Electronic properties of amino acid side chains: quantum mechanics calculation of substituent effects

BMC Chemical Biology

Table 2 Electronic properties of amino acid side chains.

	pKa^a	σ_I	H_MΔPH	σ_R	σ_α	σ_F	A_I	HN_NMR^b
P	10.60	0	0.10	0.10	-0.04	0.02^c	0	-
C	10.28	-0.01	-0.01	0.01	-0.03	0.06^c	0.01	8.18
A	9.69	0.05	0.05	0	-0.01	0.05	0.05	8.12
I	9.68	0.06	0.08	0.02	-0.04	0.04	0.06	7.99
E	9.67	0.68	1.25	0.57	-0.04	-1.14	0.68	8.40
V	9.62	0.01	0.09	0.08	-0.03	-0.04	0.01	8.08
L	9.60	0.02	0.07	0.05	-0.04	-0.03	0.02	7.99
D	9.60	0.51	1.80	1.29	-0.03	-1.77	0.51	8.38
G	9.60	0	0	0	0	0	0	8.36
W	9.39	0.06	0.15	0.09	-0.12	-0.24	0.06	8.03
M	9.21	0.08	-0.04	-0.12	-0.05	-0.30	0.08	8.12
H	9.17	-0.01	0.21	0.22	-0.06	-0.58	0.01	8.36
S	9.15	-0.03	-0.05	-0.02	-0.02	-0.38	0.03	8.30
F	9.13	0.04	0.06	0.02	-0.08	-0.45	0.04	7.93
Q	9.13	-0.10	-0.07	0.03	-0.05	-0.35	0.10	8.19
Y	9.11	0.05	0.02	-0.03	-0.09	-0.42	0.05	8.10
T	9.10	-0.05	-0.03	0.02	-0.03	-0.44	0.05	8.17
R	9.04	-0.26	-0.75	-0.49	-0.08	0.27	0.26	8.23
K	8.95	-0.16	-1.11	-0.95	-0.05	0.51	0.16	8.29
N	8.80	-0.14	-0.20	-0.06	-0.04	-0.56	0.24	8.33

^aThe pKa data were taken from Edsall [58]. ^bThe HN_NMR data were derived from the NMR work of Wishart et al. [32] and represent chemical shift values in p.p.m. for the amide proton of residues in the coil conformation. The other terms have been defined in the text. ^cEstimated on the basis of chemically similar groups due to anomalous pKa.