Dissection of Factors Affecting the Variability of the Peptide Bond Geometry and Planarity

Table 2

Average values of bond angles with standard deviations and occurrences (in bracket) of non-Gly/non-Pro residues in α-helix or coil in the 3°  × 3° box centered at = (−63°, −43°). The differences (coil minus α-helix) between the average values of the distributions and the statistical significance of these differences ( value) are reported.

Bond angle			Difference	value
	α-Helix; (11480)	Coil; (181)
NC^αC	110.9 ± 1.2	111.6 ± 1.6	0.7
C^αCO	120.6 ± 0.9	120.4 ± 0.9	−0.2	0.0051
C^αCN^+1	116.9 ± 0.9	116.7 ± 1.1	−0.2	0.019
OCN^+1	122.5 ± 0.9	122.8 ± 0.9	0.3
C^−1NC^α	120.6 ± 1.1	120.7 ± 1.2	0.1	0.87
NC^αC^β	110.6 ± 1.1	110.6 ± 1.1	0.0	0.81
C^βC^αC	110.6 ± 1.3	110.2 ± 1.4	−0.4