|
Number
|
5
|
6
|
9
|
10
|
11
|
13
|
14
|
15
|
17
|
24
|
25
|
27
|
28
|
31
|
32
|
35
|
36
|
|
Aminoacid residue of wild type
|
F
|
N
|
Q
|
Q
|
N
|
F
|
Y
|
E
|
L
|
E
|
E
|
R
|
N
|
I
|
Q
|
K
|
D
|
|
Distance (Å)
|
5.7
|
11
|
6.4
|
4.2
|
6.5
|
3.8
|
3.4
|
7.9
|
4.0
|
8.4
|
8.7
|
8.6
|
6.9
|
5.8
|
8.1
|
4.5
|
9.8
|
|
fSASA (%)
|
78
|
94
|
36
|
47
|
64
|
40
|
63
|
50
|
46
|
78
|
96
|
23
|
71
|
17
|
60
|
64
|
68
|
|
Mixed codon used in the library
|
YWT
|
MAY
|
CAW
|
CAW
|
MAY
|
YWT
|
YAT
|
SAW
|
CWK
|
SAW
|
SAW
|
CRY
|
MAY
|
MWT
|
CAW
|
MAW
|
SAT
|
|
Substituted amino acids in the library
|
H
| | | | |
H
| |
H
|
H
|
H
|
H
| | |
H
| |
H
| |
|
Y
|
H
|
H
|
H
|
H
|
Y
|
H
|
D
|
Q
|
D
|
D
|
H
|
H
|
N
|
H
|
N
|
H
|
|
L
| | | | |
L
| |
Q
| |
Q
|
Q
| | |
L
| |
Q
| |
- Distance in the table indicates the length between the PAB residue and the nearest positively charged residue in IgG-Fc. fSASA indicates the extent of solvent exposure of the side chain in wild-type amino acid residues of PAB. The seventeen mutation positions finally selected were classified into two groups: (1) the PAB residues were located within 9 Å from the positively charged IgG-Fc residues and (2) the PAB residues were located between 9 and 11 Å from the IgG-Fc residues, and with a fractional solvent-accessible surface area (fSASA) ((fSASA) = (SASA) (native)/SASA (denatured)) value of more than 68%. The following abbreviations are used for mixed bases: R = (A or G), Y = (C or T), M = (A or C), K = (G or T), S = (G or C) and W = (A or T). Substituted amino acid residues in the library indicate non-wild-type residues encoded by a mixed codon.
