Table 3. Torsion Angles of Local Minima of the Neutral Leu-EnK Optimized at the M06-2X/6-31+G(d) Level of Theory from the Structures Obtained by the ECEPP Force Field and DFT Methods in the Gas Phase^a.

		Tyr1		Gly2		Gly3		Phe4			Leu5
conf.		ψ1	χ11	ϕ2	ψ2	ϕ3	ψ3	ϕ4	ψ4	χ41	ϕ5	ψ5	χ51
ECEPP3-1	present work	–38	165	113	0	88	–76	–83	–58	–179	–122	157	–179
ECEPP3-2	present work	–38	164	116	7	86	–84	–83	–41	–61	–144	148	–180
ECEPP3-3	present work	–36	161	112	5	83	–75	–90	–47	174	–120	–16	–176
ECEPP3-4	present work	133	–171	–84	63	70	–110	–62	–40	177	–171	–61	172
ECEPP3-5	present work	–25	173	58	–124	–109	1	–176	147	40	–57	150	–180
ECEPP3-6	present work	146	–171	–81	54	75	–97	–96	–13	64	–117	148	–179
ECEPP3-7	present work	–38	164	115	10	86	–88	–87	–32	65	–146	141	178
ECEPP3-8	present work	–21	–165	51	–137	–107	33	–169	137	23	–56	144	–178
ECEPP3-9	present work	122	180	–91	34	87	–48	–117	–6	66	–167	145	180
MM1b	ref (43)	132	176	–119	29	77	–95	–85	–10	62	–119	143	176
MM2b	ref (43)	–25	173	58	–124	–109	1	–176	147	40	–57	150	–180
MM3b	ref (43)	–140	–167	–87	64	86	7	–164	169	64	–151	–33	–175
MM4b	ref (43)	–169	58	–75	94	107	–15	–163	–174	–151	–138	162	–66
VGc	ref (50)	–31	–65	169	148	57	–137	–97	16	55	–123	15	–60
J1d	ref (59)	92	–59	63	14	103	–19	–84	84	–64	–81	58	–53
J2d	ref (59)	85	–64	63	13	103	–16	–72	102	–69	–145	162	–70
J3d	ref (59)	–26	–66	63	24	103	–23	–88	76	–65	–80	58	–51
WH1e	ref (62)	–39	170	74	2	109	–31	–165	127	–178	–161	156	–174
WH2e	ref (62)	–29	–178	57	–133	–108	35	–55	144	177	–150	156	–177
WH3e	ref (62)	137	170	–151	153	158	149	–163	169	–162	–54	148	179

^aTorsion angles (°) are defined in Figure 1.

^bOptimized from the ECEPP2 structures of Meirovitch and Meirovitch.

^cOptimized from the ECEPP3 structures of Vengadesan and Gautham using the MOLS technique.

^dOptimized from the structures of Jalkanen obtained at the B3LYP/6-31G(d) level of theory.

^eOptimized from the structures of Watson and Hirst obtained at the EDF1/6-31+G(d) level of theory.