Table 1.

Backbone dihedral angles (in degrees), pseudorotational parameters (A and P; in degrees), relative energy (ΔE^gp; in kcal/mol) and relative energy with respect to the lowest energy conformation of the most stable dipeptide (ΔE^#gp#; in kcal/mol) of the minimum energy conformations characterized for Ac-βtAmp-NHMe, Ac-βcAmp-NHMe, Ac-γtAmp-NHMe and Ac-γcAmp-NHMe at the B3LYP/6-31+G(d,p) level in the gas phase.

# Conf.	ω0	φ	ψ	ω	(A, P)	ΔEgp	ΔE#gp#
Ac-βtAmp-NHMe
t-γL[d]	-174.0	-83.1	71.9	-177.6	(38.4, -117.2)a	0.0b	1.4
c-εL[u]	1.2	-66.7	178.8	175.9	(38.2, 92.2)c	2.8	4.2
c-αL[u]	6.8	-69.6	-35.1	179.4	(37.8, 82.2)d	5.9	7.3
c-εL[d]	-0.6	-77.5	145.8	176.0	(37.5, 75.8)e	5.9	7.3
Ac-βcAmp-NHMe
t-γL[d]	-174.1	-83.6	78.6	-175.5	(39.8,118.8)f	0.0g	0.5
t-αL[d]	-170.5	-88.7	-7.5	173.9	(39.2, -112.5)h	4.0	4.5
c-αL[d]	10.4	-84.3	-17.4	-177.2	(36.2, 104.0)i	4.3	4.8
c-εL[d]	-3.0	-74.5	172.9	177.8	(39.3, -126)j	5.0	5.5
c-αL[u]	8.2	-96.2	-0.7	178.6	(42.8, -122.2)k	5.6	6.1
t-αL[u]	-170.8	-70.5	-19.3	175.2	(40.2, 78.1)l	8.6	9.1
Ac-γtAmp-NHMe
t-γL[u]	-170.8	-83.7	75.2	-176.6	(37.3, 102.6)m	0.0n	1.3
c-αL[d]	10.5	-91.6	-3.9	-179.9	(37.8, -112.5)o	2.8	4.1
c-εL[u]	-0.8	-62.5	147.7	175.7	(39.3, 93.1)p	5.9	7.2
Ac-γcAmp-NHMe
t-γL[d]	-172.8	-82.9	76.6	-176.0	(32.73,-116.5)q	0.0r	0.0
t-γL[u]	-174.5	-81.8	77.4	-176.2	(37.8, 109.3)s	1.5	1.5
c-αL[d]	8.5	-68.5	-47.6	-176.4	(34.1, -93.2)t	2.7	2.7
c-αL[u]	8.0	-79.0	-18.9	-177.6	(37.2, 89.4)u	5.2	5.2
t-αL[u]	-170.9	-79.3	-9.2	175.5	(37.9, 93)v	5.7	5.7
c-εL[d]	3.8	-70.8	148.6	174.6	(35.4, -104.1)w	6.0	6.0
c-εL[u]	0.9	-62.5	148.2	176.9	(39, 89.3)x	7.9	7.9

^aχ⁰= -17.5°, χ¹= 33.5°, χ²= -38.0°, χ³= 27.4° and χ⁴= -6.0°.

^bE= -628.667446 a.u.

^cχ⁰= -1.4°, χ¹= -21.6°, χ²= 35.7°, χ³= -36.2° and χ⁴= 23.9°.

^dχ⁰= 5.1°, χ¹= -26.01°, χ²= 37.3°, χ³= -33.9° and χ⁴= 18.1°.

^eχ⁰= -10.3°, χ¹= -13.4°, χ²= 31.0°, χ³= -36.6° and χ⁴= 29.8°.

^fχ⁰= -18.7°, χ¹= 34.5°, χ²= -38.3°, χ³= 27.0° and χ⁴= -5.0°.

^gE= -628.668896 a.u.

^hχ⁰= -15.0°, χ¹= 32.9°, χ²= -39.2°, χ³= 30.2° and χ⁴= -9.2°.

ⁱχ⁰= -8.8°, χ¹= 27.5°, χ²= -36.3°, χ³= 30.7° and χ⁴= -13.7°.

^jχ⁰= -23.1°, χ¹= 36.5°, χ²= -37.4°, χ³= 23.8° and χ⁴= -0.1°.

^kχ⁰= -22.8°, χ¹= 39.0°, χ²= -41.6°, χ³= 28.0° and χ⁴= -3.0°.

^lχ⁰= 8.3°, χ¹= -29.5°, χ²= 39.9°, χ³= -35.0° and χ⁴= 16.7°.

^mχ⁰= -8.2°, χ¹= -15.5°, χ²= 31.9°, χ³= -36.3° and χ⁴= 28.4°.

ⁿE= -628.667515 a.u.

^oχ⁰= -14.4°, χ¹= 31.0°, χ²= -37.7°, χ³= 28.7° and χ⁴= -9.1°.

^pχ⁰= -2.1°, χ¹= -21.9°, χ²= 36.6°, χ³= -37.1° and χ⁴= 25.1°.

^qχ⁰=-14.6°, χ¹= 28.9°, χ²= -32.4°, χ³= 23.1° and χ⁴= -5.6°.

^rE= -628.669674 a.u.

^sχ⁰= -12.5°, χ¹= -11.8°, χ²= 29.9°, χ³= -36.8° and χ⁴= 31.3°.

^tχ⁰= -1.9°, χ¹= 21.8°, χ²= -33.0°, χ³= 31.1° and χ⁴= -18.7°.

^uχ⁰= 0.4°, χ¹= -22.5°, χ²= 35.4°, χ³= -34.6° and χ⁴= 21.9°.

^vχ⁰= -2.0°, χ¹= -21.2°, χ²= 35.2°, χ³= -35.9° and χ⁴= 24.1°.

^wχ⁰= -8.6°, χ¹= 27.4°, χ²= -35.3°, χ³= 29.6° and χ⁴= -13.4°.

^xχ⁰= 0.5°, χ¹= -23.7°, χ²= 37.2°, χ³= -36.3° and χ⁴= 22.8°.