Gromos 43A1	84%	β = 16%
This work	A $\mathrm{AAA}$A	Fitting	(−60°, 150°)
		C36 prediction	(−61°, 145°)	59%	β = 22%, α = 12%
		Simulation based on C36 ensemble	(−61°, 145°)	~100%