Chain A ( M10 S81 T83 I84 T85 P86 T88 A89 W94 F96 P105 A108 G109 V158 Q162 C175 E177 W244 F246 S247 F250 N251 R254 D255 Q267 Y268 F269 F270 G271 I272 A273 T274 H275 )