Table 2.

Hydrogen bonds

Type	Donor	Acceptor**	Donor– acceptor, Å	Hydrogen*– acceptor, Å	CO⋅⋅⋅N angle, degrees
Intermol	N1	O11†	3.035	2.17	143
Solvent	N2	W1	2.887	2.00
Head-to-tail	N3	O9†	2.870	2.01	147
Head-to-tail	N4	O7†	2.979	2.14	169
Helix 4 → 1	N5	O2	2.975	2.41	123
Transition
Helix 5 → 1	N6	O2	2.956	2.10	166
Helix 5 → 1	N7	O3	3.139	2.35	162
Helix 4 → 1	N8	O5	3.046	2.18	116
Helix reversal	N9	O4	2.818	2.02	150
β-	N10	O17	3.001	2.16	158
Intermol	N11	O1‡	2.825	1.98	147
β-	N12	O15	2.914	2.05	128
	N13 (dPro)
Intermol	N14	O6§	2.889	2.002	158
β-	N15	O12	2.982	2.18	133
	N16	No hydrogen bond
β-	N17	O10	2.858	1.99	154
Solvent	W1	W2¶	2.564
Solvent	W2	Oo∥	2.681
Solvent	W2	O5	2.773

*Hydrogen atoms were placed in idealized positions with N–H = 0.90 Å. 

^†At symmetry equivalent −x, ½ + y, −z. 

^‡At symmetry equivalent −x, −½ + y, −z. 

^§At symmetry equivalent −1 + x, y, −1 + z. 

^¶At symmetry equivalent 1 − x, ½ + y, −z. 

^∥At symmetry equivalent 1 − x, −½ + y, −z. 

**O8, O13, O14, and O16 do not participate in hydrogen bonding.