Chain A ( I7 F14 H56 G59 H60 P62 F63 C79 Q83 N87 L90 N91 V152 I153 C154 V155 V156 V157 A158 I159 Y160 N165 T166 W168 S169 S172 G216 R217 T219 S220 V221 I223 Y224 L225 S226 T227 M235 M236 A237 F238 Y239 M240 G241 C242 A244 G245 I248 N249 )