Table 1.

One letter amino acid codes used in the text.

One letter code	Amino acid	Conservative replacements
A	alanine	A, E, S, T
C	cysteine/cystine	S, T, V
D	aspartic acid	E
E	glutamic acid	A, D
F	phenylalanine	M, W, Y
G	glycine	N, P
H	histidine	K, R
I	isoleucine	L, V
K	Lysine	H, R
L	leucine	I, V
M	methionine	F, W, Y
N	asparagine	G, D, Q
P	proline	G
Q	glutamine	N, E
R	arginine	H, K
S	serine	A, T
T	threonine	A, I, S
V	valine	A, I, L
W	tryptophan	F, M, Y
Y	tyrosine	F. M, W