. 2003 Oct;85(4):2119–2146. doi: 10.1016/s0006-3495(03)74640-2

TABLE 1.

Dihedral angle bounds, lower and upper, for α-helix and β-strand residues

Conformer	φ^L	φ^U	ψ^L	ψ^U
α	−90	−40	−60	−10
β	−180	−80	80	180
unassigned	−180	180	−180	180