Table 5.

Spectrum of mutations in α-helices^a

Amino acid	Original residues	Expected residues	χ2	P value	Mutant residues	Expected residues	χ2	P value
A	89	83	0.45	5.03E-01	23	57	20.13***	7.25E-06
C	26	14	11.27***	7.88E-04	56	33	15.76***	7.18E-05
D	34	44	2.23	1.35E-01	59	38	11.78***	5.99E-04
E	61	96	12.71***	3.64E-04	26	33	1.54	2.15E-01
F	28	36	1.76	1.84E-01	37	38	0.02	8.87E-01
G	48	30	10.69***	1.08E-03	46	54	1.31	2.52E-01
H	23	21	0.13	7.19E-01	41	38	0.26	6.12E-01
I	41	51	1.96	1.61E-01	29	50	8.63**	3.30E-03
K	20	61	27.70***	1.41E-07	52	33	10.73***	1.05E-03
L	101	112	1.04	3.09E-01	49	78	10.86***	9.85E-04
M	41	29	5.11*	2.37E-02	24	21	0.34	5.59E-01
N	22	27	1.08	3.00E-01	29	38	2.08	1.49E-01
P	29	24	1.15	2.84E-01	90	57	19.38***	1.07E-05
Q	28	45	6.12*	1.34E-02	55	33	14.41***	1.47E-04
R	153	64	122.78***	1.56E-28	73	80	0.70	4.04E-01
S	36	46	2.22	1.36E-01	53	88	13.66***	2.19E-04
T	30	38	1.84	1.75E-01	61	57	0.31	5.79E-01
V	62	59	0.18	6.69E-01	69	57	2.61	1.06E-01
W	24	16	4.19*	4.06E-02	32	17	14.36***	1.51E-04
Y	32	33	0.01	9.29E-01	24	28	0.68	4.08E-01
Sum	928	928			928	928

^aχ²-numbers in italics indicate underrepresentation and numbers in bold overrepresentation compared to random distribution based on amino acid frequencies. The results of the χ² are shown with significance level: * P < 0.05; ** P < 0.01; *** P < 0.001.