Chain A ( E35 D36 P37 V38 V39 A40 V42 T44 D45 A46 T47 L48 R49 C50 W67 L69 T70 D71 Q74 V76 L107 R108 L109 V112 R113 V114 T115 D116 E117 G118 S119 Y120 T121 )