# Eech specified mutation is performed as a single mutant. total 30 1 R 8 Q 1 E 10 K 1 E 16 K 1 R 25 K 1 L 28 M 1 D 36 S 1 V 37 A 1 R 41 Q 1 A 42 Q 1 Q 59 T 1 R 62 E 1 D 66 K 1 K 75 R 1 A 77 V 1 L 79 V 1 D 98 Q 1 C 102 S 1 Q 105 N 1 N 106 Q 1 C 108 F 1 S 110 I 1 E 112 D 1 E 113 S 1 Q 120 L 1 Q 122 R 1 E 126 K 1 A 134 L 1 I 141 V 1 R 146 T 1 Q 153 K