Chain A ( F11 A14 E15 V18 V19 L22 C23 R31 W32 Q33 K34 I35 F36 K37 S38 L40 V41 E42 L43 L44 V45 S46 Y47 G48 F51 F52 L55 L116 R117 R118 L119 V120 T121 L122 I123 S124 )