Chain A ( S19 S20 I21 A22 V92 H93 S94 I95 G96 F97 M98 M103 G104 G119 I120 I122 S123 G146 M147 D148 F149 Y158 M161 A164 K165 P193 I194 R195 T196 L197 A198 M199 I202 L207 I215 )